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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...

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.