Traffic congestion has been rapidly increasing in cities. It leads to an increase in transit travel time and loss in reliability of transit vehicles. The implementation of the priority system for transit at signalized intersections with high traffic volumes will help reduce transit delays and red lights stops at these intersections. In this paper, we propose an unconditional active signal priority control method for public transportation system, which includes regular buses and a Bus Rapid Transit. we examined 11 different modes of bus availability at the intersection, based on the estimated time of transit arrival. Reduce transit delays at the intersection, increase the convenience and reliability of public transportation, increase the total intersection efficiency and reduce the negative impact on personal vehicles are also considered. Finally, a model simulation was conducted by VISSIM by writing an algorithm modeling in a signalized intersection with BRT and regular bus in Isfahan City, Iran. the results showed that, due to the implementation of this method, BRT passengers delay decreased by an average of 65% and decrease regular bus passengesrs delay by an average of 7% comparing to existing signal control scenarios.

The purpose of this study is how the RCUT intersection works in different traffic volumes. To evaluate the intersection, the volume to capacity ratio of 0.9, 0.6, and 0.4 was used to check the performance of the intersection during peak hours. Also, with the aim of choosing the best type of the intersection, changes in the geometric design of the intersection were made and evaluated. Nine scenarios were experienced in four main designs to evaluate all intersection types. These designs include the RCUT intersection, two-lane roundabout, reduced intersection light timing, and dog-bone roundabout. Then, VISSIM software was used to simulate these scenarios and the results of the obtained parameters such as queue length, delay, level of service, number of the vehicle stops and the percentage of pollutants of all scenarios were compared with each other using the multi-criteria decision-making method. Results indicate that the best scenarios included increasing the median width from 7.5 m to 11 m, increasing the median width in the roundabout from 7.5 m to 11.3 m, and increasing the distance of the roundabout from the intersection from 137 m to 183 m, which caused the queue length to decrease by more than 50%. There has been a reduction in delays and stoppages by nearly 20% and associated with pollutants and fuel by nearly 5%. At the end, using the multi-criteria decision-making method, the best scenario, and reducing the optimization of timing of the lights was determined. In this scenario, the queue length results were 50% less than other designs, the level of service was one level higher, and a 25% reduction in delay and stoppages was observed.

In most freeway, because of heavy vehicle and truck move, we see several accidents. Transition limitation for heavy vehicle of passenger car with using of specific lines technic is essential. This research have been compared existence and inexistence line limitation in Iran freeway. For scenarios comparison, we use VISSIM traffic stimulation software and for case study, we investigate some part of Qom-Tehran freeway. After modeling this limited area, we calibrated model. Then with effective parameters changing, we create different scenarios and then each scenario have been model building and after software enforcement, outputs have been investigated. At the end, scenarios have been compared base on traffic. Function, and advantages and disadvantages investigated for using in zran. Line limitation for heaby vehicle is fitted (4%) other than line limitation inexistence.

Due to an increase in goods transportation and movement of heavy gravity vehicles, high-volume freeway routes include a level of safety reduction. The aim of this study is to explore the effect of heavy gravity vehicles restriction on passenger vehicles to reduce their interactions, which is necessary for the use of special lanes or lane restriction for heavy gravity vehicles. Lane restriction for heavy gravity vehicles is a method that is commonly employed in this country, but is lacking any detailed academic studies. In addition, this paper presents efforts to determine a comprehensive and suitable criterion for specifying appropriate use of lane restrictions on a freeway or highway. In this research, the presence or absence of lane restrictions for freeways in Iran are investigated, along with a comparison of those two modes and the influence of several parameters on that process. To this end, in order to compare the scenarios, the traffic simulation software VISSIM and a section of the Tehran-Qom freeway was used as a case study. Also, in order to evaluate safety, the SSAM software was used, and to ensure maximum compatibility with the specified situation, its calibration and validity was examined. From this research, the presence of lane restrictions for heavy gravity vehicles was shown to improve operational performance by about 4%, and in terms of safety, the presence of lane restrictions was shown to be somewhat weaker than the lack of them. This conflict between operational performance increment and safety reduction based on lane restriction is related to the accumulation of heavy gravity vehicles in right-hand lanes and the complications of vehicles changing lanes for exit from the freeway and entering the ramp.

2Jitneys have special behavior and suddenly change lanes for boarding and alighting of passengers. These vehicles cause irregularity in and a lot of delay on traffic flow by unexpected maneuvers and stops in anywhere of streets. Its importance issue that we force taxies to stop only at taxi stops and subsequently assess the effect of this restriction on improvement of traffic parameters.This research is carried out for assessing the effect of taxi stops position on traffic performance of an urban street. The approach was based on simulation of taxi behavior in a sample street by VISSIM simulating software. The real data of traffic flow and taxi behavior has been collected from a sample two-lane street in the city of Tehran. Performance parameters like travel time, delay and average speed are determined on the basis of software results for different scenarios. Results are compared and the best scenario is illustrated. Results indicate that taxi stops in one and two lane streets have considerable effects on street traffic performance and increase travel time and delay of vehicles.

Intersections are considered as the most critical parts of the Bus Rapid Transit (BRT) system. Transit signal priority is one of the efficient solutions to reduce BRT fleet delays at intersections. The aim of this study is to propose a new algorithm to decrease the BRT fleet delays at actuated intersections, while reducing the negative impacts on different approaches. The adaptive strategy is applied in this study. In the proposed algorithm, named TSPAT (Transit Signal Priority for Actuated Timing), intersection phasing is rescheduled, based on traffic conditions such as phase conditions at the time of bus arrival, the queue length of other approaches, and prioritization record in a specific time length. To assess the merits of the proposed algorithm, a before-after study is executed by applying VISSIM traffic simulation software for an actuated intersection in Isfahan city, Iran. The simulation results show that by applying the algorithm, the average delay of BRT fleets is declined by 21 % and 51% in peak and off-peak hours, respectively. Furthermore, the average speed of BRT fleets is increased by 26% and 78%, during peak and off-peak hours, respectively. The utilization of TSPAT algorithm can improve the desirability of the public transportation system along the BRT routes.

Traffic simulation represents an effective tool for evaluating the suggested alternatives to enhance traffic conditions prior to their application in real sites. U-turn sections represent examples of the complicated sections that cannot be analyzed properly without applying microsimulation approach. Recently, in Iraq, speed humps were applied in prior to the merging locations and U-turn sections to enhance traffic safety. However, the characteristics of traffic at U-turn section with the presence of speed humps have got little attention in previous literatures. This paper uses VISSIM microsimulation model to emulate traffic movements at selected U-turn sites in the cases of with and without speed humps. Three median U-turn sites have been selected where two of these sites have speed humps prior to the turning locations. Real traffic data have been obtained from these sites using video recordings to estimate specific parameters. The developed simulation models were successfully calibrated and validated with the real data. The models have been used in testing different scenarios including the effect of having different locations/ types of speed humps and finding the capacity of U-turn sections. The results showed that closer the speeds hump to the turning location is lower the time spent for merging. The time spent values are increased with the increasing of traffic speeds at humps. Higher capacity value is obtained for the site with an auxiliary lane and speeds hump compared with the other sites.