Matthew G. Karlaftis

National Technical University of Athens | NTUA · School of Civil Engineering

CERN, καθώς επίσης αξιολογεί ενδεχόμενες λύσεις για τη δημιουργία ενός βιώσιμου συστήματος μεταφορών για την κοινότητα του CERN. Για να αναλυθούν οι συνήθειες μετακίνησης και η ικανοποίηση των μελών της κοινότητας του CERN, αναπτύχθηκαν μοντέλα δηλωμένων και αποκαλυπτόμενων προτιμήσεων. Στη συνέχεια, δομήθηκαν και αξιολογήθηκαν διαφορετικές πολιτικ...

With environmental concerns on the rise, identifying the factors that affect travel demand for energy efficient and environmentally friendly means of transportation becomes critical. It is, thus, beneficial to identify the characteristics of new energy type – low CO2 emissions – transport habits. Travel time is one such characteristic that has been...

The successful introduction of LRT systems is inevitably related to the realistic estimation of their ridership; this is particularly true for cases of no prior experience in the use of such modes in the part of the traveling public. This paper presents a practical approach for developing a direct demand model, for the case of a planned LRT system...

Performance evaluation of transit system elements is a required process for decision makers willing to redesign its structure, operations, and services. In this paper, we employ Data Envelopment Analysis and neural network regression to investigate the efficiency of bus depots and lines for the Athens (Greece) bus system. Results reveal differences...

This paper investigates the effects of economic recession on congestion pricing acceptability. We use data from two questionnaires; one before (2008) and one during (2013) the financial recession periods. The results show statistically significant differences in the responses to the two questionnaires regarding acceptability of the pricing system,...

Renewable energy technologies are developing rapidly, while in the last decade great interest is encountered in the use of wind energy, especially due to the energy crisis and serious environmental problems appeared from the use of fossil fuels and therefore a large number of wind farms have been installed around the world. On the other hand the ab...

We investigate the factors that affect passenger decisions regarding airline choice. Three Multivariate Probit (MP) models are developed to analyze data for a sample of 853 respondents. This methodology allows for modeling the simultaneous, yet separate, consideration of airline choice determinants. Fare, safety and reliability, and friendly-and-he...

This paper investigates the impact of the economic recession on the taxi market in Greece. Data are used from two questionnaires, addressed to both taxi drivers and users. The perceptions of drivers and users about the effects of recession, service quality issues, and possible solutions to mitigate the negative impacts are recorded. The statistical...

Seaplanes offer a time and cost-efficient service for supporting transportation needs in island chains. This paper investigates the design of a seaplane network connecting the Greek islands with the mainland, a service currently accommodated by ferries. Design of seaplane routes is modeled as a multi-objective capacitated vehicle routing problem wi...

The applicability of the theory of Recurrence Plots and Recurrence Quantification Analysis to short-term traffic flow is demonstrated through three distinct road traffic case studies. The first focuses on short-term traffic patterns of volume and speed in urban freeway sections. The second case study examines urban traffic flow dynamics under diffe...

Abstract We develop a life-cycle cost model for assessing wind parks; implementing the model requires calculation of cost components that are related to wind tower structural performance for multiple wind hazard levels. We compute the structural capacity of the wind towers by means of nonlinear static structural analysis for three wind hazard level...

Major highway infrastructure elements, in need of post-earthquake maintenance for improved highway life-cycle, motorist’s guidance, and safety, include bridges, pavements, interchanges, and tunnels. In addition, there are numerous, minor infrastructure elements vital to motorist’s guidance and safety, such as overhead and roadside appurtenances, in...

A methodological framework for multiple steps ahead parking availability prediction is presented. Two different types of predictions are provided: i. the probability a free space to continue being free in subsequent time intervals, and ii. the short-term parking occupancy prediction in selected regions of an urban road network. The available data c...

Weather conditions have a strong effect on the operation of vessels and unavoidably influence total time at sea and associated transportation costs. The velocity and direction of the wind in particular may considerably affect travel speed of vessels and therefore the reliability of scheduled maritime services. This paper considers weather effects i...

This is the second part of a two-part survey investigating transportation network post-disaster planning and management. The first part focused on efforts and models for the estimation and assessment of post-disaster network performance (PDNP). This paper addresses the problem of decision-making and planning of post-disaster network operations (Pos...

In recent years, disasters have an increasing impact on modern societies in terms of both economic and human losses. Following disasters, transportation networks act as key lifelines enabling access to the affected communities and supporting evacuation, emergency response, relief and recovery operations. In this context, this two-part survey offers...

Vital lifelines in the event of a disaster, transportation networks support evacuation activities, emergency logistics, and the restoration of daily activities. The rapid recovery of surviving transportation network operations immediately after a disaster is critical for the well-being of communities. The focus here is on planning highway operation...

We investigate demand in a multimodal public transportation context for the city of Athens. Demand is expressed as a function of operational and macroeconomic factors and is analyzed using a time-series cointegration and error correction approach. This allows for treating non-stationary data, for determining short and long term elasticities and at...

Urban regeneration projects in modern metropolitan areas often incorporate major changes in the structure and operations of a city’s transportation system. In this paper we discuss traffic impacts of such a project, the pedestrianization of a major arterial, in the Athens, Greece downtown area, by applying an ex-ante evaluation of the project on a...

This chapter presents a Data Envelopment Analysis (DEA) protocol for analyzing the efficiency of metropolitan transit agencies that oversee multiple types of transportation services. The protocol is illustrated by applying it to United States transit agencies that can serve their cities with four types of subunits: self-operated motorbus, outsource...

In this paper we study driver behaviour changes when driving vehicles equipped with Intelligent Speed Adaptation (ISA) systems. The primary tool used is a driving simulator. Three different ISA human machine interface functionalities are investigated: informative, warning, and intervening. Data were extracted from the simulator along with questionn...

Rapid and efficient implementation of demolition along invasion routes is critical for ground defence operations. The related process includes a series of interrelated actions that have to be carefully planned in order to successfully complete demolition operations; units have to estimate and allocate human and material resources and establish appr...

We analyze market shares for each public transport mode in total public transport ridership for the multimodal public transportation system of Athens, Greece. This analysis provides useful information for making investment decisions concerning the public transport infrastructure and for allocating subsidies. Due to the non-stationary properties of...

We examine the effects of incident occurrence on freeway traffic. Although the true influence of a freeway incident may not be directly observed, it may be identified using the maximum spatial extent of the disturbance induced to upstream traffic. Spatial and temporal extent is susceptible to various traffic, weather, geometry and incident specific...

Univariate and multivariate neural network (NN) and autoregressive time series models are compared with regard to application to the short-term forecasting of freeway speeds. Statistical tests are used to evaluate the developed models with respect to temporal data resolution, prediction accuracy, and quality of fit. The results indicate that, by an...

Transit systems should provide attractive yet low cost services to passengers. However, reduction of operating costs can significantly affect performance of bus systems. Cutbacks in deadhead mileage and depot costs becomes attractive since it leads to reducing operating expenses without interfering with passenger services. We revisit previous work...

Service quality, performance, and attractiveness of transit systems are related to the condition of their infrastructures; it is therefore desirable for transit infrastructures to be in the best possible condition and offer an attractive, safe, and friendly environment for travelers. This paper presents a model for rating the condition and performa...

An approach for predicting incident durations that are susceptible to severe congestion, the occurrence of secondary incidents, and their joint effect is proposed. First, a fuzzy entropy feature selection methodology is applied to determine redundant factors and rank factor importance with respect to their contribution on the predictability of inci...

Security of transportation infrastructure is of primary importance in recent years as a result of various breaches worldwide. Increased security concerns lead transportation authorities to improve, upgrade, and enhance surveillance, prevention, and response equipment in facilities, frequently under tight budgetary and operational constraints. In th...

This paper extends research on miscommunication between air traffic controllers and pilots by developing statistical models that predict the outcome of communications within the scope of controller-pilot data communications in the Next Generation Air Transportation environment. A database of controller-pilot voice messages from high and super-high...

Young individuals who drive under the influence of alcohol have a higher relative risk of crash involvement; as such, the literature has extensively investigated the factors affecting such involvement through both post-accident surveys and simulator experiments. The effects of differentiated breath alcohol concentrations (BrAC) on young driver beha...

An approach for predicting incident durations that are susceptible to severe congestion, the occurrence of secondary incidents, and their joint effect is proposed. First, a fuzzy entropy feature selection methodology is applied to determine redundant factors and rank factor importance with respect to their contribution on the predictability of inci...

The likelihood of the occurrence of secondary incidents is usually linked to primary incidents by using predefined spatial and temporal criteria. This paper extends past research on secondary incident detection by defining the dynamic thresholds of the influence area of a primary incident, using detailed freeway traffic data from upstream loop dete...

Current research on secondary crash identification links the likelihood of secondary crashes occurrence to primary incidents using pre-defined spatial and temporal criteria. This paper extends past research on secondary crash detection by defining dynamic thresholds of the influence area of a primary incident using detailed real-time collected free...

Traffic data aggregation has been a serious factor of inaccuracy in most road safety studies. The Average Annual Daily Traffic (AADT) has been the most commonly used measure to reflect traffic conditions. In this paper, we establish a framework for the integration of real-time traffic data in road safety analysis. To this end, we explore the effect...

The past few years have seen a significant increase in low-cost carrier traffic that has in several ways, affected airport operations. Only limited analysis, however, of the connection between airport efficiency and low-cost carriers has been conducted. We use data from 10 Greek airports that handle approximately 85% of low-cost carrier demand in t...

Young people who drink and drive have a relatively higher risk of crash involvement for all breath alcohol concentration (BrAC) ranges. However, not all aspects of the effect of alcohol consumption on the behavior of young drivers have been sufficiently addressed especially the differentiated effect of alcohol on their driving performance. The beha...

This paper investigates the factors that affect household automobile and motorcycle ownership in large metropolitan areas. Extensive geocoded trip data from Athens, Greece, were modeled with the random parameters bivariate ordered probit model. This model accounts for unobserved heterogeneity in the data population and commonly shared characteristi...

The traditional approach to the analysis of urban travel includes a detailed and complex modeling system that considers activity and trip generation (including time-of-day of trip) and destination, mode, and route choices. Although the insights that one can gain from such a comprehensive approach are undeniable, a more simplistic approach that focu...

Maintaining, restoring, and improving urban infrastructure has been recognized as one of the engineering grand challenges of the 21st century by the National Academy of Engineering. The challenges arise from both the design and the construction of such infrastructure. Designing a new highway is a very complex problem that should combine data from v...

Adverse weather conditions may have a significant impact on the statistical characteristics of traffic variables such as volume and speed, and consequently on their predictability. We address the problem of freeway lane speed variability under the effect of precipitation episodes and present a non-linear dynamics methodology based on recurrence qua...

To extract useful information on variables that are associated with secondary accident likelihood this paper develops neural network models with enhanced explanatory power. Traffic and weather conditions at the occurrence of a primary incident are explicitly considered. Two measures to extract variable significance are introduced: mutual informatio...

This paper describes a statistical method for estimating data envelopment analysis (DEA) score confidence intervals for individual organizations or other entities. This method applies statistical panel data analysis, which provides proven and powerful methodologies for diagnostic testing and for estimation of confidence intervals. DEA scores are te...

This paper focuses on identifying important factors that determine activity-based travel distance in urban areas. Building on past research that has demonstrated the conceptual equivalence of hazard models applied to either temporal or spatial settings, the length of the distance from origin to destination is statistically modeled as longitudinal d...

In an era of continuous growth in mobility and demand for transportation, safety is an issue of major social concern and an area of extensive research and work by practitioners and academics. Emergency response services are very important in handling and minimizing the impacts of traffic accidents and for saving human lives. In this paper, we devel...

The need to measure transit system performance along with its various dimensions such as efficiency and effectiveness has led to the development of a wide array of approaches and vast literature. However, depending upon the specific approach used to examine performance, different conclusions are oftentimes reached. Using data from 15 European trans...

This study uses aggregate state-level data from 1999 to 2006 in the United States to examine the relationships among pavement performance (pavement roughness) and preservation expenditure, dominant surface geology, and climate. To account for possible random variations in parameters across geographic locations and time periods, a random-parameters...

Although weather, traffic mix and speed variability across lanes are largely considered as significant determinants of traffic flow characteristics on freeways, they have not been incorporated into short-term traffic forecasting models. We evaluate the effects of weather and traffic mix on the predictability of traffic speed using several vector au...

Bus lanes have been widely implemented internationally for improving the performance and quality-of service of surface transit systems. Despite their importance to a city’s transit system, bus lanes are frequently violated by road users resulting in subpar service standards. Using extensive field data measurements from Athens, Greece, we analyze vi...

Export Date: 8 January 2013, Source: Scopus

Taxis are a very important mode of transport particularly in larger urban areas. Despite the significant research that has gone into this mode, the literature has not investigated taxi travel time, a characteristic of importance particularly for pricing, traffic, and transport mode choice studies. We use data from an extensive revealed preference (...

Traffic hysteresis is a characteristic of congested traffic and may have significant implications on freeway traffic operations. We analyze hysteresis through vehicle trajectories on both a macroscopic and a microscopic level. Instances of traffic hysteresis are detected and categorized. Then, their macroscopic and microscopic traffic flow characte...

Research on all aspects of road safety for older drivers is becoming increasingly important as a result of both higher population age and increased crash exposure for older drivers. In this paper we investigate two important, yet largely under-researched issues regarding older drivers; first, we examine perceptions regarding road safety issues and,...

Public transportation in a metropolitan area often is supplied by multiple types of transit. This paper develops and illustrates a DEA-based procedure for estimating: overall efficiency of an area’s public transportation; technical efficiencies of the individual transit types; effect of each type on overall efficiency; and efficiency of the allocat...

This paper extends prior research on miscommunication between air traffic controllers and pilots by developing statistical models to predict the outcome of communications within the scope of Controller Pilot Data Link Communications (CPDLC) in the Next Generation Air Transportation (NextGen) environment. A database of 7,965 controller-pilot voice m...

Search and rescue operations following natural disasters have become the cornerstone for minimizing the adverse social effects and the impact of these hazards. Despite their importance, the literature has not adequately dealt with post disaster operations–at least in part–because of the difficulty in rapidly solving the mathematically complex probl...

Waiting time in bus stops heavily affects traveler attitude towards public transportation and therefore is an important element for consideration when planning and operating a bus system. Furthermore, what passengers perceive as waiting time is often quite different from their actual waiting time at a bus stop. In this context, we present an empiri...

The need for dependable and flexible models of transit vehicle maintenance has been well established in the literature as a means for improving daily operations, capital planning and service quality. Stemming from the practical need to predict the duration of maintenance activities and active service time for buses, this paper uses the principles o...

In the field of transportation, data analysis is probably the most important and widely used research tool available. In the data analysis universe, there are two ‘schools of thought’; the first uses statistics as the tool of choice, while the second – one of the many methods from – Computational Intelligence. Although the goal of both approaches i...

Emergency response services are critical for modern societies. This paper presents a model and a heuristic solution for the optimal deployment of many emergency response units in an urban transportation network and an application for transit mobile repair units (TMRU) in the city of Athens, Greece. The model considers the stochastic nature of such...

Motorcycles are a widespread mode of travel in several parts of the world as, for example, in Southern Europe and Asia. However, motorcycle ownership and usage have been scarcely examined, despite being critical for developing transportation and traffic safety plans and policies in urban areas with high motorcycle presence. This pap dels are develo...

This paper studies public transport demand by estimating a system of equations for multimodal transit systems where different modes may act competitively or cooperatively. Using data from Athens, Greece, we explicitly correct for higher-order serial correlation in the error terms and investigate two, largely overlooked, questions in the transit lit...

We examine the effects of various traffic parameters on type of road crash. Multivariate probit models are specified on 4-years of data from the A4-A86 highway section in the Ile-de-France region, France. Empirical findings indicate that crash type can almost exclusively be defined by the prevailing traffic conditions shortly before its occurrence....

The considerable impact of congestion on transportation networks is reflected by the vast amount of research papers dedicated to congestion identification, modeling, and alleviation. Despite this, the statistical characteristics of congestion, and particularly of its duration, have not been systematically studied, regardless of the fact that they c...

Cited By (since 1996): 1, Export Date: 8 January 2013, Source: Scopus

Cited By (since 2011): 1

Time series techniques are useful for analyzing transportation data, uncovering past trends and providing projections. Such analyses are sensitive to the temporal aggregation of the data, an issue that has been widely ignored in the transportation literature. In traffic engineering, aggregation usually equals to the average of a variable across lar...

Incidents are a major source of uncertainty in freeway operations. Secondary crashes are an important category of freeway incidents. Until now, secondary crashes have been assumed to occur at the boundary of high-density queues formed upstream of an initial crash. While much research has concentrated on the relationship between incident duration an...

Current advances in artificial intelligence are providing new opportunities for utilizing the enormous amount of data available in contemporary urban road surveillance systems. Several approaches, methodologies, and techniques have been presented for analyzing and forecasting traffic counts because such information has been identified as vital for...