Transportation Network Modeling and Simulation

Traffic microsimulation is an essential tool in urban transportation and road planning. Its calibration is essential to attain representative results validated with real-world conditions. VISSIM (Verkehr in Städten-SIMulationsmodell) operates with the Wiedemann's psycho-physical car-following model for freeway travel that considers safety distances (standstill and movement) during simulation. Calibration in this paper was achieved by using two different approaches: a) manual and b) genetic algorithm (with the GEH statistic formula) calibration techniques. Calibration and validation of this model were performed at the Periferico de la Juventud expressway in Chihuahua City, in northern Mexico. The Periferico de la Juventud (PDJ) has a N-S orientation and a length of ca. 20 km, with its northern section being its most congested portion. Its highest vehicle volume occurs at noon, with 3700 vehicles per hour, with 95% being passenger cars and the other 5% heavy goods vehicles. PDJ's speed limit is 70 km•h −1 , but the driver's behavior has a tendency towards the aggressive performance. A total of 82 standstill and 82 look-ahead distances were obtained from unmanned aerial vehicles (UAV) images, with values ranging from 0.8 to 4.7 m and from 0.2 to 28 m, respectively. VISSIM calibrated parameter values were calculated for this expressway, being slightly above than the VISSIM default ones; and was validated with travel times and look-ahead distances. Results contribute information for the city's future installment of public transportation systems, and should help decision makers deal with future urban planning.

Abstract—We describe the various aspects involved in building FastTrans, a scalable, parallel microsimulator for transportation networks that can simulate and route tens of millions of vehicles on real-world road networks in a fraction of real time. Vehicular trips are generated using agent-based simulations that provide realistic, daily activity schedules for a synthetic population of millions of intelligent agents. We use parallel discrete-event simulation techniques and distributed-memory algorithms to scale these simulations to over one thousand compute nodes. We present various optimizations for speeding up simulation execution times, including (i) a set of routing algorithms such as variations of Dijkstra’s shortest path algorithm and heuristicbased A ∗ search, and (ii) a number of different partitioning schemes for load balancing, including geographic partitioning (that assigns simulation entities that are geographically close by to the same processor) and scattering (that as...

Traffic microsimulation is an essential tool in urban transportation and road planning. Its calibration is essential to attain representative results validated with real-world conditions. VISSIM (Verkehr in Städten-SIMulationsmodell) operates with the Wiedemann's psycho-physical car-following model for freeway travel that considers safety distances (standstill and movement) during simulation. Calibration in this paper was achieved by using two different approaches: a) manual and b) genetic algorithm (with the GEH statistic formula) calibration techniques. Calibration and validation of this model were performed at the Periferico de la Juventud expressway in Chihuahua City, in northern Mexico. The Periferico de la Juventud (PDJ) has a N-S orientation and a length of ca. 20 km, with its northern section being its most congested portion. Its highest vehicle volume occurs at noon, with 3700 vehicles per hour, with 95% being passenger cars and the other 5% heavy goods vehicles. PDJ's speed limit is 70 km•h −1 , but the driver's behavior has a tendency towards the aggressive performance. A total of 82 standstill and 82 look-ahead distances were obtained from unmanned aerial vehicles (UAV) images, with values ranging from 0.8 to 4.7 m and from 0.2 to 28 m, respectively. VISSIM calibrated parameter values were calculated for this expressway, being slightly above than the VISSIM default ones; and was validated with travel times and look-ahead distances. Results contribute information for the city's future installment of public transportation systems, and should help decision makers deal with future urban planning.

Trafik sıkışıklığı, günümüz metropollerinin en büyük sorunlarından birisidir. Dünyada her gün milyonlarca saat trafik sebebiyle boşa gitmekte, çalışanların ve öğrencilerin verimi düşmektedir. Trafiği azaltmak için trafiğe katkıda bulunan etkenlerin tespit edilip çözüm yoluna gidilmesi elzemdir. Çözüme yönelmeden önce sorunun asıl kaynağı iyice tespit edilmelidir. Hatalı tasarlanan ulaşım altyapıları yahut plansız kentleşme bu kaynakların en önemlilerindendir. Bu çalışma, İstanbul'daki toplu taşıma ağının analiz edilerek şehirdeki yapısal darboğazların tespit edilmesini amaçlamaktadır. Otobüs güzergahlarının konumsal ağ şeklinde kurgulanıp analiz edilmesiyle trafik yoğunluğunun oluşabileceği noktalar tespit edilmiştir ve tespitler gerçek hayat deneyimleriyle uyumludur.

Traffic congestion is one of the major problems of metropolitan cities. Each day millions of hours are wasted due to traffic congestion in the world, causing reduction in productivity among workers and students. In order to reduce traffic congestion, it is required to figure out major factors contributing to the congestion. The faults in the design of the transportation infrastructures or unplanned urbanization are some among the most important factors. This study aims to detect bottlenecks in the transportation network of Istanbul via network analysis. We detected potential traffic congestion points using bus line route information represented as a spatial transportation network. Our detections are complying with our real life experience.

This paper is an endeavor to picture excessive population threats to the resiliency of a large metropolitan area. By employing an existing evolutionary model of traffic flow on a small expository network, we show how chaotic situations occur at certain demand and supply parameter values, and try to address the questions: How may one determine city population capacity for its transportation network, what happens if the city passes this limit, or how may one return the city to a stable situation when it runs into unstable or chaotic situations. Under certain assumptions, the paper designs a simulation experiment to revisit the phenomenon discovered by Greenshields in 1934, but for a transportation network in a large city. A flow simulation shows that very small changes in the demand and supply of the network result in large variations in the throughput of the network, such that the time series of the latter values to an external observer are chaotic (with positive Lyapunov exponent). The limit to the resiliency of the city from the standpoint of its transportation network capacity is, then, estimated by a value for the city's population. It is then argued how to take the network out of this situation.

To overcome deficiencies of the sequential transportation planning approach, this research applies a Combined Trip Distribution and Assignment Model (CTDAM) for the simultaneous prediction. The proposed combined model can itself be reformulated as an Equivalent Minimization Problem (EMP). When applying the Evans algorithm to the EMP, the CTDAM is expected to be usable in a realistic application. The objective of this research is to compare the conventional sequential procedure and CTDAM by applying both models to a large urban transportation network for captive trip purposes. Several evaluation measures were utilized to compare the results and confirm that the proposed model can efficiently satisfy several convergence criterions. It became clear that the User Equilibrium (UE) assignment in the proposed model can be obtained relatively swifter than the Sequential Model (SM) and can be efficiently used in large transportation networks. Furthermore, the comparing results point out the performance of the CTDAM is significantly better than SM.