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Development of microscopic simulation model for heterogeneous traffic using object oriented approach
Abstract
Roads in India carry heterogeneous traffic with wide variations in static and dynamic characteristics of vehicles. The traffic flow is also generally devoid of lane discipline, with vehicles occupying any available road space ahead. Modeling of such heterogeneous traffic is generally complex in nature and simulation has been proven to be effective in studying such traffic. This paper presents the development of a model through object oriented programming (OOP) approach for simulating heterogeneous traffic. Several unique traffic characteristics have been considered in the modeling process. C++ language is used for this purpose. OOP leads to better structured codes for simulation and facilitates the development, maintainability and expandability of such codes. The first part of the paper explains the various logics of simulation such as vehicle generation, vehicle placement and vehicle movement. The second part of the paper describes the features of OOP, description of classes and class relationships. The last part of the paper presents the validation and advantages of the developed model.
... As a result, the interactions among vehicles and the resulting maneuvers they undertake are much more complex, which makes it difficult for traffic engineers to model such mixed traffic flow conditions through analytical methods. Hence, simulation technique is considered as an effective tool for modeling such complex system, as well as its stochasticity (Arasan and Koshy 2005;Venkatesan, Gowri, and Sivanandan 2008;Mallikarjuna and Rao 2011;Asaithambi et al. 2012). The study is motivated by the following considerations: Many research works have been carried out to develop mixed traffic simulation models for unidirectional movement of vehicles (Oketch 2000;Arasan and Koshy 2005;Venkatesan, Gowri, and Sivanandan 2008;Mallikarjuna and Rao 2011;Hu, Wang, and Yang 2012;Chen et al. 2013;Mathew, Munigety, and Bajpai 2013;Asaithambi et al. 2018). ...
... Hence, simulation technique is considered as an effective tool for modeling such complex system, as well as its stochasticity (Arasan and Koshy 2005;Venkatesan, Gowri, and Sivanandan 2008;Mallikarjuna and Rao 2011;Asaithambi et al. 2012). The study is motivated by the following considerations: Many research works have been carried out to develop mixed traffic simulation models for unidirectional movement of vehicles (Oketch 2000;Arasan and Koshy 2005;Venkatesan, Gowri, and Sivanandan 2008;Mallikarjuna and Rao 2011;Hu, Wang, and Yang 2012;Chen et al. 2013;Mathew, Munigety, and Bajpai 2013;Asaithambi et al. 2018). Only few attempts have been made to develop bidirectional mixed traffic simulation models (Chakroborty, Agrawal, and Vasishtha 2004;Dey, Chandra, and Gangopadhyay 2008;Luo, Liu, and Guo 2014;Budhkar and Maurya 2014;Kotagi, Asaithambi, and Murthy 2018). ...
... Few microscopic simulation models have been developed to model the vehicular behavior on the mid-block sections of urban divided roads in mixed traffic focusing on unidirectional traffic movement (Oketch 2000;Arasan and Koshy 2005;Gundaliya, Mathew, and Dhingra 2008;Meng et al. 2007;Venkatesan, Gowri, and Sivanandan 2008;Mallikarjuna and Rao 2011;Hu, Wang, and Yang 2012;Chen et al. 2013;Mathew, Munigety, and Bajpai 2013;Metkari, Budhkar, and Maurya 2013;Kanagaraj et al. 2013;Asaithambi et al. 2018). In these studies, longitudinal and lateral movements are modeled separately. ...
Most of the urban cities in developing and emerging countries (e.g. India, China) consist of large proportion of undivided roads which carry mixed traffic with non-lane discipline. Vehicular manoeuvers on such roads are complex and traffic flow in a particular direction is predominant compared to other direction which increases the peak hour congestion. Possible ways to reduce congestion are to improve the operation of existing road systems through better traffic management measures (e.g. reversible lane mechanism) and microscopic simulation model is identified as a widely used tool for this purpose. With this motivation, the overall objective of this research paper is to evaluate reversible lane (tidal flow) operation using a microscopic traffic simulation model developed specifically for urban undivided roads (bi-directional) in mixed traffic. The concept of influence area is introduced in the model to identify the most influencing leader vehicle. The model is applied to evaluate the impact of reversible lane operation on capacity of roads using different vehicular compositions commonly observed on major urban arterials in Indian cities. Results shows that there is an improvement in capacity during peak hours after implementing reversible lanes.
... At time t, a vehicle applying a constant acceleration over the interval will travel a distance during the time interval given by - (16) in which is the velocity at the beginning of the scan interval. The velocity after is given by- (17) In the simulation model the position of vehicles traveling along the approaches and exits are measured according to their distances from the entry point of the approach lane. Thus, if the position of a vehicle at time t is then the updated position at the end of interval , w.r.t its entry point is given by (18) At the entry point, the acceleration of both leader and follower is assigned to be zero. ...
... Lane Changing Model(Venkatesan et al., 2008).Figs. 6 and 7 describe the basic lane changing mechanism of a lane-based model. ...
Traffic congestion is of great concern for the inhabitants of Dhaka city because of elongated travel time, loss of productive hours. Despite of all the planning programs and projects designed by the government, the outrageous congestion problem is worsening day by day because of the rapid growth of population and increase in the number of vehicles. The traffic simulation model provides the option to simulate a real project in the computer and observe its impacts prior to the implementation. However, these available simulation models are not suitable for simulating heterogeneous non-lane based mixed traffic. For these reasons, the author has developed a simulation model using the OOP tool. The author has coded the road network and all of its components and characteristics in Java because of its multithreading, high performing capacity, more natural, logical, secure, architecture-neutral, portable and dynamic characteristics. The simulation model developed by the author is capable of determining fundamental traffic flow characteristics such as flow rate, average speed and density and their relations. The model has been calibrated and validated against the field data. However, the simulation results have been verified with the available traffic flow models and found satisfactory.
... In order to improve the accuracy of capacity estimation, adjustment factors become the focus of research. The common adjustment factors include lane width, vehicle composition, and various shared lanes [20][21][22][23][24][25][26][27][28][29][30][31][32]. Now adjustment factors for lane width are discussed. ...
... Due to the difference in vehicle performance, based on measured data, estimation of passenger car unit (PCU) was analyzed. Further, adjustment factor for heavy vehicles was studied [23][24][25][26]. Radhakrishnan et al. [23] found that HCM has recommended a saturation flow model primarily for homogeneous conditions, with limited ability to solve heterogeneity. ...
An insufficient functional relationship between adjustment factors and saturation flow rate (SFR) in the U.S. Highway Capacity Manual (HCM) method increases an additional prediction bias. The error of SFR predictions can reach 8%–10%. To solve this problem, this paper proposes a comprehensive adjusted method that considers the effects of interactions between factors. Based on the data from 35 through lanes in Beijing and 25 shared through and left-turn lanes in Washington, DC, the interactions between lane width and percentage of heavy vehicles and proportion of left-turning vehicles were analyzed. Two comprehensive adjustment factor models were established and tested. The mean absolute percentage error (MAPE) of model 1 (considering the interaction between lane width and percentage of heavy vehicles) was 4.89% smaller than the MAPE of Chinese National Standard method (Standard Number is GB50647) at 13.64%. The MAPE of model 2 (considering the interaction between lane width and proportion of left-turning vehicles was 33.16% smaller than the MAPE of HCM method at 14.56%. This method could improve the accuracy of SFR prediction, provide support for traffic operation measures, alleviate the traffic congestion, and improve sustainable development of cities.
... Procedural programming languages (C, PASCAL, FORTRAN) put more emphasis on procedure (code), whereas input-output data are considered an auxiliary factor (17). Thus, they do not focus on real-world problems and design needs. ...
... DES can be included in the object-oriented programming (OOP) category that offers a highly sophisticated versatile programming environment for the development of large-scale and complex software systems because of its inherent features of encapsulation, inheritance, and polymorphism (19). The main benefits of OOP are scalability, easy maintenance, enhanced modification, and reusability of the models; in addition, OOP facilitates bridge the gap between the realworld system and the simulation model (17). The modeling approach is particularly suitable for describing the pedestrian crossing process. ...
Road accident reports show that many accidents involve pedestrians, the category of road users generally considered "weak" with respect to other mobility users, and that these accidents occur at pedestrian crossings. Therefore, traffic engineers need simulation tools that can forecast the results of a given design solution and compare the solution with alternatives. A simplified model that simulates interactions between pedestrians and vehicles at road crossings is presented. In the model, the crossing process is represented as a discrete events system, and the model uses basic and easy-to-collect parameters to estimate interactions. Pedestrian behavior in the decision phase is characterized with a gap acceptance criterion, which is based on parameters derived from probabilistic distribution and takes into account the heterogeneity of the pedestrian population. Interaction between pedestrians during the crossing phase is taken into account with a cellular model of the crossing area. The model allows estimation of safety benefits for pedestrians and crossing level of service for both pedestrians and vehicular flows, starting from site geometry and field measurements of flow parameters of pedestrians and vehicles. The model was applied to a real site in a case study. The effects of traffic-calming interventions were also simulated and evaluated.
... To analyze a wide range of roadway and traffic conditions, the use of simulation models is necessary to adequately control for various factors. For this purpose, a microscopic traffic simulation model for mixed-traffic conditions developed by Venkatesan et al. was used (7). The simulation model consists of the following major modules related to traffic flow on a two-lane road: (a) vehicle generation, (b) vehicle placement, and (c) vehicle movement. ...
Mixed traffic in the cities of many developing countries is characterized by a lack of lane discipline, varying compositions of constituent vehicle types, and significant intraclass variability in static and dynamic characteristics. However, the influence of these factors on traffic flow parameters is not well understood. This study addressed the influence of lane discipline, intraclass variability, and composition on traffic flow characteristics under heterogeneous traffic conditions in Chennai, India. A microscopic traffic simulation model was calibrated and validated with field data from a four-lane divided urban arterial road in Chennai. The preliminary analysis indicated that factors such as composition, intraclass variability, and lane discipline had a statistically significant effect on stream speed. Speed flow and speed density relationships were developed on the basis of simulation results. These results showed a clear influence of lack of lane discipline, variability, and composition on stream speed. The influence varied depending on volume level and type of subject vehicle. The effect of composition on capacity was quantified. When two-wheelers had a predominant share, they enjoyed better performance in the absence of lane discipline. However, when cars and heavy vehicles had a significant presence, the impact of the lack of lane discipline was much smaller. The simulation model was applied to evaluate a range of traffic control measures based on vehicle type and lane. The results showed the promise of some measures based on vehicle class, namely, the exclusion of autorickshaws or autorickshaws and heavy vehicles. The findings have interesting implications for efficiency, user experience, and equity in mixed traffic.
... These vehicles significantly vary in the static characteristics (such as length, width, and size) and dynamic characteristics (such as acceleration/deceleration and maximum speed). The acceleration/deceleration characteristics will affect the gap required for safe stopping and thereby the gap a vehicle maintains (Kanagaraj et al. 2008;Asaithambi et al. 2009). Lan and Chang (2004) used General Motors model to explain the motorcycle's following behaviours in two situations: (1) only one leading vehicle in front; (2) two or more leading vehicles in front and neighbouring-front (including either left-front, right-front, or both). ...
Car following models replicate the behaviour of a car following another car. In mixed traffic conditions, leader-follower vehicle types are not only car-car cases but also there are different combinations of vehicles (e.g., car-two wheeler and heavy vehicle-auto-rickshaw). Due to weak lane discipline, the follower is unable to strictly follow the lead vehicle. The other types of following behaviour like staggered following, following between vehicles, etc. are also observed under mixed traffic conditions. Depending on speed and position of vehicles in front, the subject vehicle may follow a leading vehicle with varying levels of lateral separation or stagger. The nature, extent and impact of such interactions need to be investigated for characterizing following behaviour under mixed traffic conditions. Hence, the present study focuses on analysis and modelling of vehicle following behaviour under mixed traffic conditions.
The current study uses an open access mixed traffic trajectory data collected on an urban arterial road in Chennai city, India. The collected dataset includes 3005 vehicle trajectories with a total of 111,629 observations. To identify the different types of following behaviour, the extent of overlap (%) between leader-follower pair was used. The vehicle following behaviour was classified into three types: 1) Car Following 2) Staggered following and 3) Following between two vehicles. The vehicle following behaviour were analysed for different categories of vehicles and also, for different types of follower-leader pair. When the follower is a smaller size vehicle compared to a leader, it generally follows the leader. It was observed that when the vehicle size increases, staggered following behaviour of vehicle also increases. Subject vehicle chooses a following behaviour based on size of follower and leader, speeds of follower and leader, longitudinal gap between follower and leader, types of follower and leader. Multinomial Logistic Regression model was used to model the choices of vehicle following behaviour. This study has interesting implications in identifying vehicle-specific and vehicle following parameters for car following models to be adopted under mixed traffic and non-lane discipline traffic conditions.
... 4. Lateral movement Lateral movement is often modeled in discrete lanes or strips. Several authors (Oketch et al. [42], Arasan and Koshy [9], Kanagaraj et al. [73], Asaithambi et al. [74]) assumed a constant lateral speed (e.g. 1 m/sec). Siddique [44] assumed move discretely between strips (each 0.5 m wide). ...
Most published microscopic driving behavior models, such as car following and lane changing, were developed for homogeneous and lane-based settings. In the emerging and developing world, traffic is characterized by a wide mix of vehicle types (e.g., motorized and non-motorized, two, three and four wheelers) that differ substantially in their dimensions, performance capabilities and driver behavior and by a lack of lane discipline. This paper presents a review of current driving behavior models in the context of mixed traffic, discusses their limitations and the data and modeling challenges that need to be met in order to extend and improve their fidelity. The models discussed include those for longitudinal and lateral movements and gap acceptance. The review points out some of the limitations of current models. A main limitation of current models is that they have not explicitly considered the wider range of situations that drivers in mixed traffic may face compared to drivers in homogeneous lane-based traffic, and the strategies that they may choose in order to tackle these situations. In longitudinal movement, for example, such strategies include not only strict following, but also staggered following, following between two vehicles and squeezing. Furthermore, due to limited availability of trajectory data in mixed traffic, most of the models are not estimated rigorously. The outline of modeling framework for integrated driver behavior was discussed finally.
... The traffic-flow models reported for homogeneous traffic may not be sufficient to character- ize the heterogeneous traffic found on Indian roads. Attempts to- ward modeling such heterogeneous traffic have been mainly microscopic in nature ( Tiwari et al. 2008;Mallikarjuna and Rao 2009;Venkatesan et al. 2008). However, microscopic models are data-intensive and computationally expensive and hence may not be tractable for real-time control. ...
Road traffic congestion, which occurs when the traffic demand exceeds the operational capacity of the roadway, has become a serious problem all over the world. Traffic signals are effective in managing the traffic demand if properly designed. Traditionally, signal design has been carried out based on the objective of minimizing the overall queue and associated delays at upstream sections and has not considered the effect on downstream sections and midblock regions. Efficiency of signals may be improved if their design takes this factor into account, which is attempted in the present study. In this paper, a control scheme that regulates the traffic density in the downstream section was developed using a macroscopic-model-based approach with traffic density and speed as the state variables of interest. These state variables were estimated based on a Kalman filter approach. The performance of the estimation scheme was corroborated using field data. A closed-loop system with the developed control scheme was implemented in a simulated road stretch developed by integrating microscopic traffic-simulation software and mathematical simulation software. The results from the implementation of the closed-loop system demonstrated the effectiveness of the developed traffic-control scheme. It was observed that the objective of maintaining the density inside the section within the required limit was satisfied.
... A link transmission model for multiple user classes is proposed by Smits, Bliemer, and van Arem (2011). A detailed, heterogeneous simulator is developed for mid block sections and found to be satisfactory in terms of replicating the field conditions (Venkatesan, Gowri, and Sivanandan 2008). However, to reduce the computational complexities, the present study focuses on extending the proposed queue model with holes for mixed tra c rather than addressing more general LWR models. ...
The growing pace of urbanization increases the need of simulators to handle large scale scenarios in reasonable time. The present study presents a fast spatial queue model, which is anchored to an agent-based travel demand simulation framework. The existing queue model is extended to a more realistic behaviour by introducing backward travelling holes. In this approach, the space freed by a leading vehicle is not immediately available to the following vehicle. The resulting dynamics resembles Newell’s simplified kinematic wave model. The space freed corresponding to each leaving vehicle is named as ‘hole’ and, as following vehicles occupy the space freed by leading vehicles, the hole travels backward. This results in triangular fundamental diagrams for traffic flow.
The proposed approach is also extended for heterogeneous traffic conditions. The robust-ness of the model is tested with flow density and average bike passing rate contours. Spatio- temporal trajectories are presented to differentiate the queuing patterns. Finally, a compar-ison of the computational performance of different link and traffic dynamics of the queue model is made.
... However, the main challenges are how to estimate MCDOD in such a way to match multi-source spatiotemporal data in a large-scale transportation network. A number of studies [16,54,43] investigate the multi-class traffic flows in general networks. The multi-class DTA models are studied by Dafermos [10], Yang and Huang [58], Huang and Li [18] without the real-world data validation. ...
Transportation networks are unprecedentedly complex with heterogeneous vehicular flow. Conventionally, vehicle classes are considered by vehicle classifications (such as standard passenger cars and trucks). However, vehicle flow heterogeneity stems from many other aspects in general, e.g., ride-sourcing vehicles versus personal vehicles, human driven vehicles versus connected and automated vehicles. Provided with some observations of vehicular flow for each class in a large-scale transportation network, how to estimate the multi-class spatio-temporal vehicular flow, in terms of time-varying Origin-Destination (OD) demand and path/link flow, remains a big challenge. This paper presents a solution framework for multi-class dynamic OD demand estimation (MCDODE) in large-scale networks. The proposed framework is built on a computational graph with tensor representations of spatio-temporal flow and all intermediate features involved in the MCDODE formulation. A forward-backward algorithm is proposed to efficiently solve the MCDODE formulation on computational graphs. In addition, we propose a novel concept of tree-based cumulative curves to estimate the gradient of OD demand. A Growing Tree algorithm is developed to construct tree-based cumulative curves. The proposed framework is examined on a small network as well as a real-world large-scale network. The experiment results indicate that the proposed framework is compelling, satisfactory and computationally plausible.
... Traffic in India is highly heterogeneous and the traffic flow models reported for homogeneous traffic may not be sufficient to characterize Indian traffic. Studies reported from India are mainly microscopic in nature (Tiwari et al., 2008), (Mallikarjuna and Rao, 2009), (Venkatesan et al., 2008). However, due to the difficulty in calibrating microscopic models they are not preferred for real time applications. ...
Congestion and associated traffic safety are the major challenges for transportation systems all over the world in recent years. Congestion occurs when traffic demand exceeds the operational capacity of the roadway. Better management of infrastructure is required in improving the operational capacity. Traffic signals are one of the most popular traffic control strategies that have been adopted for managing the demand and to reduce congestion; but if not properly designed will lead to excessive delay and increase in travel time. Therefore, signals need to be designed based on theory of traffic flow that requires a good understanding of the traffic system. The present study proposes a macroscopic model based control scheme for Indian traffic conditions. Traffic density and speed are used as the state variables to characterize the system and the developed control scheme regulates the density inside the section.
... Traffic simulation models (TSM) are more significant in capturing the dynamic attribute of transport systems in a way that is not possible with some classic methods. However, micro-simulation users are mainly faced with the problem of appropriate calibration of the utilized software; this problem is a serious one as inappropriate software calibration could produce misleading results which could cause serious problems and irreparable losses [7,8]. ...
The understanding of heterogenous driving conditions can be furthered through microscopic simulation model calibration. This study focused on the calibration of six (6) driving behaviour parameters (standstill distance, look-ahead distance, headway time, following variation, diamond-shape queuing, and look-back distance) for control and simulation of driving behaviour in VISSIM for the prediction of heterogeneous traffic when operating a contra-lane. Driving behaviour simulation at a contraflow operation system is more complicated than mainstream traffic simulation due to the heterogeneous traffic condition at peak hour. The calibrated results in this study were validated and compared to field results using Mean Absolute Percent Error (MAPE) and paired t-test analysis at 95% level of confidence. The validation process showed no observable difference at 98.5% confidence level. Furthermore, standstill distance, headway time, and following variation were found to govern driving behaviour variations. The look-ahead & look-back distances allow smooth and realistic driving manoeuvres in merging & diverging scenarios. Microscopic driving behaviour model enhancement in VISSIM at heterogeneous Asian highway has its benefits in terms of predicting various scenarios as an alternative solution in such traffic.
... process-oriented [9,34] and object-oriented e.g. [35,36] can be used for railway systems. The objectoriented simulation model provides a flexible build-in framework that supports the design process of railway network layout. ...
Delays and disruptions reduce the reliability and stability of the rail operations. Railway traffic rescheduling includes ways to manage the operations during and after the occurrence of such disturbances. In this study, we consider the simultaneous presence of large disruptions (temporary full or partial blockage of tracks) as well as stochastic variation of operations as a source of disturbance. The occurrence time of blockage and its recovery time are given. We designed a simulation-based optimization model that incorporates dynamic dispatch priority rules with the objective of minimizing the total delay time of trains. We, moreover, designed a variable neighborhood search meta-heuristic scheme for handling traffic under the limited capacity close to the blockage. The new plan includes a set of new departure times, dwell times, and train running times. We evaluated the proposed model on a set of disruption scenarios covering a large part of the Iranian rail network. The result indicates that the developed simulation-based optimization approach has substantial advantages in producing practical solution quickly, when compared to commercial optimization software. In addition, the solutions have a lower average and smaller standard deviation than the currently accepted solutions, determined by human dispatcher or by standard software packages.
... Studies reported from India include a few on the use of macroscopic models (Anand, Vanajakshi, & Subramanian, 2011;Padiath, Vanajakshi, & Subramanian, 2010;Padiath, Vanajakshi, Subramanian, & Manda, 2009;Tiwari, Fazio, Gaurav, & Chatteerjee, 2008). Other reported studies have focused on microscopic models that are not suited for real-time applications (Chakroborty & Kikuchi, 1999;Gupta, Chakroborty, & Mukherjee, 1998;Mallikarjuna & Rao, 2009;Mathew, Gundaliya, & Dhingra, 2006;Venkatesan, Gowri, & Sivanandan, 2008). ...
Dynamic traffic flow models are essential for obtaining information about the time evolution of variables describing the traffic flow phenomena and have a critical role in the development and implementation of real-time applications such as Intelligent Transportation Systems (ITS). Macroscopic traffic flow models that treat the traffic as a continuum are preferred for such applications. But, existing macroscopic models characterize homogeneous traffic, and may not be directly applicable to capture the vehicle heterogeneity seen on Indian roads. To address this issue, a non-continuum macroscopic dynamic traffic flow model based on the lumped parameter approach was developed in this study. The model was developed based on the conservation of vehicles equation and a dynamic speed equation incorporating an empirically developed traffic stream model, which is an important contribution of this study. Using this model, an estimation scheme has been developed based on the Kalman filtering technique to estimate traffic states in real time. The proposed scheme was implemented and corroborated for the heterogeneous traffic conditions existing in India. The performance of this scheme has been evaluated and the results obtained have been found to be promising.
... Such models are obviously closer to how real cyclists behave (if properly defined), but are more computationally complex and may require more parametrisation to operate. Venkatesan et al. (2008) developed a continuous space model where heterogeneous (motor vehicle and cyclist) agents move forward along a 'mid-block' (i.e. isolated) link by standard kinematic equations of motion unless they approach the rear of another agent, where they then pass on the side of the forward vehicle to which they are nearer, if there is sufficient space between that vehicle and the boundary. ...
Increased share of urban travel by bicycle is widely desired as a cost-effective and environmentally-beneficial means of travel, and one which has the potential to reduce road congestion and improve health outcomes. Recent rapid cycling growth in cities such as London has served to highlight the lack of robust empirically-backed quantitative literature to inform the practitioner, and the consequential barrier to the delivery of enabling infrastructure of the scale required to meet that demand. Even simple measures vary by orders of magnitude in the literature and some depend on intuitively na¨ıve assumptions, so a simulation (based on the Social Force Model) was defined and implemented to test the key underpinning (non-interaction) assumption of the Highway Capacity Manual’s quantitative definition of cycle level of service. The simulations indicate that an assumption of non-interaction between cyclists results in an outcome intrinsically at odds with fundamental traffic flow theory. Both the literature and simulation process serve to highlight the lack of existing appropriate empirical data and behavioural understanding. Furthermore, collecting such data is difficult, expensive and not easily scalable using current methods. Consequently, a methodology for the collection of key cyclist parameters from generic video data was created, and can be applied to bespoke video surveys and existing CCTV capture, across a variety of modes, and at a fraction of the cost of human operators. In addition, a bicycle simulator is developed which can test cyclist behaviour in a replicable manner and in a range of circumstances. The design and construction process is detailed, and a proof-of-concept, validated against real data, is presented. Subject to some minor improvements identified, the simulator can now be used more widely for the collection of behavioural data. These methodologies provide new and practical capabilities for the collection and application of cyclist data, and a greater understanding of cycle behaviour.
... All the above discussion emphasizes the need to understand the gap acceptance behavior of pedestrians at uncontrolled pedestrian crossings in the presence of heterogeneous traffic. For additional discussion and analysis of different aspects of heterogeneous traffic, see Arasan and Koshy (2005), Venkatesan, Gowri, and Sivanandan (2008), Tang, Huang, Zhao, and Shang (2009), Mathew and Radhakrishnan (2010), Patil and Pawar (in press), and Patil and Sangole (in press). Although there are a few more studies analyzing and modeling heterogeneous traffic, studies on interactions of pedestrians with heterogeneous traffic are limited. ...
Introduction:
Most of the midblock pedestrian crossings on urban roads in India are uncontrolled; wherein the high degree of discretion in pedestrians' behavior while crossing the traffic stream, has made the situation complex to analyze. Vehicles do not yield to pedestrians, even though the traffic laws give priority to pedestrians over motorized vehicles at unsignalized pedestrian crossings. Therefore, a pedestrian has to decide if an available gap is safe or not for crossing.
Method:
This paper aims to investigate pedestrian temporal and spatial gap acceptance for midblock street crossings. Field data were collected using video camera at two midblock pedestrian crossings. The data extraction in laboratory resulted in 1107 pedestrian gaps. Available gaps, pedestrians' decision, traffic volume, etc. were extracted from the videos. While crossing a road with multiple lanes, rolling gap acceptance behavior was observed. Using binary logit analysis, six utility models were developed, three each for temporal and spatial gaps.
Results and conclusions:
The 50th percentile temporal and spatial gaps ranged from 4.1 to 4.8s and 67 to 79 m respectively, whereas the 85th percentile temporal and spatial gaps ranged from 5 to 5.8s and 82 to 95 m respectively. These gap values were smaller than that reported in the studies in developed countries. The speed of conflicting vehicle was found to be significant in spatial gap but not in temporal gap acceptance. The gap acceptance decision was also found to be affected by the type of conflicting vehicles.
Practical applications:
The insights from this study can be used for the safety and performance evaluation of uncontrolled midblock street crossings in developing countries.
... However, this assumption contradicts research findings showing that lane change durations are in the range of 1.0-16.5 s in the case of homogeneous traffic conditions (Worrall and Bullen 1970;Finnegan and Green 1990;Chovan et al. 1994;Hetrick 1997;Tijerina et al. 1997;Hanowski 2000;Toledo and Zohar 2007;Moridpour et al. 2010b;Cao et al. 2013). Lateral shifts are modeled as an instantaneous process in traffic simulation models developed for mixed traffic conditions (Arasan and Koshy 2003;Kanagaraj et al. 2008;Asaithambi et al. 2009;Mallikarjuna and Rao 2011;Mathew et al. 2013;Asaithambi et al. 2016). Munigety et al. (2014) reported that lateral movement duration varies from 3 s (two-wheelers) to 12 s (threewheelers). ...
Traffic on urban roads in developing countries is characterized by wide mix of vehicles
with loose lane discipline which results in parallel movement of vehicles on the same
lane and hence, vehicles not only interact longitudinally with the vehicles ahead but
also laterally with vehicles on its sides. Lateral movements have significant impact on
the characteristics of traffic flow and hence are of great importance in microscopic
traffic simulation models. The existing simulation model for mixed traffic conditions
model the lateral shifts (lateral movements) as an instantaneous process but neglect
the detailed modeling. However, research indicates that the duration for lateral shifts is
generally in the range of 0.5 s to 15 s. The omission of lateral shift duration from
simulation models may have a significant impact on simulation outputs. Also, it is
believed that different vehicle types have different lateral shift duration due to their
variations in the physical and operational characteristics. Hence, in this paper an
attempt is made to develop vehicle-specific lateral shift duration model by considering
different explanatory variables such as direction of lateral shift, available space gaps,
speeds of subject vehicle and surrounding vehicles, vehicle types, clearance, etc. The
models were estimated by using the trajectory data collected during medium flow
conditions from an urban arterial in Chennai city, India. The findings from this study
have direct implications on modelling lateral shits in microscopic traffic simulation to be
developed specifically for mixed traffic conditions.
... The validity of these simulation model depends on how the model incorporates the various field data like the vehicle arrivals, the speed etc., which greatly influence the solution of traffic problems. Significant amount of research has been carried out in developing simulation models to address the above problems related to mixed traffic conditions on divided roads [1][2][3][4][5][6][7][8][9][10][11][12]. ...
Most of the Indian urban roads are bi-directional in
nature consists of mix up of different vehicle types with weak lane
discipline. A mathematical or analytical treatment of such
condition is found infeasible due to its complex nature. Hence,
simulation has become inevitable tool for analysis and
interpretation of such real world situations. There are only few
studies which focuses exclusively on developing a bidirectional
traffic simulation model considering the longitudinal and lateral
behaviour of vehicles for urban undivided roads. With the above
motivation, the present study focuses on development of simulation
models for bi-directional mixed traffic flow using object oriented
programming (OOP) concepts. The proposed model would be of
significant assistance to traffic engineers while making key
decisions in traffic control and management policies
... These vehicles significantly vary in the static characteristics (such as length, width, and size) and dynamic characteristics (such as acceleration/deceleration and maximum speed). The acceleration/deceleration characteristics will affect the gap required for safe stopping and thereby the gap a vehicle maintains (Kanagaraj et al. 2008;Asaithambi et al. 2009). Lan and Chang (2004) used General Motors model to explain the motorcycle's following behaviours in two situations: (1) only one leading vehicle in front; (2) two or more leading vehicles in front and neighbouring-front (including either left-front, right-front, or both). ...
Car following models replicate the behaviour of a car following another car. In mixed traffic conditions, leader-follower vehicle types are not only car-car cases but also there are different combinations of vehicles (e.g., car-two wheeler and heavy vehicle-auto-rickshaw). Due to weak lane discipline, the follower is unable to strictly follow the lead vehicle. The other types of following behaviour like staggered following, following between vehicles, etc. are also observed under mixed traffic conditions. Depending on speed and position of vehicles in front, the subject vehicle may follow a leading vehicle with varying levels of lateral separation or stagger. The nature, extent and impact of such interactions need to be investigated for characterizing following behaviour under mixed traffic conditions. Hence, the present study focuses on analysis and modelling of vehicle following behaviour under mixed traffic conditions.
... These vehicles significantly vary in the static characteristics (such as length, width, and size) and dynamic characteristics (such as acceleration/deceleration and maximum speed). The acceleration/deceleration characteristics will affect the gap required for safe stopping and thereby the gap a vehicle maintains (Kanagaraj et al. 2008;Asaithambi et al. 2009). Lan and Chang (2004) used General Motors model to explain the motorcycle's following behaviours in two situations: (1) only one leading vehicle in front; (2) two or more leading vehicles in front and neighbouring-front (including either left-front, right-front, or both). ...
Car-following models replicate the behaviour of a driver following another vehicle. Such models can find applications in traffic simulation models and can be used to evaluate traffic flow characteristics, analysis of safety and capacity analysis. Traffic on Indian roads is highly mixed in nature with widely varying static and dynamic characteristics of vehicles. Vehicles can occupy any available road space due to non-lane discipline. Moreover, small sized vehicles use gaps between larger vehicles in the traffic stream. In mixed traffic conditions, leader-follower vehicle types are not only car-car but also there are different combinations of vehicles (e.g., two wheeler-car, bus-auto rickshaw, and truck-two wheeler). Due to non-lane discipline and variations in the static and dynamic characteristics of vehicles, the following behavior of vehicles are different compared to homogeneous and lane-based traffic. The present study focuses on analysis of different types of following behavior using trajectory data collected in Chennai city. The vehicle following behavior was classified into three different types such as car following, staggered following and following between two leaders based on the size of follower and extent of overlap. From the statistical analysis, it was inferred following behaviors are different for different types of vehicles. This study has interesting implications in identifying vehicle specific and vehicle following parameters for car following models to be adopted under mixed traffic conditions.
... They often adapt these one-dimensional models for "disorderely" streams by dividing lanes into narrow artificial longitudinal strips (or in CA-based approaches use artificially narrow cells) which tend to reduce the suddenness of lane-changing. Attempts are also made by Arasan and Koshy 2 and Venkatesan et al. 51 who use an overtaking maneuver strategy (where the maneuver is represented through instantaneous lateral shifts to "adequate" gaps to the left or right of the subject vehicle) with certain primitive car-following strategy (where speed of the subject/following vehicle is equated with that of the leading vehicle if overtaking is not possible) to represent the effect of disorderliness in traffic streams. Further, as an aside, it must be mentioned that most of these tools use a large number of user-specified parameters whose values are often difficult (if not impossible) to uniquely identify from real-world data. ...
Disorderly traffic streams are those that, simply stated, do not have parallel lines (or lanes) of vehicles but have vehicles distributed more haphazardly in the road space. Vehicles in such streams, while moving longitudinally, change their lateral positions frequently. Their trajectories have a more pronounced wander along the width or the lateral dimension as opposed to those vehicles that primarily move in lanes. This property of disorderly streams dictates that its mathematical models must admit two spatial dimensions (the longitudinal and the lateral). Further, the observed impact of road geometry features like width, curvature, etc., on stream behavior, irrespective of whether the stream is disorderly, also suggests that realistic models of traffic streams must describe the streams using two spatial dimensions. Unfortunately, most of the theories of traffic dynamics are one-dimensional—they only consider the longitudinal dimension. This paper, while describing many of the existing approaches to modelling vehicular traffic behavior builds a case for strengthening two-dimensional modelling approaches that are all, still in their infancy. Given the (1) large increase in computation and data handling capabilities over the last decade and (2) significant strides made in developing tools for observing traffic dynamics at scales and accuracy levels that were previously unimaginable, the authors believe the time has come to develop, calibrate and validate reasonable two-dimensional models of traffic dynamics.
... At the same time, the authors are not referring to the mixed traffic of autonomous and human-driven vehicles. To understand the driving behavior in mixed traffic conditions, research attempts (Venkatesan, Gowri, and Sivanandan 2008;Mallikarjuna and Rao 2011) were carried in recent times. In this direction, Kanagaraj et al. (2015) highlighted the importance of lateral behavior in mixed traffic conditions. ...
This study aims to model traffic flow under weak lane-based heterogonous (mixed) traffic conditions. Unlike homogeneous traffic, when a follower (subject) vehicle in mixed traffic moves closer to its leader vehicle, it tends to adjust its longitudinal movement or change its lane and acts discretely. Due to this phenomenon, traffic flow modeling under such conditions is always challenging. A new driver behavioral logic is conceptualized for the vehicles' movement within a combination of surrounding vehicles. In which the following behavior was dissected with the lateral shift distance between vehicles. Two car-following models for homogeneous traffic conditions, the IDM and Gipps models were adapted with relevant lateral behavior parameters to different vehicle classes under mixed-traffic conditions. The new driving behavior logic was incorporated externally in place of default logic. The results showed that the performance of the adapted models was better accurate than the classical models.
... Microscopic traffic simulation models, for example, the cellular automata (CA) based traffic simulation model developed by Meng and Weng (2011), are useful as they allow traffic engineers to accurately estimate work zone capacity so that effective traffic management strategies can be employed to mitigate traffic delays in work zones. In microscopic traffic simulation models, headway generation is an important task and thus, deriving an accurate distribution model is a key step towards simulating traffic realistically (Venkatesan, Gowri, and Sivanandan 2008;Mallikarjuna and Rao 2011). Therefore, it is of utmost importance to analyse the proper vehicle headway distributions so that they can be used to accurately generate vehicle dynamics in work zones. ...
This study investigates work zone vehicle headway distribution by disaggregating the vehicle headways into four types: car–car, car–truck, truck–car and truck–truck. It first confirms that the four types of vehicle headways are significantly different by performing the Kruskal–Wallis and Mann–Whitney tests using work zone headway data from Singapore. The statistical test results further show that four factors – traffic flow rate, percentage of trucks, work intensity and lane position – have a significant impact on each type of vehicle headway in work zones. A useful methodology is thus proposed to determine the best-fitted headway distribution model for each type, which includes two procedures: determining the best distribution pattern for each type using the maximum-likelihood estimation and Kolmogorov–Smirnov test techniques and formulating the distribution model parameters as a function of the aforementioned four factors.
... Previous studies have reported the ineffectiveness of conventional traffic flow models for capturing the peculiarities of disordered heterogeneous traffic Koshy 2003, 2005;Logghe 2003;Nair, Mahmassani, and Miller-Hooks 2011;van Lint, Hoogendoorn, and Schreuder 2008;Venkatesan, Gowri, and Sivanandan 2008). Though some studies (Arasan and Koshy 2003;Nair, Mahmassani, and Miller-Hooks 2011) emphasized the pivotal role of PTWs in altering the traffic characteristics, their investigation was either focused on capturing the overall changes in traffic characteristics at the macroscopic level or examining the speed and headway distributions of the prevailing traffic stream. ...
This article reports a systematic investigation carried out to model the lateral movement decisions of Powered-Two-Wheelers (PTWs) in disordered heterogeneous traffic conditions. The lateral maneuvering decisions of PTWs were framed as a typical multiclass classification problem, and significant factors governing such decisions were identified. Four machine learning models, along with the statistical model, were built to achieve this objective. The comparative analysis regarding the predictive performance of these models shown that the random forest model outperforms the rest of the considered models in terms of its classification power. To this end, the results from this investigation revealed that the lateral movement pattern of PTWs could be predicted using speed and spatial information of its surrounding vehicles. Interestingly, this information can be seamlessly collected with some sensors presently deployed in the advanced vehicles. Thus, the developed models would help in the design of active safety and driving assistance systems for such vehicles.
... As a result, due to the chaotic traffic nature, safety in the mixed-traffic stream has been a major concern and the possibility of performance degradation. On the other hand, to overcome the challenge of traffic simulation in mixed traffic conditions, researchers conceptualized object-oriented programing (Arasan and Koshy 2005;Kotagi and Asaithambi 2019;Venkatesan, Gowri, and Sivanandan 2008) and strip based tactics (Mallikarjuna and Ramachandra Rao 2011;Mathew, Munigety, and Bajpai 2015) to mimic the mixed traffic conditions. Further, very few notable studies have been carried to address the problems of mixed traffic. ...
In heterogeneous (mixed) traffic stream, there are different vehicle categories with ensuing non-lane disciplined traffic that affect the traffic stream's safety and throughput.
Impacts of establishing separate lanes for motorized two-wheelers (MTW) are evaluated using microscopic traffic simulation. Traffic management scenarios for lane-utilization of vehicles were evaluated in terms of safety and traffic efficiency under prevailing mixed traffic conditions. It is observed that, with dedicated MTW lanes, the capacity has increased by 17 percent in comparison to the base scenario. The underlying logic involved in the scenarios was about segregating smaller vehicles. The results showed that the segregation of small vehicles could substantially improve the mixed traffic stream's performance and had a little impact on safety. Interestingly, the severe collision percentages are anticipated to be dropped down significantly from 1.2 and 1.4 to zero. Therefore, this study recommends dedicated lanes for MTW to address mixed-traffic problems on multilane urban corridors.
... In developed software, off-the-shelf software has certain drawbacks and hence, to overcome these issues, the researcher has to rely on the programming interface of the software. On the other hand, few researchers developed simulation models for midblock sections under disordered traffic conditions Venkatesan, Gowri, and Sivanandan 2008;Asaithambi et al. 2012;Metkari, Budhkar, and Maurya 2013;Asaithambi et al. 2018). However, these models did not focus on investigating the effect of side frictions on PCU. ...
Representation of traffic in terms of Passenger Car Unit (PCU) is imperative to estimate capacity in disordered traffic. Many studies have been conducted on investigation of impacts of traffic and geometric conditions on traffic characteristics and PCUs. However, the sensitivity of PCUs due to roadside frictions are not adequately studied. To address this gap, this study aims to estimate PCU values for vehicles under the influence of curbside bus stop, which is the most common roadside friction in developing countries. Lack of space for providing exclusive bus bays and higher demand for public transport buses in urban roads justify the need for this study. Methodology of this study involves development and validation of a microscopic simulation model to quantify the impact of curbside bus stop on PCU as well as capacity. The results indicate the significant differences in PCU values due to the presence of curbside bus stop with varying traffic volume and composition.
... However, the main challenges are how to estimate MCDOD in such a way to match multi-source spatio-temporal data in a large-scale transportation network. A number of studies (Gundaliya et al., 2008;Venkatesan et al., 2008;Qian et al., 2017) investigate the multi-class traffic flows in general networks. The multi-class DTA models are studied by Dafermos (1972), Yang and Huang (2004), Huang and Li (2007) without the real-world data validation. ...
Transportation networks are unprecedentedly complex with heterogeneous vehicular flow. Conventionally, vehicles are classified by size, the number of axles or engine types, e.g., standard passenger cars versus trucks. However, vehicle flow heterogeneity stems from many other aspects in general, e.g., ride-sourcing vehicles versus personal vehicles, human driven vehicles versus connected and automated vehicles. Provided with some observations of vehicular flow for each class in a large-scale transportation network, how to estimate the multi-class spatio-temporal vehicular flow, in terms of time-varying Origin-Destination (OD) demand and path/link flow, remains a big challenge. This paper presents a solution framework for multi-class dynamic OD demand estimation (MCDODE) in large-scale networks that work for any vehicular data in general. The proposed framework cast the standard OD estimation methods into a computational graph with tensor representations of spatio-temporal flow and all intermediate features involved in the MCDODE formulation. A forward-backward algorithm is proposed to efficiently solve the MCDODE formulation on computational graphs. In addition, we propose a novel concept of tree-based cumulative curves to compute the exact multi-class Dynamic Assignment Ratio (DAR) matrix. A Growing Tree algorithm is developed to construct tree-based cumulative curves. The proposed framework is examined on a small network, a mid-size network as well as a real-world large-scale network. The experiment results indicate that the proposed framework is compelling, satisfactory and computationally plausible.
... All the above discussion underlines the need to understand crossing behavior of pedestrian, gap acceptance at uncontrolled mid-block crossings locations in the presence of mix traffic condition. More analysis and explanations of different aspects of heterogeneous traffic by [6]- [9] Several researches investigated the pedestrian's gap acceptance behavior in developed countries. They discovered an effect of some factors such as gender, pedestrian waiting time, frequency of attempt, grope crossing and type and speed of vehicle, etc. ...
Gap acceptance behavior of pedestrian is significant to Safety and crash of pedestrian. The issue of gap acceptance by pedestrians is relevant for road safety. It is novel to analyze the gap acceptance behavior and the effects of selected factors based on observation survey. Many studies examined the mid-block crossing behavior of pedestrians in the developed country. In contrast, this study is one of the first to analyze and model the crossing choice behaviors of pedestrians within an entire Malaysia. However, the main aim of this paper is to investigate and model non-compliant pedestrians' traffic gap acceptance at unsignalised pedestrian mid-block crossings in Malaysia. For this purpose, a field survey was carried out using videotaped data. Gaps size accepted, number and size of the rejected gaps are examined against pedestrians' and traffic attributes, using statistical analysis (SPSS.22) and modeling approach (Multiple linear Regression and Binary logit regression). In addition, Critical gap were determined using Raff's method. The results reveled that seven factors that influence the pedestrian crosing behaviour in terms of accepted gap size in seconds. Results showed traffic speed, pedestrian waiting time, vehicle size, pedestrian gender, crossing distance, age group, and pedestrian number are the significant factors for accepted gap size of pedestrian in Batu Pahat. Pedestrian waiting time was found to have negative impact on gap size acceptance while the remaining factors showed positive influence on the gap size acceptance. In the development of crossing choice model in Batu Pahat, traffic speed, driver yield, pedestrian number and pedestrian age group are the significant influencer for pedestrian choice. Raff's method result shows the critical gap size value is approximately 12.5 seconds, which is quite similar to reported in previous studies. These outcomes would be recommended to use in the evaluation of unprotected mid-block crosswalks and designing of new crosswalk facility in Malaysia.
... These vehicles significantly vary in the static characteristics (such as length, width, and size) and dynamic characteristics (such as acceleration/deceleration and maximum speed). The acceleration/deceleration characteristics will affect the gap required for safe stopping and thereby the gap a vehicle maintains (Gowri et al. 2009;Venkatesan et al. 2008). Further, the following behavior of a driver depends on both the type of leader and follower vehicle. ...
Car-following behavior forms the kernel of traffic microsimulation models and is extensively studied for similar vehicle types. However, in heterogeneous traffic having a diverse mix of vehicles, following behavior also depends on the type of both the leader and following vehicles. This paper is an attempt to modify the widely used Gipps's car-following model to incorporate vehicle-type dependent parameters. Performance of the model is studied at microscopic and macroscopic levels using data collected from both homogeneous and heterogeneous traffic conditions. The results indicate that the proposed modifications enhance the prediction of follower behavior and suggest the need of incorporating vehicle-type combination specific parameters into traffic simulation models. DOI: 10.1061/(ASCE)TE.1943-5436.0000273. (C) 2011 American Society of Civil Engineers.
... A dynamic model was developed by Tang et al. from the relationship between the microscopic and macroscopic variables for heterogeneous traffic [11]. Arasan et al. [12] and Venkatesan et al. [13] developed microscopic simulation model for heterogeneous traffic. The principles of Cellular Automata were applied to model heterogeneous traffic in [14] and [15]. ...
Managing congestion in mixed traffic conditions, characterized by heterogeneous and lane-less traffic, is a challenging task. Traditionally density, defined as the number of vehicles in a road stretch, is used to quantify congestion. However, direct measurement of density is difficult and hence is usually estimated from other variables. In this paper, a relationship is derived between traffic density and area occupancy, a variable that can incorporate heterogeneity and lane-less movement. Using the derived density-area occupancy relation, a non-continuum macroscopic single state linear time varying model was developed. Estimation of density was done by using the Kalman filtering technique and corroborated with simulated density. The need for dynamic estimation is motivated by evaluating the performance of two static estimation schemes in the presence of uncertainties. Performance was tested for different traffic scenarios such as congestion and non-recurrent traffic incidents. Further, to improve the estimation accuracy in scenarios involving transitions in traffic conditions, an adaptive estimator was developed. It was found that the adaptive estimator provided the best estimation accuracy.
... A comprehensive review on non-lane based traffic was made by Khan and Maini (1999): the unique characteristics of traffic composition, driver behavior, roadway geometry, maneuverability, and vehicular interactions were presented in model studies of heterogeneous traffic flow. Simulation of heterogeneous traffic on urban roads in Chennai City, India was also carried out by Venkatesan et al. (2008). The research revealed that the approach was satisfactory to replicate the field conditions based on headway distribution and speeds of different types of vehicles. ...
... Though comprehensive commercial software is not yet available for studying heterogeneous traffic, attempts have been made by researchers to model various aspects of such traffic. A review of the literature shows that only limited studies have been done to develop a simulation model for intersections under heterogeneous traffic conditions [6][7][8][9][10][11][12][13][14]. ...
Modeling traffic flow is stochastic in nature due to randomness in variables such as vehicle arrivals and speeds. Due to this and due to complex vehicular interactions and their manoeuvres, it is extremely difficult to model the traffic flow through analytical methods. To study this type of complex traffic system and vehicle interactions, simulation is considered as an effective tool. Application of homogeneous traffic models to heterogeneous traffic may not be able to capture the complex manoeuvres and interactions in such flows. Hence, a microscopic simulation model for heterogeneous traffic is developed using object oriented concepts. This simulation model acts as a tool for evaluating various control measures at signalized intersections. The present study focuses on the evaluation of Right Turn Lane (RTL) and Channelised Left Turn Lane (CLTL). A sensitivity analysis was performed to evaluate RTL and CLTL by varying the approach volumes, turn proportions and turn lane lengths. RTL is found to be advantageous only up to certain approach volumes and right-turn proportions, beyond which it is counter-productive. CLTL is found to be advantageous for lower approach volumes for all turn proportions, signifying the benefits of CLTL. It is counter-productive for higher approach volume and lower turn proportions. This study pinpoints the break-even points for various scenarios. The developed simulation model can be used as an appropriate intersection lane control tool for enhancing the efficiency of flow at intersections. This model can also be employed for scenario analysis and can be valuable to field traffic engineers in implementing vehicle-type based and lane-based traffic control measures.
One of the most popular intelligent transportation systems (ITS) applications is to provide real-time road traffic congestion information to the users. Traffic density is a major congestion indicator, and because its measurement is difficult, it is usually estimated from other readily measurable parameters. Several studies have explored various approaches for density estimation for homogeneous and lane-disciplined traffic conditions. However, Indian traffic is different with its heterogeneity of traffic and absence of lane discipline. Another characteristic is the lack of access control, making automated measurement of net entry into a study section difficult. An added difficulty is that the roads in India are not yet equipped with traffic sensors, leading to limitation in data collection. The present study mainly addresses the issue of estimating traffic density in the absence of automated sensors at the side roads/ramps on Indian roadways. A lumped parameter macroscopic traffic flow model has been formulated, and using this model, a model-based estimation scheme has been designed based on the Kalman filtering technique. The only data required for implementing this method in the field are the flow passing the entry location and the spot speeds of vehicles passing through the entry and exit locations. The proposed method was corroborated using data measured from a road stretch in Chennai, and the performance was found to be satisfactory.
This article investigates traffic flow at a T-shaped unsignalised intersection based on the cellular automaton (CA) simulation. This approach can reveal many microscopic features of traffic flow. We used a refined Nagel–Schreckenberg model and the geometry of the intersection has been considered, in which vehicles are assumed to move along 1/4 circle arcs in the intersection. Yield rules need to be obeyed when conflict occurs. Three-dimensional (3D) visualisations have been created with the support of an OpenGL, which gives more user-friendly and realistic presentations. We have presented the diagrams of intersection states and studied the capacities of different approaches. Our method is expected to become a general approach for CA simulation of intersections.
Accurate estimation of traffic in intelligent transportation system applications, such as the advanced traveler information system and the advanced traffic management system, requires fixed location-based measurements, vehicle-based measurements, or both. Using both data sources is too expensive for most government agencies, especially in developing countries such as India, and also leads to issues related to installation and maintenance, especially on urban roads. The main drawback of vehicle-based measurements is the potential lack of participation because of privacy concerns; lack of participation would limit data collection to a sample of the population, primarily on public transport vehicles. The study aims to overcome such difficulties by using only location-based flow data for the estimation of spatial parameters, such as density and travel time. These parameters are difficult to measure or estimate on an urban arterial, especially under heterogeneous traffic conditions, because of lack of lane discipline and because of complex interactions among different vehicle types. The Lighthill-Whitham-Richards macroscopic traffic flow model discretized in both space and time was employed in the estimation scheme. The resulting partial differential equations were solved numerically with the finite difference formulation of forward time backward space. Both linear and exponential speed density relationships were considered and incorporated into the macroscopic model. Linear and cubic spline interpolations of input flow values were compared. The estimated density was corroborated with the density obtained from input output analysis. Estimated travel times were compared with manually observed travel times and travel times obtained from probe vehicles fitted with Global Positioning System devices.
Traffic flow in many developing countries is strongly mixed comprising vehicle
types, such as motorcycles, cars, (mini) buses, and trucks; furthermore, traffic flow typically
exhibits free inter-lane exchanges. This phenomenon causes a complex vehicle interaction,
rendering most existing traffic flow modeling approaches insufficient and requiring a new
approach. New approaches to the heterogeneous non-lane-based flow have been proposed but
empirical verification has been lacking. To bridge this gap, this paper presents some
preliminary analyses on a data set collected from a number of road sections in the city of
Surabaya, Indonesia. Video data is used to capture aspects of vehicle interaction. Using the
porous flow approach, we investigate aspects related to the pore size-density distributions and
class-specific critical pore sizes.
While modern roundabout has been proven superior to signalized intersection in safety, delay, and capacity under homogeneous traffic, its merits in heterogeneous traffic are neither proven nor analyzed. Both unique characteristics and models to reproduce behaviors in simulation has not been discussed comprehensively, especially in the high proportion of two-wheeler (TW) condition. In this background, the study aims to answer the question of how to reproduce unique characteristics of TW at roundabout in simulation. In order to achieve the answer, the study has gone through the below procedures step by step.
Firstly, chapter 1 presents background, research needs, research gap, research question, objectives and scope. In chapter 2, the literature review section determined the two constitutions of mixed traffic that are the performance rule and the appearance of the small-sized vehicle. Traffic in Ho Chi Minh city, Vietnam, satisfies both two conditions and has a uniqueness that only one type of small-sized vehicle as well as non-lane-based vehicle, TW, also named as motorcycle, and its dominance in traffic proportion. Thus, roundabouts in the city are selected as case studies. Moreover, this section also goes through the concepts and techniques related to model development, collective behavior, two-player game theory, agent-based modeling.
Secondly, the surveyed videos are recorded by unmanned areial vehicle (UAV), DJI Phantom 4 Pro, and the trajectory data is extracted by using semi-automated software. The accuracy of extracted data is examined with under 3.4% error. From extracted data, the macroscopic and microscopic characteristics of TWs are analyzed. Chapter 3 highlights three points that are the exponential relationship between turning angle rate and speed, the small critical gap of TW, 1.25 seconds, and the oval shape of the following space.
Chapter 4 presents the model development in detail and its components. Based on the collective behavior and game theory, the TW’s interaction model is built at the microscopic level, including regular movement model, conflict-solving model, and collective behavior model. The implementation of the model in traffic simulator is detailed in chapter 5. The simulator is built based on the multi-agent programmable modeling environment, Netlogo. The parameters are calibrated using half of the collected data.
Chapter 6 presented a series of results and indicators for validating the developed simulator. The remaining collected data is using for validation. Totally nine indicators are used for both macroscopic and microscopic validation. The total turning angle and low-speed duration are uniquely proposed in this study for validation. In total, the developed simulator is validated as good in representing both macroscopic and microscopic characteristics. The developed simulator is superior to the popular commercial software for heterogeneous traffic, PTV VISSIM, in simulating heterogeneous traffic at the roundabout.
Finally, chapter 7 concluded the study’s achievements, contributions, and limitations. Concerning research interest, the study proposed the novel TW’s interaction model at the individual level. The model potentially applies and expends in the future to improve the accuracy of the future microscopic simulations. In addition, the developed agent-based simulator also has practical contributions. It could be a useful tool for measuring the current roundabout performance under different schemes, or for policy test as well as new geometric design test.
Probabilistic Neural Network (PNN) and Adaptive Neuro Fuzzy inference System (ANFIS), are two
of the most advanced Neural Network (NN) architecture available to model different transportation
data sets involving significant human interactions. In this study, PNN and ANFIS are applied to
develop bus Service Quality (SQ) prediction model based on user stated preferences. Using a data set
extracted from 655 questionnaire survey samples, this study has developed bus SQ prediction model
using 22 attributes for urban context. A comparison on the prediction capability of PNN and ANFIS is
presented. From the analysis, ANFIS is found to out-perform PNN in prediction capability. Selected
22 SQ attributes are ranked according to their significance in the developed model, to identify the key
attributes affecting the bus SQ. “Punctuality and Reliability”, “Seat Availability”, and “Service
Frequency” are found to be the top three attributes that mostly affect the decision making process of
the bus service users. This study can help the bus service providers and the public transport authority
to identify and improve the quality of significant attributes, and thereby, increase bus transit ridership.
Classical traffic flow models cannot be readily applied in heterogeneous traffic systems owing to the complex nature of their traffic dynamics. This paper develops a stochastic macroscopic model for traffic state estimation and short-term prediction in such systems. The proposed model takes into account the wide variation in the operating and performance characteristics of vehicles in heterogeneous condition through the use of variable fundamental diagrams (FDs) for different links. The model also allows for the underestimation of flow and speed due to the effect of vehicular influence area in the stated traffic condition. For this, normally distributed stochastic state influencing terms are used with the basic state estimation equations. In addition, an empirical
parameter is introduced in the speed dynamics of the model to capture the sensitivity of traffic speed to the speeds of multiple leaders in a heterogeneous mix. To confirm the structure of the FD, initially the speed-density plots of the field data for different links are fitted with four general structures: namely, the linear, logarithmic, exponential and polynomial forms. It is revealed that 13
the 3rd degree polynomial structure is best suited for prevailing traffic condition. The optimized
link-specific parameters of the model comply with those obtained from the regression analysis. Field validation with high-resolution traffic data proved that the proposed model can capture traffic dynamics quite accurately. To determine the individual contributions of the proposed model features, different structural variations of the final model are also investigated.
In India, traffic on roads is highly mixed in nature with widely varying static and dynamic characteristics of vehicles. Also, vehicles do not follow strict lane discipline and occupy any available lateral position on the road space. In most of the cities in India, mixed traffic is dominated by high proportion of motorcycles. Under these conditions, expressing traffic volume in terms of Passenger Car Unit (PCU) by considering passenger car as the standard vehicle will be inappropriate. This study investigates the methodology developed by Minh et al. (2009) to estimate the Motorcycle Unit (MCU) by considering dynamic characteristics of moving vehicles such as speed and effective space. The concept of MCU values was introduced by considering motorcycle as the basic vehicle in the traffic flow.
Data for this study was collected on mid-block sections of four-lane divided urban roads located in India, where motorcycle proportion is highly dominant. MCU is expressed as the relationship between speeds and effective spaces with respect to motorcycles and other types of vehicles. The effective spaces between the subject vehicle and surrounding vehicles were obtained and it was found that the effective space of each vehicle increases with the increase in speed of vehicles. Also, it was found that MCU is a function of the mean speed and mean effective space of each type of vehicle.
The estimated MCU values for car, auto rickshaw, bus, and LCV (light commercial vehicle) were 2.26, 1.81, 6.41 and 3.20, respectively. These values were validated with previously developed methods and found that adopted methodology is accurately determining the MCU values for different types of vehicles in mixed traffic that dominated by motorcycles on mid-block sections of urban roads. The findings obtained from this research can be used to develop the speed-flow relationship, estimate highway capacity and formulate effective traffic control and management measures.
Travel-time information is an integral part of Advanced Traveler Information Systems and Advanced Traffic Management Systems. Real-time estimation of stream travel time will be helpful in making trip decisions such as route choice and departure time. The present study proposes a method to predict stream travel time using particle filtering approach which considers the predicted stream travel time as the sum of the median of historical travel times, random variations in travel time over time, and a model evolution error. The present model hypothesizes the median of historical travel times obtained from the collected data as a priori estimate and hence predicting the actual travel time will be equivalent to forecasting the variations in travel time according to the current measurements. In order to capture the random variations in travel time, a dynamic mathematical modeling approach with particle filtering technique is used. The results obtained from the implementation of the above method are compared with the measured travel time data and the prediction accuracy, quantified using the Mean Absolute Percentage Error and Mean Absolute Error was observed to be satisfactory. Performance of this method was compared to a basic speed-based approach, where travel time is obtained by time–distance relationship using space-mean speed, and the proposed method showed better performance.
Modelling of traffic flow lacking lane-adherence, with variable vehicle sizes and speeds, is a pressing issue in the simulation field. Commercially available software is not designed for modelling such traffic, which is characteristic of developing countries. A recently developed method is to model traffic as grains of sand moving through a porous medium. This approach is explored and expanded in this work to consider multiple vehicle classes and potential uses in microsimulation. A microsimulation model is developed using an object-oriented approach and compared with existing work in the field. The developed approach, found to fit with the porous flow approach, is shown to properly reflect the traffic flow impacts associated with introducing additional vehicle classes. Fundamental flow diagrams are presented for heterogeneous traffic, which fit a Daganzo approximation. It is determined that several changes are required to the theoretical framework to accurately represent traffic characteristics before viable commercial application.
Vehicle trajectory data obtained from the semi-automated trackers are prone to white Gaussian noise along with the outliers originated from the occlusion and the other possible human errors. Locally weighted polynomial regression (LWPR) is one of the methods used to smooth the observed vehicle trajectories. The window size, polynomial order, and the weight function are the parameters required for performing the LWPR. Window size and polynomial order primarily control the bias-variance trade-off between the actual and the estimated trajectory. In this study, a method is proposed to identify the optimal window size and polynomial order, considering the dynamics of individual vehicles. The proposed method assumes that the actual trajectory is smooth and continuous and all the observed data points may not be falling on the actual trajectory. Optimum window size was estimated by converging the estimated Mean Squared Error (MSE) to the actual MSE. This procedure minimizes the effect of polynomial order on the bias-variance trade-off. The optimum polynomial order was found through quartile analysis of the MSE corresponding to the optimum window size. We have considered third quartile error value for estimating the optimal polynomial order. The trajectory reconstructed through this approach produces better results in the consistency analysis.
Two-lane two-way urban streets play a significant role in the transportation system. Due to the high mixture of traffic flow, few models are capable of describing the complex interaction with multiple types of agents involved. This paper proposes a Strategy Selection and Transition (SSAT) model formulated as a hierarchical ‘Motivation-Decision-Action’ framework. The motivation layer uses the Risk-Motion-Field to select a driving strategy as the driving intention. Then, the decision layer dynamically adjusts the intention through the strategy transition embodied in a well-defined Finite-State Machine. Finally, in the action layer, a set of corresponding operational models specify the decided behavior into control parameters. As per our numerical test, SSAT model outperforms VISSIM and TransModeler, which are two widely-used simulation software, at the macroscopic level. Besides, overtaking-distance ratio and trajectory distribution replicate the evidence of the highly mixed traffic flow. In addition, the case study is also satisfactory.
This paper discusses the development of a novel off-line vision-based system to obtain the naturalistic trajectory database of traffic streams from recorded video footages. The developed system uses a semi-automatic mechanism that provides manual interference for vehicle identification and classification and executes automated tracking of the identified vehicles. A trajectory database of typical disordered heterogeneous traffic stream was collected to evaluate the performance of the developed system. Results show that the developed system significantly enhances the process of trajectory data collection in such traffic conditions. The collected trajectory database is then used to investigate two crucial aspects that characterize the disordered heterogeneous traffic (i) interaction of different types of vehicles in the longitudinal and staggered following scenario, and (ii) lateral shift propensity of different types of vehicles. The analysis emphasizes the behavioral difference between different types of vehicles, and utility of the developed system to address the prevailing research gaps.
Road segments using traffic markings to separate the vehicle lane and the adjacent bicycle lane are widely adopted on urban roads. Bicycles’ illegal lane-changing behavior (ILC) is commonly observed on such road segments, resulting in severe influences of traffic efficiency and bringing hidden dangers. However, existing models disregard different categories of ILC and heterogeneities of ILC between electric bikes (e-bikes) and regular bikes (r-bikes), which has limitations in representing the realistic ILC. To address these disadvantages and understand how heterogeneities affect the ILC, this paper analyzes the behavioral characteristics of ILC using field data and proposes a new cellular automaton (CA) model. Corresponding rules are set for different categories of ILC in the model, and simultaneously the bicycle heterogeneities of ILC are also considered in rules-making. Simulation results indicate that as the proportion of e-bikes increases, the frequency of ILC increases. Furthermore, vehicle volume decreases due to the occurrence of ILC, and the effect is more evident with a higher proportion of e-bikes. Findings of the study can help us better understand the ILC, and the proposed simulation model is useful for pre-evaluating unimplemented designs for the mixed traffic road segment.
Recently, the demand for comprehension of mixed traffic in developing countries, particularly at roundabouts, which are highly interactive road junctions, has increased. Thus, we analyzed mixed traffic at roundabouts, considering Vietnam as a case study. The two main objectives of this study were to characterize the mixed traffic in Vietnam and to determine the microscopic characteristics of motorcycles at roundabouts. First, efforts were made to clarify the two constitutions of mixed traffic (the performance rule and the presence of small-sized vehicles), and the term “motorcycle-oriented mixed traffic” was defined. Even when satisfying the two fundamental constitutions, this traffic state has unique features, e.g., only one type of non-lane-based vehicle (the motorcycle) and the predominance of motorcycles in the traffic composition (91.7%). Second, four microscopic characteristics of motorcycles were obtained from a large dataset: the motorcycles’ continuous changes in speed, the relationship between the turning angle rate and the speed, the critical gap, and the following space. The relationship between the turning angle rate and the speed was first formulated as a power curve. The critical gap of motorcycles was estimated as a small value (1.25 s) in the case study. The following spaces varied with respect to the speed and had an oval shape. The smallest lateral and longitudinal dimensions were 1.5 and 1.74 m, respectively. While all the findings are meaningful, they are restricted to the case study (Ho Chi Minh City, Vietnam).
This paper develops a novel algorithm for tracking closely-spaced road vehicles using a low-density flash lidar. Low-density flash lidars are recent to the automotive market and have attracted attention due to their low cost. However, these sensors have a poor angular resolution which makes tracking the lateral motion of targets challenging. One such challenge, namely unresolved measurements from multiple vehicles, is addressed in this paper. Detections from multiple targets can become unresolved if the targets are closely spaced. Traditional tracking algorithms, which do not account for unresolved measurements, lead to degraded tracking performance in such scenarios. This paper proposes a novel method based on predicting the lateral motion states of targets forward in time, and truncating their probability density functions at points based on the unresolved measurements. The method proposed works with a computationally simple data association algorithm, requires no sensor modeling, and can track more than two closely spaced targets. The proposed algorithm is evaluated using simulations and on-road experiments, and the results demonstrate its capability in maintaining target tracks even in the presence of unresolved detections. Further, a comparison with the well known Joint Probabilistic Data Association-Merged algorithm showed that the proposed algorithm is computationally lighter.
Based on the interactions among car, bicycle and pedestrian, we in this
paper present a bicycle-following model and a pedestrian-following model
with the consideration of the honk effects. Using the relationship
between the micro and macro variables, we obtain a macro model for
bicycle flow and pedestrian flow. The numerical results show that the
honk effects can enhance the bicycle and pedestrian speeds and flows.
Car-following models NETSIM, INTRAS, FRESIM, and CARSIM have been extensively used for simulation of traffic conditions, including congested conditions. The car-following algorithms of these models are well known and available in the literature. However, the stability, performance, and characteristic car-following behavior of these models have not been investigated in the literature. Since the model outcomes are used in place of real data in most circumstances, it is important to know the individual vehicle behavior and car-following stability of these models. In this paper, the car-following algorithms of the above mentioned models and a recently introduced model, INTELSIM, are examined for their stability and performance in congested traffic conditions. The performance of the car-following models and the individual vehicle behavior are evaluated for accuracy, stability, problem areas, and overall model behavior for the congested conditions. Moreover, this paper aims to help the users utilize the models correctly and understand the outputs better by showing insights to the individual vehicle behavior simulated in the above models. It was found that vehicles in NETSIM and CARSIM models car-follow at separation time headways approximately equal to their reaction times. In addition, INTRAS and FRESIM presented unrealistic acceleration fluctuations and a large number of maximum decelerations. INTELSIM model presented speed and spacing profiles similar to those of the drivers.
The lane change models used in today's traffic simulators often do not determine lane change actions in terms of the evaluation of sequential plans, but rather in terms of the utility of the very next lane change action. This has the disadvantage of not being able to account for the influence of delayed rewards, such as the simulated vehicle moving across a slow lane to a better-performing non-adjacent lane. This research presents a lane change model which at every simulation time step, builds a tree of potential maneuver sequences, and selects the lane change action according to planning over a time horizon. The model was calibrated using a vehicle trajectory data set and shown to give improved realism of lane change actions of individual vehicles, compared to a lane change model without sequential planning.
In this paper, we present a full velocity difference model for a car-following theory based on the previous models in the literature. To our knowledge, the model is an improvement over the previous ones theoretically, because it considers more aspects in car-following process than others. This point is verified by numerical simulation. Then we investigate the property of the model using both analytic and numerical methods, and find that the model can describe the phase transition of traffic flow and estimate the evolution of traffic congestion.
Floating car data of car-following behavior in cities were compared to existing microsimulation models, after their parameters had been calibrated to the experimental data. With these parameter values, additional simulations have been carried out, e.g. of a moving car which approaches a stopped car. It turned out that, in order to manage such kinds of situations without producing accidents, improved traffic models are needed. Good results have been obtained with the proposed generalized force model. Comment: For related work see http://www.theo2.physik.uni-stuttgart.de/helbing.html
There are several commercially available traffic simulation packages that are able to model the full ran e of interchange ramp terminals. Each of these packages has pros and cons for simulating various types of interchanges and traffic control plans. Previous research has Studied specific simulators in terms of their capabilities for simulating single urban point interchanges (SPUIs) and diamond interchanges. There is no guidance provided however on how to generally select appropriate simulators based on their capabilities and internal algorithms for analyzing specific interchange design and control scenarios. This paper focuses on identifying the elements that should be available in a simulator in order to evaluate a specific interchange scenario (including type, geometry, and traffic control characteristics). The paper does not identify all the specific packages that are appropriate for a specific scenario because these evolve constantly: even though the current version of a package may not support a particular function, future versions of that package may incorporate it. Thus, identifying the most appropriate package Would very quickly become obsolete. It is up to the analyst to examine whether a particular characteristic or algorithm is present in a specific package. To accomplish this, three simulators were selected and studied: AIMSUN, CORSIM, and VISSIM. Data from two interchanges (one SPUI and one diamond interchange) at Arizona were obtained and used in the assessment of these packages. The model parameters and assumptions are examined for each model. Simulation is conducted first by using default parameter values followed by a calibration process to adjust parameters related to driver behavior, vehicle performance, and others. In conclusion, several elements are identified as critical in Simulating interchanges, which fall in the following categories: (1) the capability of representation of specific geometric characteristics; (2) the capability of simulating specific signal control plans;. (3) calibration needs and accuracy in comparison to field conditions; (4) the extraction of specific performance measures from the simulator; and (5) other observations from the research.
Advanced traffic management systems (ATMS) and advanced traveler information systems (ATIS) are promising technologies for achieving efficiency in the operation of transportation systems. A simulation-based laboratory environment, MITSIMLab, is presented that is designed for testing and evaluation of dynamic traffic management systems. The core of MITSIMLab is a microscopic traffic simulator (MITSIM) and a traffic management simulator (TMS). MITSIM represents traffic flows in the network, and the TMS represents the traffic management system under evaluation. An important feature of MITSIMLab is its ability to model ATMS or ATIS that generate traffic controls and route guidance based on predicted traffic conditions. A graphical user interface allows visualization of the simulation, including animation of vehicle movements. An ATIS case study with a realistic network is also presented to demonstrate the functionality of MITSIMLab.
In this paper, results of an evaluation of an innovative strategy for minimizing bus bunching are presented. The strategy involves continuous monitoring of bus positions along their route and controlling bus spacing when necessary by employing signal priority and bus holding actions. The evaluation exercise aims to establish traffic and bus operating conditions when the strategy performs best. A simulation model of a hypothetical bus route developed using a PARAMICS (Parallel Microscopic Simulator) is used for this purpose. Bus bunching, measured in terms of disruptions to headways, is found to increase with decreases in design headway, increases in route length, and increases in traffic congestion. When bus spacing is controlled, a significant improvement is seen in cases of shorter design headways of 5 and 10 min, resulting in 80% of cases having more than 10% reduction in excess waiting time and 60% of the cases having more than 20% reduction in excess waiting time.
The behavior of traffic in the heterogeneous environment of an urban uncontrolled intersection is complex and difficult to model. The present study describes the methodology of simulating the traffic flow and thereby estimating the number of conflicts in varying traffic flow conditions. The arrival pattern of vehicles was represented by a multivariate distribution to generate input to the simulation model. The model was validated externally, using field observed data, and was found to predict the number of conflicts well. As an illustration of usefulness of the model, variation of conflict rate (the probability of a vehicle`s getting involved in conflict) due to variation in traffic volume and the proportion of right-turning traffic has been quantified. Under the prevailing traffic composition and turning movements, the conflict rate is estimated to lie in the range of 0.66--0.70, 0.79--0.84, and 0.80-0.87 for intersection volumes of 2,000, 2,500, and 3,000 vehicles per hour, respectively. Issues related to the applicability of the proposed model are briefly discussed.
This paper is an introduction to object-oriented programming (OOP) as it relates to the development of large-scale scientific codes. It is the first of two papers describing OOP issues for scientific-code development. Since object-oriented methods provide for the encapsulation of data and methods, scientific codes can be written in terms of the underlying physics of the problem with less regard for computer-science details. We discuss some of the features of large-scale scientific codes that are amenable to object-oriented design. The concept of efficient portability is elucidated, explaining why object-oriented user codes need not be altered when moving code to radically different computer architectures. In fact, we envision codes running without major changes on serial machines, such as a Sun or Vax; vector machines, such as a Cray; and on massively parallel processor systems, such as the Connection Machine. Comparisons between FORTRAN and the object-oriented programming language of C++ are illustrated with simple examples of matrix operations.
The object-oriented programing (OOP) methodology is introduced as a means for improving the management of a complex engineering software. The drawbacks of existing engineering software development techniques are pinpointed. The basic concepts of the OOP methodology are interpreted in the context of engineering applications. The familiar concept of a matrix is used as an example to interpret the ideas presented. It is concluded that the OOP methodology facilitates the management of complex engineering software systems.
HIPERTRANS (High Performance Transport network modelling and Simulation) is a fast and visually representative simulator that
can predict traffic on a given urban road network. It was designed using object-oriented techniques and by re-engineering
established road traffic models. It has the capability of interfacing to a range of UTC (urban traffic control) systems. Its
high performance version was implemented by using a novel parallel programming platform called SPIDER; it has the capability
of executing faster than real time and runs on distributed processors. The simulator provides a powerful GUI (graphical user
interface) for entering road network models, configuring simulation runs, and visualising simulation results. The system provides
helpful traffic diagnostic tools enabling local transport authorities, policy makers, researchers, and UTC manufacturers to
gainfully exploit its functionality. The HIPERTRANS project was funded by the European Commission under the 4th Framework
programme.
This paper describes a modeling methodology adopted to simulate the flow of heterogeneous traffic with vehicles of wide ranging static and dynamic characteristics. The simulation framework for the traffic-flow model was prepared in such a way that the absence of lane discipline in mixed traffic flow conditions is taken into account. A detailed structure of the proposed model is presented. Common issues related to traffic simulation such as vehicle generation, logics for vehicular movement, etc., are described in detail in the context of heterogeneous traffic conditions. The paper also discusses the procedures adopted for validation of the proposed model and their outcomes. Finally, the details of application of the model to study the traffic flow characteristics on urban roads are also presented. Journal of Transportation Engineering
Because of the tight constraints on many streets in urban areas, it is not uncommon to situate a bus stop upstream of a signal-controlled intersection without the provision of a proper bus bay or setback. For a single-lane approach, where the overtaking of a stopped bus at the bus stop is prohibited, the setup of such a bus stop would significantly affect the delay incurred by road users. It is believed that the delay in such situations depends on a number of factors, such as the distance between bus stop and stop line, traffic and bus flows, dwell time of buses and signal settings. In this paper, a simulation model for estimating the delay on an approach to a signal-controlled intersection with a bus stop upstream is developed. To test the reliability of the model, field surveys were conducted to validate the simulation model. A good agreement between the observed and simulation results was obtained. When the simulation model was used, a new delay formula was established and calibrated for use in the design of a signal-controlled intersection.
This study reports on an in-depth analysis of the properties of Gipps' car-following model. Certain properties of the model are investigated and the need of specific additions to the model is identified. Gipps' car-following model is rather important as it comprises the traffic model of several traffic simulation packages; and the analysis performed in this study determines the actual dynamics that govern model formulae. First, the relationships for the maximum acceleration and deceleration values the model produces are identified. Results indicate that model relationships are such that a vehicle could end up braking harder than its desired deceleration, hence a constraint has to be set. Furthermore, relationships between vehicle acceleration and speed are established. Second, further additions are proposed to allow the model simulate traffic at signal-controlled junctions. These additions include providing a definition for a queueing vehicle and speed manipulation to achieve the calculated saturation flow of simulated junctions.
This paper presents a simulation laboratory for performance evaluation and design refinement of dynamic traffic management systems. The laboratory consists of four integrated components: (1) a traffic management simulator, which mimics the generation of route guidance and operations of traffic signals and signs; (2) a traffic flow simulator, which models individual vehicle movements and drivers` route choice decisions in the presence of real-time traffic information; (3) a surveillance system module, which collects real-time traffic data from sensors and probe vehicles in the simulated network; and (4) a control device module, which implements control strategies and route guidance generated by the traffic management system under evaluation. The simulation laboratory has been implemented in C++ using object-oriented programming and a distributed environment. It features a graphical user interface that allows users to visualize the simulation process, including animation of vehicle movements, state of surveillance sensors, traffic signals, signs, and so on. This modeling system provides a unique tool for evaluating integrated ATIS and ATMS applications in a computer-based laboratory environment.
In this paper, we describe the traffic simulation system which analyzes a traffic flow in a road network. The system is constructed and operated on the parallel computer AP1000. A database of a road network is implemented with the object-oriented programming technique. Elements of a road network are regarded as objects, and vehicles which move on the lanes are regarded as attributive data. The database is divided into sub-databases and assigned to each processor. The system calculates the behavior of vehicles in parallel. Sending and receiving data among the objects are carried out with message passing on the communication network. Moreover, we show the results of the vehicles behavior, and evaluate the parallel efficiency.
SITCUO (Sistemas de Informações de Transportes Coletivos Urbanos por Õnibus) - a dynamic information system for urban bus passengers in Brasilia, using business intelligence, was developed to optimize bus operations and increase the satisfaction of urban transportation users. In order to achieve these objectives the system involves the convergence of a number of different technologies, including: Global Positioning System (GPS), Geographic Information System (GIS), database, data mining, Internet and telecommunications. The system includes communication between the GPS, the database, the Control Centre and the user interfaces, which provide estimated bus arrival times via the information display panels and the Internet. The information system at the Control Centre was implemented by applying Java, JavaServer Pages (JSP), and a Relational Database Management System (RDBMS) using an object-oriented approach. The paper will present the general description of the system, the algorithms for estimating the arrival time of the bus at the bus stop, the implementation procedure adopted, the results of experiments undertaken on a bus route in Brasilia and the conclusions.
The representation of engineering systems in a manner suitable for computer processing is an important aspect of software development for computer aided engineering. The process of abstraction is a well-known technique for developing data representations. Objects are a mechanism for representing data using abstraction, and object-oriented languages are languages for writing programs to manipulate objects. The paper shows through examples the advantages of object-oriented programming for developing engineering software. Mathematical graphs are used as an abstraction for two problems: (1) sorting activities in a schedule and (2) ordering nodes and elements in a finite element mesh. Classes of objects are developed for generic graphs, activity procedence graphs, and graphs of elements meshes. Object-oriented program development leads to modular programs and a substantial reuse of code for the two problems.
This paper develops inhomogeneous cellular automata models to elucidate the interacting movements of cars and motorcycles in mixed traffic contexts. The car and motorcycle are represented by non-identical particle sizes that respectively occupy 6×2 and 2×1 cell units, each of which is 1.25×1.25 meters. Based on the field survey, we establish deterministic cellular automata (CA) rules to govern the particle movements in a two-dimensional space. The instantaneous positions and speeds for all particles are updated in parallel per second accordingly. The deterministic CA models have been validated by another set of field observed data. To account for the deviations of particles’ maximum speeds, we further modify the models with stochastic CA rules. The relationships between flow, cell occupancy (a proxy of density) and speed under different traffic mixtures and road (lane) widths are then elaborated.
Keywords: Car; Inhomogeneous cellular automata; Mixed traffic; Motorcycle
The ability to predict the response of a vehicle in a stream of traffic to the behaviour of its predecessor is important in estimating what effect changes to the driving environment will have on traffic flow. Various proposed to explain this behaviour have different strengths and weaknesses. The paper constructs a new model for the response of the following vehicle based on the assumption that each driver sets limits to his desired braking and acceleration rates. The parameters in the model correspond directly to obvious characteristics of driver behaviour and the paper goes on to show that when realistic values are assigned to the parameters in a simulation, the model reproduces the characteristics of real traffic flow.
Object Oriented Systems Development using Unified Modeling Language Simulation laboratory for evaluating dynamic traffic management systems
- A Bahrami
- Hill
- Singapore
- M E Ben-Akiva
- H N Koutsopoulos
- R G Mishalani
- Q Yang
Bahrami, A. (1999) Object Oriented Systems Development using Unified Modeling Language. Irwin/ McGraw-Hill, Singapore. Ben-Akiva, M.E., Koutsopoulos, H.N., Mishalani, R.G. and Yang, Q. (1997) Simulation laboratory for evaluating dynamic traffic management systems, Journal of Transportation Engineering, ASCE, 123 (4), 283-289.
Studies on mixed traffic flow characteristics under varying composition
- K P Isaac
- A Veeraragavan
Isaac, K.P. and Veeraragavan, A. (1995) Studies on mixed traffic flow characteristics
under varying composition. PhD Thesis, Bangalore University.
A study of linear and lateral placement of vehicles in mixed traffic environment through video-recording
- B N Nagaraj
- K J George
- P K John
Nagaraj, B.N., George, K.J. and John, P.K. (1990) A study of linear and lateral
placement of vehicles in mixed traffic environment through video-recording. Highway
Research Bulletin, Indian Road Congress, 42, 105-136.
Simulation modeling of traffic operations on twolane highways
- V M Kumar
- S K Rao
Kumar, V.M. and Rao, S.K. (1996b) Simulation modeling of traffic operations on twolane highways. Highway Research Bulletin, Indian Road Congress, 54, 211-237.
Simualting bus priority for an urban corridor in Mumbai City Object Oriented Analysis and Design Analysis of urban road traffic through simulation
- J N Bhavsar
- S Sharma
- S L G Dhingra
Bhavsar, J.N., Sharma, S. and Dhingra, S.L. (2007) Simualting bus priority for an urban corridor in Mumbai City. In Proceedings of the 11th World Conference on Transportation Research, University of California, Berkeley, USA. Booch, G. (1994) Object Oriented Analysis and Design. Addison-Wesley, Reading, MA. Chandra, S. and Parida, M. (2004) Analysis of urban road traffic through simulation. Indian Highways, 32, 87-102.
The Unified Modeling Language Reference Manual Modeling conflicts of heterogeneous traffic at urban uncontrolled intersection
- J Rambauch
- I Jacobson
- G Booch
- Addison-Wesley
- Ma Reading
- V T Rao
- V R Rengaraju
Rambauch, J., Jacobson, I. and Booch, G. (1999) The Unified Modeling Language Reference Manual. Addison-Wesley, Reading, MA. Rao, V.T. and Rengaraju, V.R. (1998) Modeling conflicts of heterogeneous traffic at urban uncontrolled intersection. Journal of Transportation Engineering, ASCE, 124 (1), 23-34.
Performance evaluation and design of signal settings
- R Murugesan
- T S Venkataraman
- S K S Moses
Murugesan, R., Venkataraman, T.S. and Moses, S.K.S. (1991) Performance evaluation
and design of signal settings. Indian Highways, 19, 11-19.
A simulation study of delays and queue lengths for uncontrolled T-intersections
- T L Popat
- A K Gupta
- S K Khanna
Popat, T.L., Gupta, A.K. and Khanna, S.K. (1989) A simulation study of delays and
queue lengths for uncontrolled T-intersections. Highway Research Bulletin, Indian
Road Congress, 39, 71-78.
Simulation of intersection flows for mixed traffic
- R K Agarwal
- A K Gupta
- S S Jain
- S K Khanna
Agarwal, R.K., Gupta, A.K., Jain, S.S. and Khanna, S.K. (1994) Simulation of
intersection flows for mixed traffic. Highway Research Bulletin, Indian Road Congress,
51, 85-97.
Simulation of an urban uncontrolled urban intersection with pedestrian crossings
- S K M Raghavachari
- K M Badrinath
- M P R Bhanu
Raghavachari, S.K.M., Badrinath, K.M. and Bhanu, M.P.R. (1993) Simulation of an
urban uncontrolled urban intersection with pedestrian crossings. Highway Research
Bulletin, Indian Road Congress, 48, 29-49.
Object Oriented Systems Development using Unified Modeling Language
- A Bahrami
Bahrami, A. (1999) Object Oriented Systems Development using Unified Modeling
Language. Irwin/ McGraw-Hill, Singapore.
Analysis of urban road traffic through simulation
- G Booch
- Addison-Wesley
- M A Reading
- S Chandra
- M Parida
Booch, G. (1994) Object Oriented Analysis and Design. Addison-Wesley, Reading, MA.
Chandra, S. and Parida, M. (2004) Analysis of urban road traffic through simulation.
Indian Highways, 32, 87-102.
Simualting bus priority for an urban corridor in Mumbai City
- J N Bhavsar
- S Sharma
- S L Dhingra
Bhavsar, J.N., Sharma, S. and Dhingra, S.L. (2007) Simualting bus priority for an urban
corridor in Mumbai City. In Proceedings of the 11th World Conference on
Transportation Research, University of California, Berkeley, USA.