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In order to obtain an effective method for solving route travel time reliability, this paper proposes an effective new method to calculate travel time reliability using an independent link travel time function. Based on several months of historical data, the results show that the Edgeworth expansion can better reflect travel time distribution law. In addition, travel time reliability can be calculated more conveniently by combining an approximate discretization algorithm and an empirical distribution function.

With the development of technology, connected and autonomous vehicles (CAVs) have great potential in the future transportation systems. It provides a new way for expressway operation and management, and has become one of the important technique measures of the development of Intelligent Transportation System (ITS). Travel time plays a greatly important role in the research and development of the Intelligent Transportation Systems. In our study, SUMO (Simulation of Urban Mobility), as the simulation platform, is used to build traffic simulation scenarios under various traffic volumes and various penetration rates, then, the mapping relationship between various penetration rates and traffic state under various traffic volumes is established, and finally, the travel time function under various traffic volumes and penetration rates is established based on the soft set. The result clearly shows that the MAPE of our method is 0.066286 and the RMSE of our method is 13.88986, and the scenario with high penetration rates has smaller MAPE and RMSE than other penetration scenarios.

This study aims to examine the impact of traffic incidents occurring on general purpose lanes (GPLs) on the travel time reliability of high-occupancy vehicle (HOV) lanes on freeways and to evaluate the differences of travel time reliability on GPLs and HOV lanes under the same incident conditions. In this paper, an empirical travel time reliability analysis is conducted using the travel time and incident data collected between 2009 and 2012 on Interstate 5 and Interstate 405 of the Seattle metropolitan area. Three incident types (i.e., shoulder incident, single lane incident, and multiple lane incident) are considered. Two measures, percentile-based indicator and inflow–percentile travel time function, are used. The results suggest that incidents result in lower values of travel time reliability for all the measures. The results also show that multiple lane incident type has the most significant impact on the freeway route travel time reliability, while shoulder incident type has the least impact. Generally, HOV lanes have higher travel time reliability than GPLs under the same incident types. The findings in this study provide useful decision support for transportation agencies to improve travel time reliability on freeways.

In this paper, the shortest paths search for all departure times (profile search) are discussed. This problem is called a time-dependent shortest path problem (TDSP) and is suitable for time-dependent travel-time analysis. Particularly, this paper deals with the &epsilon, approximation of profile search computation. The proposed algorithms are based on a label correcting modification of Dijkstra&rsquo, s algorithm (LCA). The main idea of the algorithm is to simplify the arrival function after every relaxation step so that the maximum relative error is maintained. When the maximum relative error is 0.001, the proposed solution saves more than 97% of breakpoints and 80% of time compared to the exact version of LCA. Furthermore, the runtime can be improved by other 15% to 40% using heuristic splitting of the original departure time interval to several subintervals. The algorithms we developed can be used as a precomputation step in other routing algorithms or for some travel time analysis.

This paper is focused on searching the shortest paths for all departure times (profile search). This problem is called a time-dependent shortest path problem (TDSP) and is important for optimization in transportation. Particularly this paper deals with the ε-approximation of TDSP. The proposed algorithm is based on a label correcting modification of Dijkstra's algorithm (LCA). The main idea of the algorithm is to simplify the arrival function after every relaxation step so that the maximum relative error is maintained. When the maximum relative error is 0.001, the proposed solution saves more than 95% of breakpoints and 80% time compared to the exact version of LCA. A more efficient precomputation step for another time-dependent routing algorithms can be built using the developed algorithm.

In this paper, we propose an optimization model for planning a robust path against changes in traffic volume. Robustness is based on the form of the travel time function. The proposed model can be applied not only when traffic volume increases but also when it decreases. In addition, the proposed model can set the ratio of consideration by a parameter depending on whether the traffic volume is increasing or decreasing. The effectiveness of the proposed model is evaluated using actual traffic data from the Kanto region in Japan.

Poznato je da nepovoljne vremenske prilike utiču na promene u efikasnosti funkcionisanja urbanih transportnih sistema. Kao rezultat uticaja najčešće dolazi do povećanja vremena putovanja i nivoa zagušenja ulične mreže. Usled visokog nivoa urbanizacije i porasta saobraćaja postalo je posebno značajno pažnju posvetiti svim potencijalno negativnim uticajima na performanse saobraćajnog sistema. To je u velikoj meri doprinelo intenzivnijem istraživanju uticaja nepovoljnih vremenskih prilika na saobraćajni sistem. Fokus doktorske disertacije je stavljen na kvantifikaciju uticaja nepovoljnih vremenskih prilika na elemente ponude transportnog sistema, i implementaciju dobijenih rezultata u proceduru modeliranja opterećenja ulične mreže. Ovo je posebno značajno jer većina postojećih modela i metoda koji se koriste u procedurama planiranja saobraćaja ne uključuju faktor uticaja nepovoljnih vremenskih prilika, odnosno optimizirani su za idealne vremenske prilike. Specifičnost analiziranog uticaja, u smislu prostorne i vremenske dinamičnosti je uslovila potrebu da kroz disertaciju budu razvijeni posebni metodološki pristupi kvantifikacije uticaja nepovoljnih vremenskih prilika na kapacitet ulične mreže i brzinu kretanja vozila. Razvijenim metodologijama istraživanja je povećan nivo osetljivosti i preciznosti identifikovanih promena kao posledica uticaja nepovoljnih vremenskih prilika. Kao rezultat istraživanja generisani su koeficijenti osetljivosti elemenata transportne ponude na analizirani uticaj. Kategorije nepovoljnih vremenskih prilika u okviru kojih su analizirane promene u elementima ponude transportnog sistema definisane su u odnosu na klimatske katarakteritike područja istraživanja. Implementacija uticaja nepovoljnih vremenskih prilika u modeliranje opterećenja ulične mreže je, pored istraživanja osetljivosti elemenata ponude transportnog sistema, podrazumevala i modifikaciju funkcije vremena putovanja u odnosu na analizirani uticaj. Funkcija vremena putovanja predstavlja jedan od najvažnijih ulaznih parametara procedure modeliranja. Iako je kroz disertaciju metodologija modifikacije funkcije vremena putovanja razvijena na konkretnom tipu funkcije, karakteriše je opšta primenljivost. Testiranje i verifikacija metodologije implementacije uticaja nepovoljnih vremenskih prilika u proceduru modeliranja opterećenja ulične mreže su realizovani na primeru Transportnog modela Beograda... It is generally know that adverse weather conditions cause changes in functional efficiency of the urban transportation system, which results in larger travel times and higher congestion levels in street networks. Considering urbanization and traffic increase, it became particularly important to pay attention to any potentially negative impacts on the transportation system performance. It has largely contributed to a more intensive research of adverse weather impact on the urban transportation system. The focus of this dissertation is quantification of adverse weather impact on the transport supply elements, and implementation of obtained results in the procedure of the street network assignment modeling. This is particularly important because most of the existing models and methods used in transportation planning does not include the factor of adverse weather impact, i.e. models and methods are optimized for ideal weather conditions. The specificity of the analyzed impact, in terms of spatial and temporal dynamics, has caused the need to develop particular methodological approaches for quantifying the adverse weather impact on the street network capacity and vehicle speed. Level of sensitivity and precision of identified changes caused by adverse weather impact by developed methodologies, was improved. As a research result the sensitivity coefficients of transport supply elements on the analyzed impact, are generated. Categories of adverse weather conditions within which were analyzed changes in the transport supply elements are defined according to climate characteristics of research area. Implementation of adverse weather impact in the street network assignment modeling is beside the research of transport supply sensitivity, also implied the modification of travel time function according to the analyzed impact. The travel time function represents one of the most important input parameters in street network assignment modeling. Although, the methodology of travel time function modification was based on a specific function type, it is characterized by a general applicability. Implementation methodology of adverse weather impact in the street assignment modeling were tested and verified in the case of the Transport model of Belgrade...

In this paper we evaluate the output from four headway-based public transport model variants for modeling the public transports in Stockholm, Sweden. The results from the four models are analyzed and compared to trip observations. The comparisons are based on model instances where the parameters in the generalized travel time function are calibrated. The best possible parameter values have been found using the calibration procedures SPSA and Compass search. Two different objective functions have been evaluated for the calibration. Numerical experiments have been performed using a public transport model implemented in Visum by Storstockholms lokaltrafik. For the calibration and analysis, trip observations from the Swedish national travel survey and data generated from a public transport trip planner are used. From the numerical results, it is concluded that it is of less importance to find the best possible parameter values in the generalized cost function than selecting the best model variant. For the Stockholm public transport model, the numerical results indicate that the models in the class of Random departure time models result in a better fit to the observed trips than the models in the class of Optimal strategies.

Mixed traffic systems dominated by motorcycles (MTSDM) are characteristic for developing countries like Taiwan, Vietnam, The Philippines, Thailand, or India. The present paper investigates a new travel time function including not only the driving time but also the waiting time at the signal line on a link in such a traffic environment. Foremost, a review of popular travel time functions with discussion about their advantages as well as disadvantages when applied in a traffic assignment (TA) model is discussed. Suitable parameters for applying the Bureau of Public Road (BPR) function to an MTSDM are calibrated after introducing a method to estimate the practical capacity of a link based on the certain saturation flow. The travel times calculated by the new BPR function turned out to be highly accurate when compared to the simulated travel time in VISSIM—a popular traffic visualization software. Moreover, the User Equilibrium (UE) model using the new function could forecast traffic flows close to the real flows collected in Hanoi,Vietnam.

Rainfall always has a direct impact on the travel time reliability of the highway network. Taking into account the adverse driving conditions under rain environment, such as poor visibility and low friction coefficient, the improved model of free flow speed, capacity and demand is established based on the analysis of spatial distribution pattern of rainfall. Thus, the generalized road travel time function is proposed to elaborate these factors. With user optimal equilibrium assignment formula and the series-parallel theory, the model to evaluate the travel time reliability of the road unit, path, OD pairs and network system is proposed by analyzing the network supply and demand levels. Then, the distribution of the rainfall on the highway network is simulated by the Matlab toolbox, and the model is solved with the Monte Carlo methods. Finally, a simple example illustrates the methods in the application to evaluate the travel time reliability of highway network under rain environment. The results indicate that the methods enable effectively identify the critical road sections with high sensitivity about travel time in the network.

This article presents a game-theoretic model of information transmission for variable message sign (VMS) operations. The model contains one VMS operator and many drivers. The operator wants to minimise the total travel time of all the drivers, while each driver wants to minimise his own travel time. The operator, who knows the actual traffic situation, sends drivers’ the traffic information strategically. The drivers evaluate the information from the operator, and then choose their optimal route. We model this situation as a cheap-talk game, which is one of the simplest forms of a Bayesian game. Depending on the shapes of the travel time function, the optimal information provision in equilibrium varies from full provision to partial provision.

This study examined the detection of the Braess Paradox by stable dynamics in general congested transportation networks. Stable dynamics, suggested by Nesterov and de Palma (2003), is a new model which describes and provides a stable state of congestion in urban transportation networks. In comparison with the user equilibrium model, which is based on the arc travel time function in analyzing transportation networks, stable dynamics requires few parameters and is coincident with intuitions and observations on congestion. It is therefore expected to be a useful analysis tool for transportation planners. The phenomenon whereby increasing network capacity, for example creating new routes, known as arcs, may decrease its performance is called the Braess Paradox. It has been studied intensively under user equilibrium models with the arc travel time function since it was first demonstrated by Braess (1968). However, the development of a general model to detect the Braess Paradox under stable dynamics models remains an open problem. In this study, we suggest a model to detect the paradox in general networks under stable dynamics. In our model, we decide whether the Braess Paradox will occur in a given network, detect Braess arcs or Braess crosses if the network permits the paradox, and present a numerical example of the application of the model to a given network.

Although time constraints on travel behavior have been widely recognized, little effort has been made to incorporate such constraints into the traditional stochastic user equilibrium (SUE) framework. The major objective of this research is to fill this gap by incorporating travel time constraints into the SUE model by means of a nonlinear perceived travel time function. This modified model, designated the travel time budget model, focuses primarily on discretionary travel behavior (such as shopping trips) and hence also allows the possibility of deferring travel decisions by incorporating an additional choice alternative designated the shop-less-frequently alternative. This model is compared with the traditional SUE model by using a simulated travel scenario on a test network designed to reflect a practical planning situation. The simulation shows that when attractiveness levels are increased by the introduction of a new shopping opportunity, the presence of travel time constraints can lead to significantly smaller predicted travel volumes than those of the traditional SUE model. More important, it shows that the overall pattern of travel can be quite different. In particular, travel to the shopping destination with enhanced attractiveness can actually decrease for some origin locations. The findings suggest that when an attempt is made to evaluate the impact of planning alternatives on future traffic patterns, it is vital to consider not only the cost of time itself but also the time trade-offs between travel and other human activities.

This paper reports on the findings of pedestrian flow characteristics for different types of walking facilities in Hong Kong. Surveys were conducted during peak hours at indoor and outdoor walkways, signalized crosswalks with and without midblock, signalized and nonsignalized crosswalks leading to light-rail transit stations, and five types of walking facilities in railway stations. The collected data were used to develop speed/flow relationships and to calibrate the travel time function for each type of pedestrian facility. Pedestrian flow characteristics on various walking facilities are also compared. The collected data and the established relationships could be used as a basis for the development of pedestrian simulation models for Hong Kong and/or other Asian cities with similar pedestrian characteristics.

In this paper we develop a new theory of static equilibrium in congested transportation networks. We show that under some natural assumptions, the Wardrop principle leads to a very strong relation between the loading of the arc, arc flow and arc travel time. This relation allows us to simplify significantly the arc performance model. We show that instead of fixing a functional form of travel time function, we can obtain equilibrium solutions for static traffic assignment models using only some natural bounds for arc travel time and arc flow. We compare the results of our model with the results of standard Beckmann model.

Considering characteristics of Chinese urban mixed traffic, the author develops a combinatorial model involving the mixed deterministic traffic volume distribution and user’s equilibrium (UE) assignment on the basis of symmetrical link travel time function (or deterrence). Its uniqueness and equivalance to the Wardropian principle of UE are also proved. Finally, we give the algorithm of model.

This paper reports an investigation on the pedestrian travel timefundions for various pedestrian facilities in the Hong Kong Mass Transit Raifwoy (MTR) stations. As the pedestrian walking behavior con be influenced by the physical properties of the walking facilities, different pedestrian facilities are classified for analysis. Surveys were conduded in the Hong Kong MTR stations and the data collected were used to develop fifteen sets of pedestrian travel time function for the classified pedestrian facilities. The data colleded were also compared with the previous research findings for London underground stations. Further more, to examine the reliability of the travel time functions, the calibrated functions were validated by independent observed data and incorporated into a pedestrian simulation package for evaluation. The calibrated functions could be used as a basis for the development of pedestrian simulation models for the underground stations in Hong Kong.

This paper presents a survey of the mathematical methods used for modeling and solutions for the traffic assignment problem. It covers the static (steady-state) traffic assignment techniques as well as dynamic traffic assignment in lumped parameter and distributed parameter settings. Moreover, it also surveys simulation-based solutions. The paper shows the models for static assignment, variational inequality method, projection dynamics for dynamic travel routing, discrete time and continuous time dynamic traffic assignment, and macroscopic dynamic traffic assignment (DTA). The paper then presents the macroscopic DTA in terms of the Wardrop principle and derives a partial differential equation for experienced travel time function that can be integrated with the macroscopic DTA framework.

This paper is focused on the pedestrian flow characteristics for passage in subway stations and railway station in Beijing. By collecting and analyzing the data, the paper finds the different of the pedestrian speed characteristics between two kinds of transit hubs. The collected data were also used to develop speed/flow relationships and to calibrate the travel time function. By making an investigation, the paper sets up the passage indexes system to research the indexes which affect the pedestrian speed, and also establishes the method of computing.

The network flow constraints construct the feasible region for dynamic travel choice models. Although the feasible region associated with each dynamic travel choice model may be different, the basic components of the network flow constraints are essentially the same. The complete requirements of dynamic travel choice models include the constraints of flow conservation, flow propagation, nonnegativity, definition, first-in-first-out (FIFO) and oversaturation.

Why does a consumer choose a variant of a product rather than another one? The commonly invoked reason is that of the consumer’s preferences: he prefers the variant which is best for him. If the price is the only attribute which distinguishes the variants from one another, the consumer chooses the cheapest variant and he can be described as a cost-minimizing (or utility maximizing) economic decision maker.

Dynamic route guidance systems are being developed to inform and guide drivers regarding their best departure times and routes so as to avoid congestion delay. However, some drivers may not rely on the information provided by the route guidance system to adjust their departure times and routes. Furthermore, drivers without navigation systems do not have perfect information on the network traffic and must use their own experience and perception of current traffic conditions to make travel decisions. Thus, there is a need to develop dynamic route choice models under imperfect as well as perfect information.

In this chapter, we first present optimal control formulations for instantaneous dynamic user-optimal route choice problems. In Sections 8.1 and 8.2, we present two instantaneous dynamic user-optimal route choice models. The equivalence of Model 1 with DUO route choice is demonstrated by proving the equivalence of the first order necessary conditions of the model with the instantaneous DUO route choice conditions. The second DUO model employs a different link travel time function assumption; its equivalence with the instantaneous DUO route choice conditions is also demonstrated. In Section 8.3 and 8.4, we generalize the variational inequality model of Chapter 7 to the situation of travel disutility and multi-class travelers instead of travel times for a single class of travelers only. The multi-class route-cost-based variational inequality model is first presented in Section 8.3. Then, the multi-class link-cost-based variational inequality model is presented in Section 8.4.

In this chapter, the constraints for dynamic traffic necessary for a urban transportation network are presented. These constraints include flow conservation for links and nodes, flow propagation, first-in-first-out (FIFO) and oversaturation. Associated with these constraints and different needs for dynamic travel time information, two definitions of travel time are considered.

In this chapter, we discuss optimal control models for instantaneous dynamic user-optimal route choice problems. Using a network with two parallel routes, we first present an example to illustrate the instantaneous dynamic user-optimal concept in Section 5.1. The general definition of instantaneous dynamic useroptimal state is given in Section 5.2. Then, we present three instantaneous dynamic user-optimal route choice models. Model 1 is described in Section 5.3. In Section 5.4, the equivalence of Model 1 with DUO route choice is demonstrated by proving the equivalence of the first order necessary conditions of the model with the instantaneous DUO route choice conditions. In Section 5.5, the second DUO model employing a different link travel time function assumption is formulated, and the equivalence of Model 2 with the instantaneous DUO route choice conditions is also demonstrated. In Section 5.6, the third instantaneous DUO model employing a simpler link travel time function assumption is formulated, and its equivalence with the instantaneous DUO conditions is also demonstrated. Finally, we present a discrete-time numerical example indicating that this class of models yields realistic results.

A satisfactory approximation to the travel time of a reflected wave is achieved by finding a ray, which originates in the source and emerges close enough to the receiver. The reason for this is, that the actual travel time function can be approximated in every emergence point of the wave by a time function which is entirely defined by seismic parameters along the ray connecting the source with the point of emergence.