Kai Liu

Kai Liu
Dalian University of Technology | DUT · School of Transportation and Logistics

Professor
Transportation Research Part D: Call for papers on Special Issue: Electrification pathways for public transport systems

About

62
Publications
15,181
Reads
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948
Citations
Introduction
Modeling demands and adoption behavior of electric vehicles under uncertain environment and their impact on transportation systems; Impacts of Innovation services on EV charging network based on mobile internet technology; Intersection Cooperative Adaptive Speed Guidance System Design for Vehicle Energy Saving and Traffic Emission Reduction;
Additional affiliations
March 2009 - present
Dalian University of Technology
Position
  • Professor (Associate)
January 2007 - March 2009
Kobe University
Position
  • Research Associate
January 2007 - March 2009
Kobe University
Position
  • COE Researcher

Publications

Publications (62)
Article
Full-text available
Citation: Gao, H.; Li, A.; Wang, J.; Liu, K.; Zhang, L. Design of an Intelligent Platoon Transit System towards Transportation Electrification. World Electr. Veh. J. 2022, 13, 153. https://doi.org/10.3390/wevj13080153
Article
Full-text available
The problem of learning from imbalanced ride-hailing demand data with spatiotemporal heterogeneity and highly skewed demand distributions is a relatively new challenge. Current prediction methods usually filter out some spatiotemporal partitions with sparse demands by setting a minimum ride-hailing demand threshold, where the dataset is always assu...
Preprint
Full-text available
The high failure rate of demand-responsive transit (DRT) systems demonstrates that DRT services are viable only in selected human settlements. However, few studies have quantitatively examined how built environment characteristics affect DRT use. Applying gradient boosting decision trees to the data of customized bus service (CBS, a type of DRT) in...
Article
Electric vehicles (EVs) are the most important components of smart transportation systems. Limited driving range, prolonged charging times, and inadequate charging infrastructure are the key barriers to EV adoption. To address the problem of prolonged charging time, the simple approach of developing a new charging station to enhance the charging ca...
Article
Full-text available
The premise of the large-scale operation of electric buses corresponds to efficient charging service guarantees. Recent research on charging stations mainly aims to obtain the construction location and construction sequence through optimization methods or decision-making methods. This research has considered the aspects of geography, charging effic...
Article
Full-text available
The accurate short-term travel demand predictions of ride-hailing orders can promote the optimal dispatching of vehicles in space and time, which is the crucial issue to achieve sustainable development of such dynamic demand-responsive service. The sparse demands are always ignored in the previous models, and the uncertainties in the spatiotemporal...
Article
Understanding the mechanism of continuous subscribing behavior is vital to the operation and even survival of customized bus (CB) systems. Capturing the differences in subscribing behavior of active and inactive users and developing targeted and differentiated marketing strategies accordingly will help to improve the user retention rate. The result...
Preprint
Full-text available
Dynamic demand prediction is a key issue in ride-hailing dispatching. Many methods have been developed to improve the demand prediction accuracy of an increase in demand-responsive, ride-hailing transport services. However, the uncertainties in predicting ride-hailing demands due to multiscale spatiotemporal granularity, as well as the resulting st...
Article
Full-text available
Charging management has a profound impact on the reliability and safety of electric bus (EB) services. However, the actual charging operation of EB fleets is a critical challenge due to uncertain energy consumption, limited charging resources and other factors. A deterministic model and a robust model with a probability-free uncertainty set are pro...
Article
The rapid growth of transportation sector and related emissions are attracting the attention of policymakers to ensure environmental sustainability. Therefore, the deriving factors of transport emissions are extremely important to comprehend. The role of electric vehicles is imperative amid rising transport emissions. Electric vehicles pave the way...
Article
Full-text available
The large-scale application of electric buses highlights a series of practical problems, such as high charging costs, unreasonable utilization of charging resources, and chaotic charging schedules. In this study, a mixed integer programming model was first proposed to reduce the total charging cost of electric bus fleets by optimizing the charging...
Article
In this paper, we present an ensemble stacked generalization (ESG) approach for better prediction of electric vehicles (EVs) energy consumption. ESG is a weighted combination of multiple base regression models to one meta-regressor, which enhances the model prediction and decreases the model variance over a single regressor model. For the current s...
Article
This paper proposes customized bus (CB) demand models to investigate dynamic adjustments, spatial dependence, and spatial spillover effects using spatial dynamic panel data techniques and a balanced panel data set collected over two years. The endogeneity introduced by spatial dependence effects is resolved by extending the moment restrictions of t...
Article
The users' taste preferences for the demand responsive customized bus (DRCB) and, in particular, the its mechanism of hetero-geneity, which determine routing, timetabling, and even launch and cancellation of the DRCB service, have not been given enough attention. Using a stated preference experiment in the context of mode choice between DRCB and a...
Article
Customized bus services, as a new variant of dial-a-ride services, are an attempt to provide demand-oriented bus services to commuters who submit their requests to designated information platforms. This study proposes an interesting customized bus service design problem by considering travel demand uncertainty. Given a fleet of heterogeneous vehicl...
Article
Full-text available
With the rapid development of electric vehicles (EVs), one of the urgent issues is how to deploy limited charging facilities to provide services for as many EVs as possible. This paper proposes a bilevel model to depict the interaction between traffic flow distribution and the location of charging stations (CSs) in the EVs and gasoline vehicles (GV...
Preprint
Long-term passenger subscription is vital to the survival and operation of the customized bus (CB) system, which is a demand-driven and user-oriented transit service. A better understanding of passenger loyalty toward the CB service will help provide better operation. The urgent and outstanding issue is how to incorporate the unobserved heterogenei...
Article
Full-text available
Although electric vehicles (EVs) have been regarded as promising to reduce tailpipe emissions and energy consumption, a mixed traffic flow of EVs and internal combustion engine vehicles (ICEVs) makes the energy/emissions reduction objective more difficult because EVs and ICEVs have various general characteristics. This paper proposes a low-emission...
Article
Full-text available
After attaining great prevalence from the end of 2013, customized bus (CB) transit services have experienced a huge decline in China. The feasibility of this new bus sharing system is thus being questioned. Therefore, it is imperative to investigate the actual role of CB services in the overall transportation system based on successful cases, as th...
Article
Full-text available
After attaining great prevalence from the end of 2013, customized bus (CB) transit services have experienced a huge decline in China. The feasibility of this new bus sharing system is thus being questioned. Therefore, it is imperative to investigate the actual role of CB services in the overall transportation system based on successful cases, as th...
Article
Full-text available
During the last ten years, with the pervasive applications of information technologies, emerging transportation-related 'big data' has provided opportunities to strengthen the understanding of transportation systems and their geo-spatial impacts. This big data has been generated from both onboard and roadside equipment, such as mobile phones, GPS d...
Article
Full-text available
In recent years, car sharing has emerged as a novel alternative to private car ownership in urban areas worldwide. Potential benefits of this system include improved mobility and reduced congestion, vehicle ownership, parking issues, and greenhouse gas (GHG) emissions. This study aimed to investigate travelers’ acceptance of car sharing systems thr...
Article
Full-text available
We proposed a new crash surrogate metric, i.e., the maximum disturbance that a car following scenario can accommodate, to represent potential crash risks with a simple closed form. The metric is developed in consideration of traffic flow dynamics. Then, we compared its performance in predicting the rear-end crash risks for motorway on-ramps with ot...
Article
Full-text available
There still exists large amounts of challenges by applying the cooperative vehicle-to-infrastructure (V2I) proactive safety solutions into traffic management and control practice, since drivers may have huge differences in perception, judgment and operation. In order to provide better understanding of the warning effectiveness of cooperative V2I cr...
Article
The adoption of a vehicle-to-infrastructure (V2I) cooperative crossing collision prevention system (CCPS) has been recognized as an option for reducing accident risk at intersections. However, the effects of driver characteristics on the general design of CCPSs have remained relatively un-examined. This study was conducted based on a field operatio...
Article
The ability to accurately predict the energy consumption of electric vehicles (EVs) is important for alleviating the range anxiety of drivers and is a critical foundation for the spatial planning, operation and management of charging infrastructures. Based on the GPS observations of 68. EVs in Aichi Prefecture, Japan, an energy consumption model is...
Article
Full-text available
The ability to accurately predict the energy consumption of electric vehicles (EVs) is important for alleviating the range anxiety of drivers and is a critical foundation for the spatial planning, operation and management of charging infrastructures. Based on sparse GPS observations of 68 EVs in Aichi Prefecture, Japan, an energy consumption model...
Article
This paper aims to investigate the choice for charging mode and location with the revealed preference data of battery electric vehicle (BEV) users in Japan. Three alternatives including the normal charging at home (for private BEVs)/company premise (for commercial BEVs), normal charging at public charging stations and fast charging at public chargi...
Article
Full-text available
Improving the estimation accuracy for the energy consumption of electric vehicles (EVs) would greatly contribute to alleviating the range anxiety of drivers and serve as a critical basis for the planning, operation, and management of charging infrastructures. To address the challenges in energy consumption estimation encountered due to sparse Globa...
Article
In this paper, we propose a speed guidance model to explore the influences of the drivers’ bounded rationality on the vehicle’s fuel consumption and emissions during the whole process of the vehicle passing through the signalized intersection. In the proposed speed guidance model, we apply three parameters (i.e., the response time, acceptance thres...
Article
In this paper, we apply the FVD (full velocity difference) model to study the influences of MVFS (mean velocity feedback strategy) and NVFS (the number of vehicles feedback strategy) on each vehicle’s running cost and each route’s total cost in a two-route system from the numerical perspective. The numerical results illustrate that MFVS and NVFS ha...
Article
Full-text available
On urban arterials, travel time estimation is challenging especially from various data sources. Typically, fusing loop detector data and probe vehicle data to estimate travel time is a troublesome issue while considering the data issue of uncertain, imprecise and even conflicting. In this paper, we propose an improved data fusing methodology for li...
Data
Vehicle Record from Day 1 to Day 4. (RAR)
Article
We analyze whether proximity effect, preferential attachment and path dependence or three “P” mechanisms would concur within the evolutionary process of inter-regional network. Using a unique database of China’s technology transaction between regions, we show that proximity effect, preferential attachment and path dependence have coexisted in the e...
Article
The driver’s bounded rationality has significant influences on the micro driving behavior and researchers proposed some traffic flow models with the driver’s bounded rationality. However, little effort has been made to explore the effects of the driver’s bounded rationality on the trip cost. In this paper, we use our recently proposed car-following...
Article
Full-text available
As the parcel delivery service is booming in China, the competition among express companies intensifies. This paper employed multinomial logit model (MNL) and latent class model (LCM) to investigate customers’ express service choice behavior, using data from a SP survey. The attributes and attribute levels that matter most to express customers are...
Conference Paper
Full-text available
A survey with 3 cases was carried out in order to describe travelers’ route choice behavior more precisely with cumulative prospect theory (CPT). The expression of the probability weighting function for the route choice problem was discussed and identified based on a sample group, which was obtained through non-linear regression. A parameter system...
Article
Full-text available
Electric vehicles (EVs) will certainly play an important role in addressing the energy and environmental challenges at current situation. However, location problem of EV charging stations was realized as one of the key issues of EVs launching strategy. While for the case of locating EV charging stations, more influence factors and constraints need...
Conference Paper
Toyota City, the Environment Model City selected by the Central Government of Japan, moves forward as a smart city by instigating a countermeasure of promoting Plug-in Hybrid Electric Vehicles (PHEV or PHV). Thus, subsidy of the city government is added to that of the central government for buying PHV and/or EV. In 2009 the city government built 11...
Conference Paper
The installation site of loop detectors directly influences the quantity and quality of information detected and processed. Searching appropriate installation sites not only contributes to realizing more accurate traffic estimation, but also is able to accomplish a better cost-effectiveness. In this paper, three positions were chosen as the loop lo...
Conference Paper
In this paper, we propose an optimal toll-points road pricing strategy based on the artificial bee colony (ABC) method for the second-best road pricing problem. Then a comparison is made between optimal toll-points road pricing strategy and cordon pricing schemes. It shows that the ABC algorithm can solve the road pricing problem well and a compari...
Conference Paper
The paper proposes a simulation-based approach to determine the small sample size of probe vehicles with consideration of road network coverage and link average speed estimation. The simulation is designed to analyze the change of the elasticities of network coverage and estimation accuracy with sample size below 5, using random sampling and regres...
Conference Paper
Full-text available
This article addressed the willingness to pay for renting low speed private transportation mode (LSPTM) within the downtown areas of large cities. The influence factors of shared-use LSPTM system are investigated through a well designed internet-based stated preference survey. The embedded Google map and Ajax model improve the performance of web SP...
Conference Paper
Full-text available
An internet stated preference (SP) survey was developed in order to investigate an operational strategy in practice for a new kind of personal travel assistance mode - Low Speed Private Transportation Mode (LSPTM) system. This article outlines the idea and methodology of developing an SP survey which applies the recent innovations of Google-map API...
Article
Full-text available
Using commercial vehicle fleets as probes may be a cost-effective method for obtaining real-time traffic information. Because the taxi dispatch system automatically records the location of a taxi traveling in an urban network, large quantities of real-time travel data can be obtained at low cost. The reliability of this information about real-time...
Conference Paper
Probe vehicles are playing an increasingly important role in the field of ITS, and showing high value for various applications over the last decade. Recent advances of probe vehicle technologies in Japan are explored by reviewing the existing studies in both academic fields and ITS practice projects. The methods of data collection and data processi...
Article
Full-text available
One serious problem of continuous large-scale data collection with probe vehicle is the dilemma of balancing the cost economization and system reliability improvements. The polling frequency is found to be one of the major factors that determine the operation cost of a probe vehicle-based traffic data collection system. This paper focuses on evalua...
Article
Full-text available
The development of traffic data collection is promoted by IT technology. Probe vehicles are playing an increasingly important role in the field of ITS, and showing high ability for various ITS applications in the last decade. The overwhelming superiority of probe technology relies on a good coverage and a high penetration rate of probe vehicles. Al...
Article
Full-text available
Delay times at intersections are one of the most important types of information for ATIS (advanced traveler information systems). Even though probe vehicles have already been used to directly measure delay times, the ongoing collection of real-time delay information on a large scale depends on reducing transmission costs to a reasonable level. Redu...
Article
Full-text available
Accurate link travel time estimations obtained using probe vehicles are crucial to reliable dynamic route guidance systems. This study attempts to understand what level of travel time estimation reliability can be achieved from a given frequency of probe data. Hence the focus is on the variability of link/roadway segment travel time estimates for d...
Article
Full-text available
Two types of probe-vehicle polling scheme, using time-based probe intervals and space-based probe intervals, are investigated in this paper in order to provide more insight into their cost-effectiveness in real-time traffic data collection. The basic characteristics of the two schemes are examined and compared using simulated data at lower polling...

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Projects (8)
Project
https://www.journals.elsevier.com/transportation-research-part-d-transport-and-environment/call-for-papers/call-for-papers-on-special-issue-electrification-pathways-for-public-transport-systems Given the need to reduce greenhouse gas emissions worldwide, public transport electrification will also need to occur as many governments are now setting targets for implementation within the next decade. Challenges remain with current technology, including the constraints imposed by hot or cold weather on battery lifetimes, the restructuring of networks to account for range limitations, and the need to train both planning and maintenance staff in how to address these challenges. This Special Issue seeks high-quality research in the implementation of electrified public transport systems. In particular, we invite studies on the development and implementation of theories and planning practices in order to gather insights on the possible pathways for electrified public transport.
Project
This Special Issue is devoted to emerging technologies of transportation planning and management during the electrification process of urban mobility. This Special Issue intends to encourage scholars and experts to systematically discuss the possible ways to accelerate the electrification of urban mobility and discuss the effects/mechanisms of related endogenous and exogenous factors in the transportation system and finally to provide potential policy references for urban transportation planning and management during the electrification process. Prospective authors are invited to submit original contributions that include, but are not limited to, the following topics of interest: Emerging challenges in the transition of transportation electrification. Intelligent vehicle-to-grid system. Policy incentives in terms of penetration of electric vehicle in the private and public transportation market. Advanced energy management system of road network. Intelligent operation and maintenance system of infrastructure. Exploration of new service patterns in the transition phase of electrification. Agent-based simulation system. Intelligent information system that addresses extreme driving range anxiety. Incentive strategies that help shape ‘healthy’ driving and charging habit. Energy consumption efficiency measurement and improvement. Operation optimization for transit electrification. Eco-routing model.