International Journal of Transportation Engineering
Volume:5 Issue: 4, Spring 2018

One of the risks recognized by relevant authorities is the risk of outsourcing ITS projects. The purpose of this study was to design and explain the pattern of determining the critical success factors in outsourcing large-scale ITS projects in the Ministry of Roads and Urban Development (Road Maintenance and Transportation Organization). This study was performed using qualitative method. The participants in the research were the ITS experts experienced in large-scale projects, 25 of whom were selected purposefully as the sample. Theoretical coding method was used to analyze the information obtained by having experts’ opinion. The method included open coding and axial coding. The paper aims to develop a local model to recognize vital factors in outsourcing of large-scale ITS projects with regard to social and cultural characteristics of relevant organizations in Iran. Using in-depth interview with experts in relevant filed, a model was developed. The results obtained by theoretical coding methods showed that the critical success factors in outsourcing large-scale ITS projects in the Ministry of Roads and Urban Development are organizational factors, management factors, environmental factors and individual factors. Each of these factors includes a number of sub-sections that can be taken into account particularly. This local pattern can be applied for determining the critical factors in the Ministry of Roads and Urban Development (Road Maintenance and Transportation Organization). In addition to this, its outputs, including critical success factors and prioritization and preparation of outsourcing large-scale ITS projects can be exploited by the senior managers of the executive agencies for more accurate and consistent planning. The latter would prevent waste of resources and treasury.

Vehicle Routing Problem (VRP) is addressed to a class of problems for determining a set of vehicle routes, in which each vehicle departs from a given depot, serves a given set of customers, and returns back to the same depot. On the other hand, simultaneous delivery and pickup problems have drawn much attention in the past few years due to its high usage in real world cases. This study, therefore, considered a Vehicle Routing Problem with Time Windows and Simultaneous Delivery and Pickup (VRPTWSDP) and formulated it into a mixed binary integer programming. Due to the NP-hard nature of this problem, we proposed a variant of Particle Swarm Optimization (PSO) to solve VRPTWSDP. Moreover, in this paper we improve the basic PSO approach to solve the several variants of VRP including Vehicle Routing Problem with Time Windows and Simultaneous Delivery and Pickup (VRPTWSDP), Vehicle Routing Problem with Time Windows (VRPTW), Capacitated Vehicle Routing Problem (CVRP) as well as Open Vehicle Routing Problem (OVRP). In proposed algorithm, called Improved Particle Swarm Optimization (IPSO), we use some removal and insertion techniques and also combine PSO with Simulated Annealing (SA) to improve the searching ability of PSO and maintain the diversity of solutions. It is worth mentioning that these algorithms help to achieve a trade-off between exploration and exploitation abilities and converge to the global solution. Finally, for evaluating and analyzing the proposed solution algorithm, extensive computational tests on a class of popular benchmark instances, clearly show the high effectiveness of the proposed solution algorithm.

In Portland Cement Concrete (PCC) pavement of the roads, dowels bar transfers vehicle loading to the unloaded slab. Load Transfer Efficiency (LTE) is used to evaluate dowel bars in PCC pavement. This parameter is defined as the vertical displacement ratio of the loaded slab versus the unloaded slab. In this study, the impact of effective factors (friction coefficient between dowel and concrete slab, wheel loading, dowel diameter and dowel spacing) on load transfer efficiency was studied with modeling by using the ABAQUS finite element software. The verification process was presented to increase confidence in model results and the response data from the numerical simulation agrees well with analytical solution. The results show that with increasing the friction coefficient between slab and dowel, load transfer efficiency increases but the failure of concrete around dowel bars was found to initiate at the face of joint. Furthermore, if strains remain in elastic range, increasing in wheel loading magnitude does not lead to reduce load transfer efficiency but dowel diameter or its spacing have an important role on load transfer by dowels.

Resilient modulus and California Bearing Ratio (CBR) in unbound granular materials are the key technical characteristics of layers in a flexible pavement design. Among the factors affecting these two parameters, the aggregate gradation is the most important. Using particle size distribution curve developed by AASHTO, together with other considerations mentioned in the related regulations have yielded desirable results in many cases. However, many roads loaded by heavy vehicles, for which all technical instructions of standard regulations were observed, have undergone deformations caused by subsidence of layers. According to the related technical documents, one hypothesis could be the proximity of aggregate gradation to the boundary areas. Therefore, the aim of this study was to determine the effect of changes in the scope of aggregation in the border areas on strength parameters. For this purpose, effects of aggregate grading variation on two types of aggregates, i.e. limestone and quartzite (as determined by AASHTO) were investigated using specific gravity, CBR, and resilient modulus tests. The results showed that, in the gradation boundaries determined by AASHTO, the difference between specific gravity values was insignificant. In the CBR and resilient modulus tests, however, there was a significant difference between test results in the upper and lower limits of gradation. In addition, gradation variation had a lower impact on resistance parameters in quartzite aggregate compared to limestone aggregate. Therefore, under special utilization conditions, materials with highest values of technical specifications should be used, since even materials whose technical specifications are in the standard range may not behave as expected in real world situations.

Traffic oscillation, stop and go traffic, is created by different reasons such as: sudden speed drop of leader vehicle. Stop and go traffic commonly is observed in congested freeways results in traffic oscillation. Many theories had been presented to define congestion traffic based on laws of physics such as: thermodynamics and fluid. But, these theories could not explain the complexity of driving responses in different situations of traffic especially in traffic jams. Unfortunately, because trajectories data are very scarce, our understanding of this type of oscillations in congested traffic is still limited. When the leader vehicle of a platoon drops speed, deceleration waves are released from downstream to upstream. Follower vehicles reacts different behavioral reactions based on personal characteristics. In this paper, behavioral patterns of follower driver were classified based on asymmetric microscopic driving behavior theory and traffic hysteresis in NGSIM trajectories. They were four patterns in deceleration phase and two patterns in acceleration phase. Then, two parameters of last deceleration wave leading to congestion, time and space parameters, τ and δ, were calculated based on Newell’s car following model. Time of two phases, stop and congestion phases, were identified based on follower vehicle trajectory. In order to calculate time of two phases, two points were identified: point of receiving stop wave leading to congestion and point of entering to congestion. Artificial neural network models were developed to analyze the relationship between the microscopic parameters and time of two phases. Analysis results present spacing difference of follower between stop and congestion phase based on under reaction-timid pattern and spacing difference of follower between deceleration and congestion phase based on over reaction-timid pattern and spacing of leader vehicle at the wave diffusion point are most effective parameters in stop time leading to congestion. One of the main practical applications of this paper can be the addressing one of the main problems of micro simulation soft wares (like Aimsun) due to behavioral patterns.

According to the forensic statistics, in Iran, 26 percent of those killed in traffic accidents are motorcyclists in recent years. Thus, it is necessary to investigate the causes of motorcycle accidents because of the high number of motorcyclist casualties. Motorcyclist's dangerous behaviors are among the causes of events that are discussed in this study. Traffic signs have the important role of traffic controller, and road surface marking is a tool for traffic separation and has a significant effect on driver's behaviors. The aim of this study is to investigate the effect of variables, including traffic conditions, motorcyclist's psychological conditions, and symptoms and function of traffic lights on the motorcyclist's dangerous behaviors. In this study, classification tree method is used to determine the effective factors in some motorcyclist's dangerous behaviors such as the amount of deviation from the center lane, lane changing, and running red lights. The classification tree is easy to understand and interpret because of the graphical display of results. The data classification tree is made based on the classification and regression tree algorithm (CRT) in this study. The data are collected from the 7 intersections in a city with the medium population by video-based observation method. Hand-held cameras randomly record the motorcyclist's motions and, then, these behaviors are investigated in the office by playing back the videos at slow motion. The obtained trees show that the variables of traffic volume have the greatest impact on the motorcyclist's diversion from the center lane and lane changing. Also, the clarity of the pavement marking is effective in reducing deviation from the middle lane by cyclists so that, in the streets with the line color contrast of more than 1.36, deviation from the center lane is reduced by 25 cm.