Sharif Digital Repository

Left-turn operation is a critical component in the safe and efficient operation of a signalized intersection. The proper type of left-turn phasing results in reduction of traffic delay and number of accidents. A review of the literature indicates that different warrants have been proposed for the installation of the protected left-turn phase; however, there is not a consensus to implement a specific warrant up to the present. In general, the warrants fall into four categories: traffic volume, operational characteristics of traffic, intersection geometrics and accident experiences. Considering the high rate of accidents resulting from left-turn movements at signalized intersections in Iran,... 

Identification of hazardous locations and improvement of these locations are the basis of most highway safety inspection programs. In most cases, performance of successful highway safety management programs requires accurate accident data, and availability of these data. Unfortunately, in Iran, there is some uncertainty about the accuracy and completeness of these data to be used in a safety management program.The main purpose of this study is to identify and compare highway accident hazard index for a two-lane rural highway in Iran using two different methods. In the first method, traffic and alignment characteristics of the highway were recorded through roadway auditing technique, GPS... 

High number of traffic accidents in Iran and its rate which is well above the world's average is a major issue of concern. The results of recent researches show a direct relation between survival rate of traffic accidents' injuries and the Emergency Response Time (ERT). The main objective of this research is to analyze different aspects of ERT in Tehran, Iran and to compare these results with the International standards. This study intends to compare the selected routes by ambulance drivers with the shortest paths recommended by EMME/2. Results of analysis show that when the travel time between accident scene and the emergency dispatch center is less than 8 minutes, the possibility of... 

Estimation of travel time in transportation engineering has always been an important issue. So far, most of travel time studies have focused on freeways and highways, and very few research have been done on travel time estimation for arterials. In this study, by using shock wave concept, a probabilistic model is developed for estimating the travel time of a signalized arterials consisting of two pre-timed signalized intersections. This model can be used in both coordinated and non-coordinated signals. In this study, travel time and traffic volume data were collected for Fatemi Ave. in Tehran, Iran. By using these data, some parameters of VISSIM simulation package were calibrated to reflect... 

Traffic accidents, is an inevitable event. There are various reasons for accidents and almost not possible to identify all of them, but a careful study of these phenomena can identify the main causes of this phenomenon. This study estimates Multi-Vehicle severity in terms of different weather. Accidents data the Including 2,949 accidents recorded during 1388 to 1392 in six axes of the East Azerbaijan roads in three levels of accident severity: damage, injury and death. For modeling, sequential Logit model was selected because accidents severity have Sequential nature. This model used the Stata software, version 12, for evaluation and sensitivity analysis. The obtained model consists of... 

Nowadays, there are three factors in traffic issues, which are very important. These factors are delay time, fuel consumption and environmental pollution. A good choice of the type of traffic nodes (intersection and roundabout) can play an important role in reducing some of the traffic problems such as: the amount of vehicles' delay time, energy consumption and pollution due to the transport system. In this study, we try to identify factors that influence delay time, fuel consumption and air pollution in different types of intersections and roundabout. According to previous studies, these factors were such as: variables of each route volume, distribution of through, right turn and left turn... 

For any country, the road system is an important part of its infrastructure which can affect economic development. A good level of service for a road system requires implementation of work zone projects to maintain it which usually close one or more of the lanes available for traffic. Lane reductions could cause a disturbance to normal traffic flow and speed reductions, further resulting in a reduction of road capacity and an increase of traffic delay. In addition, work zone capacity and traffic delay are the two critical indices to determine whether the effectiveness of traffic control systems is acceptable or not. Hence, the accurate estimation of capacity and traffic delay in work zones is of... 

Natural disasters, earthquakes in particular, claim many human lives and damage major lifelines such as transportation networks. Transportation networks play an important role in various stages of response to disasters, such as evacuation, search, rescue and reconstruction missions. Hence, special attention must be paid to transportation networks in any disaster management system. Hence, in order to reduce the impacts of earthquakes on denser cities and metropolitan areas, analysis of the resiliency and vulnerability of critical infrastructures such as transportation network, can be used as an effective strategy.The resiliency and vulnerability of transportation network have attract a lot... 

The lack of road safety imposes heavy costs on society. The cost of treatment, disability, travel time and mental disorders are examples of costs caused by unsafe roads in a country. One of the most effective manners to improve road safety over the last decade is to use safe driving incentives and in particular usage-based insurance. Usage-based insurance reduces road accidents by internalizing the cost of driving violations and the cost of vehicle usage.Risky behaviors and driving violations, especially speed limits violations, have a significant effect on increasing unsafe road traffics. Accordingly, in this Ph.D. dissertation, a new scheme of usage-based insurance was introduced to reduce... 

The road authorities of a city have the responsibility of constantly assessing how well their city performs when traffic conditions are taken into account. In many metropolises around the world, if not taken preventive measures, there will be observed a density above the network capacity and a noticeable decrease in the level of service, especially in the morning and evening peak hours. Also, the dynamic congestion pricing of certain areas based on the traffic condition has always been considered significant by urban planning officials. Since this is not possible except by constantly assessing the current traffic state, a variety of methods have been used to predict the future traffic... 

Road casualty is the fourth leading cause of death in Iran after cardiovascular disease, cancer, and respiratory disease. Moreover, up to 7% of Iran’s Gross Domestic Product (- GDP) is spent annually on motor vehicle crashes’(MVCs) adverse outcomes. Recent studies have highlighted the role of anger and aggressive behaviors, while driving as two main predicters of MVCs. On the other hand, bus drivers and passengers, compared with the small number of registered buses in Iran, are more prone to fatal crashes than occupants of any other vehicles, based on the last WHO’s report. The aim of current research was to evaluate the influence of aggressive thoughts and behaviors on the road, driver’s... 

Human error is one of the most important causes of accidents. Distraction and lack of attention to driving, fatigue, poor vision, speeding, and other such errors by drivers can cause accidents. With the rapid advancement of technology, transportation planners also thought of making cars as smart as possible to reduce human error. In this study, the effect of self-driving cars on the number of accidents at two unsignalized intersections is investigated using traffic microsimulation. For conventional vehicles, the factor considered for the simulation and calibration is driver distraction, which may be caused by reading or writing a text message on a cellphone or other items. This factor can be... 

Technology is changing the travel behavior of people around the world. Automated vehicles offer new solutions to some of the problems in transportation. This technology can improve traffic safety, land use development, traffic quality, and fuel consumption. Nevertheless, these solutions can be applied, only if Automated Vehicles are accepted and used by people. Due to a lack of mass production in the industry yet, automated vehicles’ adoption and market share are not yet determined and therefore certain to happen. This study surveyed 334 Iranian truck drivers in October 2019 to examine their opinions of heavy-automated vehicles (i.e. automated trucks), the factors and variables that affect... 

Road casualty is the fifth leading cause of death in Iran. To adopt proper countermeasures there is a need to evaluate the consequences of the implemented policies. Despite the development of crash time series models, these methods have not been in accordance with the multivariate, seasonal, and non-linear nature of crash data. On the other hand, the interpretable crash causal analysis frameworks are descriptive and they lack predictive power. Moreover, the unobserved homogeneity between observations has been widely overlooked in the crash causal analysis literature. This thesis introduces a novel causal analysis methodology by combining the interpretability and prediction power of the... 

Autonomous Vehicles have received much consideration in different trends in recent two decades. Autonomous Vehicles refer to vehicles that can drive without a driver and perform all driving tasks automatically, so eliminating the driver's role can affect various aspects. In this research, the effects of Autonomous Vehicles on the improvement of the traffic condition is studied. To this end, freeway’s performance parameters including travel time and traffic speed at the time of a traffic accident in mixed traffic conditions have been simulated. Considering that the braking behavior, acceleration, and speed changes of the Autonomous Vehicle are effective on the evaluation parameters, five... 

Autonomous vehicles (AVs) offer numerous advantages in reducing traffic accidents, alleviating congestion, and enhancing mobility for special populations such as the elderly and disabled. However, for society to truly benefit from these advantages, widespread acceptance and usage of these cars are necessary. It is crucial to identify the factors that promote acceptance of these cars in different societies and take action to strengthen them, involving both governments and car manufacturers. So far, most studies on AVs acceptance models have primarily focused on developed countries, with less attention given to how people in developing countries perceive this technology. Additionally, previous... 

Pedestrian accidents involve most of traffic accidents mainly happen in urban intersections (signalized or non-signalized). The present research is to identify and evaluate the factors influencing the pedestrian decision while crossing the street at signalized intersections. The data used in this study are captured by recording the behavior of 596 pedestrians while crossing 2 signalized intersections in Karaj. To better identify the variables affecting the behavior of pedestrians, such as age, education, etc., 394 people have been interviewed in person. The factors affecting the pedestrian behavior are divided into two general groups: 1- Social, demographic, economic, family, and other... 

Traffic flow modeling on different levels was always the topic of many studies. In this regard, many researchers have tried to eliminate traffic problems by developing precise models. Therefore, in this study and in its two major parts, we developed two models: one macroscopic and one microscopic. Like previous studies, the main purpose here was the development of traffic flow models that have better precision and give more information about the mechanism behind the traffic phenomena. Our focus was on the free spaces in front of drivers which were considered in a macroscopic traffic flow model and resulting microscopic traffic flow model.First part, addresses the first-order extension of the... 

Lately, there has been a great attention to accident prediction methods in traffic management. The importance of predicting an accident is because of its enormous effect on reducing casualties, injuries, property damages and delays. The main objectivein this study was to identify the relationship between accidents frequency rates and geometric design variables, climatic parameters and traffic characteristics using probabilistic models. The other objective was to evaluate the crash severity and crash type. Therefore, the 1997 traffic accident statistics of city of Mashhad in Iran was used for the for the modeling of different highway classification. Probabilistic models are used for... 

In recent years, most of the researches in Urban Transportation Planning have been in the areas of prediction and management of transportation demand, increasing the capacity of roads and reducing traffic congestion. In spite of several studies which were performed in the field of collisions prediction modeling for highways and freeways, these models were not applicable to long-term transportation planning process due to their inability to accurately predict variables for future long-term transportation planning.In this study, Aggregate Crash Prediction Models (ACPMs) were performed using the Socio-economics, land use and street network information of 253 traffic zone. This information was...