امین میرزا بروجردیان

The network design problem, functioning as a decision-making framework, embodies a policy-based orientation. This problem finds its conceptual footing in the realm of cost optimization, with a key emphasis on the travel time-related expenditures. However, the scope of costs in the network design problem extends beyond travel time. This study undertakes a meticulous exploration of the ancillary costs stemming from safety shortcomings and accidents and introduces the novel concept of the Safe Network Design Problem (SNDP). The investigation of this issue was carried out using the Sioux Falls network as a case study in LeBlanc's model, shedding light on the optimal network improvement strategy. The LeBlanc problem, comprising a selection among five projects within a budget constraint, resulted in the optimal scenario of 10110, indicating the execution of the first, third, and fourth projects. The introduction of safety as a key factor in the problem, particularly in the context of LeBlanc's example, yields intriguing results. In this scenario, the solution shifts to 01110. The combined approach that encompasses travel time costs and accidents, coupled with a comprehensive sensitivity analysis that accounts for accident severity and weighting, engenders a paradigm shift in the solution to the problem.

The road network represents a fundamental component of a city's infrastructure, catering to the needs of its populace. The design and provision of an efficient urban transportation network wield a direct influence on the quality of services demanded by users and concurrently serve as a linchpin for advancing other infrastructure development. Given this context, a pivotal requirement emerges to formulate inclusive urban networks that systematically incorporate critical medical components within their design. A salient observation lies in the fact that the foundation of city road network design predominantly revolves around enhancing the travel time for transportation network users, while other aspects, notably user safety, have been overlooked. The primary hurdle in road network design revolves around discerning the optimal choice for improving the network taking into account the numerous constraints embedded in the problem. Typically, this challenge is addressed through a dual-level model, where the lower level grapples with the intricacies of traffic flow assignment, and the upper level navigates the complexities of determining the most fitting network enhancement option, guided by the objective function of travel time. To address the identified gap, this study integrated indicators and models for accident prediction and to investigate the safety impact, the problem was solved in the Sioux Falls network. The answer to the Sioux Falls problem in LeBlanc's classic study is 10110. However, with the inclusion of the accident index of intersections and nodes, the answer to the problem was completely different.

Pedestrians as vulnerable road users have a very high sensitivity facing vehicles. The number of pedestrians killed or injured in traffic accidents is very significant which a noticeable percentage of them have occurred at un-signalized intersections. Four-leg un-signalized intersections are parts of the road network in which pedestrians are unsafe. In this paper, the main purpose is investigation of pedestrian safety facing vehicles at functional area of four-leg un-signalized intersections. Therefore to evaluate the traffic conflict safeties, Time to Collision (TTC) and Post Encroachment Time (PET) indexes were used. Particularly The effect of pedestrian characteristics on the safety level of conflict was evaluated by collecting field information and statistical studies. The data was obtained by video-recording of the functional area of Imam Hossain intersection in Hamadan city and then using ANOVA statistical analysis, the effect of pedestrian characteristics on the safety level of intersection was evaluated. Results show that:-The male pedestrians are safer than female (The differences between them at PET and TTC indexes are 0.11 and 0.08, respectively). -The young pedestrians are safer than elderly (The differences between them at PET and TTC indexes are 0.10 and 0.04, respectively). -The right-direction pedestrians are safer than left-direction (The difference between them at PET index is 0.03).

In freeways, in addition to assessing the traffic performance at the entrance ramp section to the freeway and its impact on vehicle delays, temporary functional changes may be necessary in certain freeway sections. Such changes could involve the temporary closure of one or several lanes along a specific stretch of the freeway for various reasons, including maintenance and repairs. The closure of one or several freeway lanes, when the flow of freeway traffic converges with the traffic from the entrance ramp, requires specific study and examination for various considerations. The Guide to Road Capacity did not previously address the examination of delays caused by the work zone area at the entrance ramp to the freeway. This study addresses this gap using the simulation software Aimsun. The study aims to measure the effects of interferences caused by the presence of the Work Zone area, the number of freeway lanes, the blocked freeway lanes, the entrance ramp lanes, and the length of the acceleration lane on travel time, comparing it with the Guide to Road Capacity in more detail. Considering the criteria in the Guide to Road Capacity, it was observed that in the convergence of 2 lanes to 1 lane, the main input flow volume and the entrance ramp flow volume had the most significant impact on the number of interferences and travel time. The variable of the acceleration lane length in this case had a more significant reduction effect on the number of interferences and travel time compared to other scenarios.

According to the statistics of the Iranian Legal Medicine Organization in 2019, about 17,000 people died in driving accidents in Iran, which about 3,300 of them were motorcycles' passengers. Also, intersections all over the world include a major share of accidents. Therefore, due to the increase in the use of motorcycles in the world and their low safety level, It is important to study the impact of various variables on safety of motorcyles at intrsections. Among the variables, the movement speed is particularly important due to its direct relationship with the severity of injuries caused by accidents. In this study, which was conducted by video analysis method, A total of 304 conflicts between vehicles and motorcycles were investigated at intersections in Qom. Then, using one-way ANOVA analysis, an attempt was made to evaluate the effect of road users' movement speed on the safety of motorcyclists in conflict with vehicles at urban intersections, based on TTC and PET conflict indicators. For this purpose, Conflict indicators were investigated in two critical and non-critical states. As a result the value of vehicle's speed has a significant effect on making a conflict critical, so that it was 13 and 25 percent higher than the similar values in the non-critical states of TTC and PET indicators, respectively. while the amount of motorcycles speed did not show significant change in critical situations. It means that in conflicts between vehicles and motorcycles at intersections, among the different road users' speed, the main factor that makes a conflict critical and results in accidents, is the increase in the vehicles' speed not the motorcycles' speed. Therefore, proper safety measures to reduce the speed of these vehicles at intersections such as the use of intelligent speed adaptation systems or infrastructure measures such as visual signs or speed bumps are priorities.

Roundabouts usually have higher traffic safety compared to other types of intersections. Despite the transformation of intersections into roundabouts, high-severity accidents still occur in them. Improving accident prediction models and their parameters can help prioritize action and reduce the cost of geometric modification. This research aims to investigate the geometric factors of severity and the number of accidents in the weaving section at these roundabouts. In this research, by using the accident statistics of six roundabouts located in Qom city, the influencing factors on the severity and number of accidents were investigated using the logit model and gene expression algorithm. The results showed that the width of the weaving section had the greatest impact on the occurrence of accidents compared to other geometrical variables of the roundabout. Also, the type of accidents in which there was a vulnerable user such as a bicycle and motorcycle greatly increased the probability of being injured in the accidents, on the other hand, the presence of unauthorized access to the circular carriageway of the roundabout increased the severity of accidents from damage to injuries.

Traffic accidents, as one of the most important threats to human beings, have shown themselves as a dangerous phenomenon. The impact of various factors on the incidence of accidents with different contributions has made it difficult to reduce the consequences of this unpleasant event in the safety analysis. Calibrated simulation models by taking into account the interaction effects of factors such as various behavioral characteristics of users in interaction with road have the potential to assess the safety performance of traffic facilities in different situations. Identifying the effective calibration parameters in simulation models due to their different impacts according to the purpose of the study as well as computational constraints is one of the essential steps in the calibration process. This study aims to provide a solution to identify the effective calibration parameters in the safety microscopic simulation model. For this purpose, 4 detectors located at the Mashhad-Sabzevar-Tehran route and vice versa with 23 accidents and 306 traffic records were selected as case studies and by deriving geometric information from available databases, the simulation model of the study area was built in the SUMO microscopic simulation software. By logically executing the simulation model on selected accidents, the effective calibration parameters in the car-following model, as well as the lane-changing model, were identified and by adjusting them in multiple scenarios, the simulation model in the case study routes was calibrated and validated with the use of the safety effective calibration target parameters such as Surrogate Safety Measures (SSMs). Among all the parameters of the simulation model, the global parameters of the normal distribution of permissible speed coefficient index with a mean and standard deviation of 0.95 and 0.10, respectively, and also local parameters of the cooperative, assertive and keep right lane-changing indexes were identified as effective.

Transportation safety is the most important criterion in the engineering design of roads. Rural roads pedestrian accidents statistics show that this type of accident is tremendously important. From the safety point of view drivers need to have a reasonable time window for hazard recognition, reaction initiation and execution. This means that the hazard has to be in sight from a distance longer than the minimum stopping sight distance. Nevertheless, if the road side configuration make the sight available for a very long distance, it’s the hazards characteristics which defines the visibility along with the drivers’ behavioral characteristics as a human. The hazard color and mobility are some of the most important hazard characteristics. In this research using some variables of hazard characteristics, a linear accident probability model was developed and the effect of these characteristics and their interactions was investigated. The use of driving simulator was in order to prepare a ceteris paribus laboratory condition. Randomly invited, the test takers were 80 over 18-years-old person who had a driver license. The simulated environment was a straight rout in a plain terrain in which the driver’s sight were not obstructed. Drivers encountered averagely 14 hazards in this road including some pedestrian crossing the road with black or white out-fit and some black or white rocks in the road. The rocks were modeled to enable the comparison between the effects of state of being mobile or fixed on accident likelihood. According to the findings of this research, speed has an increasing effect and the number of prior facing with hazards had a decreasing effect on the accident likelihood, although this effect was not so considerable. The hazards including pedestrians and rocks with black color was about 26% more likely to be involved in an accident in night time in comparison with the white ones. This likelihood is estimated to be about 2% less in day time.

Paying attention to the effective causes of pedestrian safety is one of the components of urban transportation. Non-signalized intersections are considered a place with having high levels of risk because of happening many different conflict situations between vehicles and pedestrians. In this paper, the variables which are influential on the pedestrian safety based on the Post Encroachment Time are assessed. Such an assessing is done by linear regression models. For this purpose, the data was extracted observing a non-signalized intersection in Tehran called Vesal Shirazi-Bozorgmehr. The results demonstrate that the variables such as the vehicle, being a taxi and the pedestrians having unusual stops are effective in PET, having coefficients -0/08 and 0/38 respectively in 95 percent of reliability. Also, the number of pedestrians and vehicle's previous conflicts with other vehicles in the physical area of the intersection are effective, having coefficients equal to 0/04 and -0/05 respectively in 90 percent of reliability.

In this study, Malayer in Hamedan route and vice versa using the accidents of 2011 to 2013 as part of the dynamic segmentation. The segments were analyzed from the standpoint of safety audits and with respect to risk of each safety audit segment. The criteria used in the ranking criteria such as the side of the road, obstacles, visibility, access, level roadway, pavement, signs and markings. Accident-prone parts of the dynamic segmentation method, the audit by three expert safety audit and to estimate the risk characteristics of each segment were taken from each plot were calculated. Review and validation of the risk of accidents index components provided by the Department of Urban & Road (Iran) Safety Commission showed that more than 60% compliance. The highest risk Hamedan, Malayer 60-60 segment (Known as Pir Mishan) and other segments with lower risk were prioritized.

The guide signs are of the most important equipment for the traffic management, and play important roles in the traffic control. In this paper, regulations regarding exit guide signs color combinations determined for Tehran as a role model for other cities in the field of urban management, were investigated. In the regulation provided by Deputy of Transportation and Traffic of Tehran Municipality being the leading regulation for guide signs design, the rules on exit signscolor combinations differ from regulation determined for other types of guide signs. Therefore, explaining four criteria related to the governing rules of exit guide signscolor combinations, and also, determining the weight of those criteria; the exist guide signs were taken under consideration. Finally, it was concluded that the criterion named coordination with international regulation had the highest weight (0. 48) considered as the most important parameter in defining the new regulation regarding the traffic guide signscombination color. On the other hand, aesthetics criterion had the lowest weight (0. 041) known as the least important criterion. These all highlight the importance of scrutinizing other regulations published in the field of guide sign design. Also, it was concluded that the location of guide signs determined their color combination, especially the ones used as exit signs. Finally lack of consistency in the regulation regarding exit guide signs design in Iran was the most important outcomes which must be taken into account. In doing so, a number of suggestion were provided at the end of the paper regarding tackling these problems.

Pedestrians are subjected to high levels of risk at non-signalized intersections. Pedestrians at these intersections have conflicts with different types of vehicles such as motorcycles and cars. In this paper, pedestrian safety is compared between those two groups of vehicles using Time to Collision (TTC) as well as the Post Encroachment Time (PET). Data were collected from an intersection called Vesal-Bozorgmehr in Tehran. The one-way ANOVA was used to compare those two groups. The number of observations for each TTC and PET being the dependent variable was 758 and 791 respectively. Analyses indicated that LogTTC in conflicts between vehicles and pedestrians is 0.03 units more than conflicts between motorcycles and pedestrians and LogPET in conflicts between vehicles and pedestrians is 0.09 units lower than conflicts between motorcycles and pedestrians. TTC is used for identification of situations being potentially dangerous for pedestrians and PET is used for identification of critical situations for pedestrians. As TTC for the conflicts between pedestrians and vehicles is lower than that of for pedestrians and vehicles, motorcycles potentially cause more dangerous situations for pedestrians whereas when it comes to PET, vehicles have lower PET than motorcycles, so vehicles are more able to make critical situations for pedestrians.

One of the most important parts of the driver reaction is detecting hazard in prominent time. A hazard is detected in the right time if it is completely visible for the driver. There are various hazard types such as fixed obstacles, pedestrians, and animals that some of them cross the road. Right-time hazard detection and the post-reaction is of high importance in accident prevention. It is assumed, in this paper, that increasing crossing speed of hazards affects the driver's hazard detection. Different driver types including novice, low-experienced, and experienced drivers are chosen and various environmental scenarios are also designed. The eventual suggested model is Fuzzy Sugeno that estimates relation between the driver's detection score and the hazards' crossing speed. The results show that hazards' crossing and also increased crossing speed raises drivers' detection score and decreases reaction time. The increasing slope of the drivers' detection score diagram in relation with hazards' crossing speed in different conditions is 2% to 50%. The results are useful in training and hazard perception and detection tests, especially, for novice drivers and also, in making fixed and low-speed crossing hazards recognizable.

The low level of safety of transportation causes expanding social and economic consequences. It's also an obstacle to sustainable development. The pedestrian safety is one of the most important issues in the safety of transportation. Non-signalized intersections are one of the places in which there is too much risk for pedestrians because there are rarely any control equipment for pedestrians and vehicles movements. Therefore many conflicts between these two parties occur at such a place. Many effective variables on the intensity of conflicts have been identified, but many of them have been analyzed in signalized intersections and special types of movements like left-turn or right-turn. In this research, the effects of the type of movements (left-turn, right-turn or straight) on pedestrian safety at non-signalized intersections are analyzed using surrogate safety measures. The data have been obtained, using the image processing method. The effects of types of movement on Time to Collision (TTC), Gap Time (GT) and the Post Encroachment Time (PET) have been analyzed by one way ANOVA. The intersection is called Vesal Shirazi-Bozorgmeg Street. Finally, after analysis, it was realized that the type of vehicle movement is significant in only PET in the 95 percent of reliability. The significant difference exists between straight and right-turn movements. This difference was around 0.08 for the logarithm of PET. This measure was smaller in straight movements in comparison with right-turn movements because the speed of vehicles which move straight was more than right-turn ones and there was an indirect relation between the vehicle speed and PET.  

Traffic accidents on Iran’s road networks cause thousands of deaths and injuries every year, and cost the country’s economy billions of dollars. An intersection is a planned point of conflict in the roadway system. With different crossing and entering movements by both drivers and pedestrians, an intersection is one of the most complex traffic situations that motorists encounter. In small areas such as intersections, especially in resolution of maneuvers, identification of hazardous situations is impossible by using accident data for reasons such as the low occurrence of accidents and not specifying the exact location of the accident event. Therefore, in this study has been used the traffic conflict which were obtained from video analyzing. By using Time-to-collision (TTC) indicator and traffic volume, risk zone have been identified. As a case study, four leg unsignalized intersection located at the crossroad of Vessaleshirazi-Bozorgmehr in Tehran was chosen. The evaluation results showed that zone 3 is dangerous zone. The risk of zone 3 was 402.95 that was about 6.8 times the average risk of intersection. This conflict was the main reason for the increasing of the intersection risk.

Low volume local rural roads in Iran constitute 83 percent of countries’ roads network which have high initial construction and maintenance costs. Due to the specific topographic situation and low traffic volume (less than 400 vehicles per hour), most of these rural local roads do not need two lanes with the usual needed roadway width. Instead with a one lane two way specifications equipped with turnouts in determined spacing, these roads could have commensurate performance with their specific movement that also have acceptable traffic attributes. The most remarkable factor in these roads is minimizing the cars’ delays due to their stoppage in turnouts. For modeling one lane two ways roads equipped with intelligent transportation systems, computer simulation for modeling this type of road and performing related movement regulations have been used in this research. With the output results of the simulation process, regression model of turnouts spacing have been developed and the models’ parameters were statistically tested. Minimum delay for maximum road capacity with respect to determined values of turnouts spacing, total road length, permissible speed and turnouts capacity was calculated. In all different designated situations, minimum delay for maximum road capacity with respect to Poisson distribution of arrived vehicles number to the left and right origin in equal time intervals was 8 minutes. According to the results of this research increasing the turnouts spacing for one kilometer can reduce delay time for about 12 minutes.

With the increasing population and with the increasing demand for transport, State Highway Network developed, and traffic equipment for increase their safety in more feel. One of the most important equipment that related to road safety is guide signs. So For this purpose, the guide signs must have the best performance. Therefore , To assess legibility of guide signs, in this study , after designed two series of Guide Signs ; that the first series and a second series consists of 21 signs and 28 signs were ; By using software DMDX , with regard to conditions , Perception-Reaction Time (PRT) of Reading Signs Registered by users and saved in the system . Finally, with regard to restrictions on the viewing angle and the factors affecting it, the final model is the minimum distance legibility of guide signs is based on the volume of information presented.

One of our city streets and roads safety problem is the motorcycle-involved accidents. Researches have showed that about 20percent of road accidents is involved with motorcycles. Moreover, one of the most effective measures to reduce the motorcycle-involved accidents and improve the road safety is “education” and “riding skills training”. Nowadays, modern technologies like motorcycle riding simulators are used to take control of the 14 percent of worldwide accident fatalities caused by inadequate motorcycle riding skills training. In This paper, in order to take advantage of this technology for riding skills training in Iran, the major causes of accidents and law violation of motorcyclists of Iran was investigated. Firstly, 8 skill topic of training program was distinguished. Afterwards, using the similarity to the Ideal solution method, these topics was prioritized. Eventually, the resultant first three priorities were 1) yield right at intersections, 2) concentration and attention to forward, and 3) the use of safety apparatus- not to mention that other topics should be considered in training program with less hours of training and less priorities.

Road accident is one of the most important factors which are treating the country general safety and it is a real national disaster. Statistics show that despite of different indicators, the traffic accident risk’s and its casualties are in high level. In driving accident pedestrians have the less immunity therefore it is the cause of the most damage then allocated the most percentage of damage and injury. One of the most important factors in traffic engineering is pedestrian crossing safety. Investigating the parameters affecting the pedestrian’s safety margins and their relationship on the identifying the main causes of accidents relate to pedestrians on the streets without the traffic signs and driving has an important role. Although the raise of vehicle use growth rate in Iran has become an unavoidable issue and every day urban activities as pedestrians are accounted as one of most necessary parts of modern days life, numerous challenges in regard with decreased speed and mobility of urban traffic flow in contact with pedestrian users are readily imaginable. Speed and mobility increase are counted as urban traffic management goals. On the other hand this speed increase causes an increase in hazard index at vehicle and pedestrian conflict points. Use of traffic signs is a solution to enhance the drivers’ caution, the performance of which depends upon a variety factors such as cultural, human, infrastructure of road and behavior of drivers and pedestrians factors. For this purpose, 69 hours videos were recorded in 13 days, were evaluated. This study was cross - sectional and conducted on the basis of observational data. Data analysis was performed using STATA 12 software and linear regression method.
In this research, using voice message signs before the pedestrian crossing place marked by ladder road horizontal signs as the crossing place and sending the voice message alarm of approaching the pedestrian crossing place on 4 different frequency channels on FM waves, the attempt was to draw incoming drivers’ attention to this situations causing a decries in number of conflicts and an increase in safety using a voice sign so that the vehicles receiver play the message for the driver. This research is based on use of traffic conflicts indexes, more precisely the Time to Collusion index (TTC). To do this, the data of conflicts was gathered using an automatic video data excavating system, analyzing videos from three different points in the city of Qom, Iran before and after using the voice message sign. The first point was near the Valieasr Hospital along with Jomhuri Eslami BLVD. The second point was also along with Jomhuri Eslami BLVD near the Basij square and the third point was along with the Shahid Navab Safavi BLVD near the Abal-Basir high school. In this research, after capturing videos from study points in both situations of usual traffic flow and traffic flow being sent the warning voice message, condition of vehicle-pedestrian conflict TTC index was evaluated. The models results showed that the use of voice sign decreases the overall conflicts by 10%, the critical conflicts by 26% and increases the time to collusion by 0.124 seconds

Decrease in traffic speed will result in freeway’s passing capacity, and this means decrease in performance level of service quality. Factors resulting in traffic speed decrease are categorized as permanent or temporary. Raining parse is one of temporary factors decreasing free flow speed. In this research effect of weather conditions (rainy weather) are surveyed as a temporary cause of decrease in capacity of freeway and on freeway’s free flow speed in Tehran-Qom freeway. So it can calculate the rain fall decrement index in the geographic region of Iran, (previously not calculated). If the time of traffic considered in design of freeway in the time of rain, by using decrement index the design capacity can be optimized.
In this research. In the beginning rainy hour and non-rainy hour were identified and separated, and also hours with less than 0.01 millimeter of rainfall due to insignificant effects were ruled out and considered as non-rainy hour .Studies show that light rain has no significant effect on flow speed and capacity and in some points its effects are neglected. But in case of heavy rainfall due to decrease in driver's vision range and decrease in surface friction between vehicle's wheels and road surface, flow speed will be significantly less than light rain situation and the changes between free flow speed of in 2 different conditions , rainy hour and sunny hour would be calculated. And with use of multi regression analysis and validating data from statistics test, result would be evaluated. traffic data and weather data from the last 6 months of hijri shamsi year 1391 in Tehran - Qom freeway was gathered and results obtained also confirms that rainy weather will result in 3.5 to 8.9 % decrease in capacity and 4 to 10% decrease in free flow speed.

Skid resistance characteristics of road marking materials affect road safety appreciably. The two componenet road marking materials that are extensively used in pedestrian crossings should have skid resistance properties in order to assure safety of both pedestrians and cyclists. In this research evaluation of skid resistance and other physical properties of a two-component road marking material (that is extensively used in Tehran), were determined. Several mineral additives were used, namely Waste Glass, Silica and Leka (an expanded clay). British pendulum testing was conducted on all the samples and their skid resistance values (SRV) were determined. In addition to skid resistance, abrasion resistance, reflectivity and also adhesive properties of the samples were determined.Testing results showed that conventional road marking materials had poor skid resistance characteristics. With using the above mentioned additives the problem could be partially solved. Comparing the results it was shown that among the various additives, waste glass had performed better. In fact, the results showed that application of %10 waste glass resulted in SRV increase from 21 to 40. This also reduced abrasion resistance of the road marking material for some 10 percent and provided greater reflectivity.