فصلنامه مهندسی حمل و نقل
سال دوم شماره 4 (پیاپی 8، تابستان 1390)

According to the figures issued by UNCTAD, containerized trade is forecasted to grow by an average annual rate of 5.32 percent between the years 2003 and 2025. This paper studies yard crane scheduling problem between different blocks for a container terminal. The purpose is to minimize the total travel time of the cranes among the blocks and also, the total delayed workload in each block at different time periods. In other words, the forecasted workload within each planning period, additional crane capacity or insufficient crane capacity for each block, the time when cranes should be deployed and the routes of crane movements, all should be determined in a way that satisfies our objectives. Therefore, the problem is formulated as a mixed integer programming (MIP) model. The block pairs between which yard cranes will be transferred during the various periods, are determined by this model. Afterwards, the model is coded by LINGO which uses branch and bound algorithm for solving. The results determine the yard crane movement sequences among the blocks to achieve minimum total travel time for cranes and minimum total delayed workload in blocks at different periods. The biggest portion of the objective function value, for example, with 13 blocks, eight of which lack carne capacity is related to the total travel time of the cranes within the blocks. It is caused by the slow motion of the yard cranes and their large size. Also, total delayed workload calculated for four problems, decreases over the six time periods until it becomes zero. In other words, yard cranes are deployed in an optimal manner. Also, the results show the efficiency of the developed program.

A choice to enhance public transportation service considers use of BRT lines. In this paper, a method for optimizing routes within an integrated transit network including BRT lines has been developed. A transit network optimization, including route structure and fleet optimization, can be based on minimizing vehicle transfers and total user cost while maximizing service coverage. The inputs of the problem are transit demand, transit fleet size and the street network in the area under study. Other information like BRT fleet size and number of BRT lines have been used to complete the study. As the first step in planning an integrated transit network, an estimate of the reduction in total travel time is needed. An optimization problem that uses Simulated Annealing and Fast Descent to optimize route structure and headway of transit network is considered. As a result, by solving an integrated transit network with one BRT line, user’s total travel time is reduced by 1.27, 1.54 and 1.43 percent for each case when BRT route time is reduced for 20%. BRT fleet change and using higher fleet capacity for BRT line reduced user travel time by 1.87, 1.80 and 1.81 percent in comparison to the transit network with BRT and the same bus and BRT fleet capacity.

Train derailments are unwanted and undesired incidents that happen frequently and disrupt the normal transportation operations. The extent of possible consequences and high occurrence rate of such an incident encouraged undertaking this research which aims at identification and evaluation of the causes and the potential consequences of the passenger train derailment. The integrated fault-tree/event-tree analysis (FETA) is usually applied for such purposes. Iran Railway provided the required data for this study. Due to inherent imprecisions and significant uncertainty of the available data, using the conventional FETA is not appropriate for this research. Therefore, the research has employed a fuzzy approach for fault-tree/event-tree analysis. A detailed modelling for the causes and the potential consequences of the train derailment is developed. The model is then quantified using a combination of available data and linguistic evaluations. Furthermore, to provide a better understanding, the model is evaluated to determine the contribution of different basic incidents, minimal cut-sets and scenarios to the risk and uncertainty of passenger train derailment. The modeling and the analysis presented in this research assist the decision maker to develop proper and practical solutions for reducing the risk through providing a detailed vision for the potential causes and the consequences of the train derailment.

Dowel action and aggregate interlocking are the main mechanisms for shear transfer at RC joints and cracks. Dowel action is the only transfer agent across precast joints like those in some kinds of RC pavements. Behavior of RC pavement is affected by the load transfer capability at the joint. Efficiency of such a structure is directly related to the transferred loads. Therefore, analyzing joint and crack performance in pavements has an important role and also depends on using proper behavioral models to simulate load transfer mechanism. In this paper, shear transfer mechanism through dowel bars in RC pavements has been investigated based on the beam on elastic foundation theory (BEF) and has been extended to beam on inelastic foundation (BIF) to take account of the nonlinear interaction between concrete and reinforcement bars. In fact, the main objective is to provide a method which significantly reduces the calculation and analysis time whilehaving acceptable accuracy. Model verification has been carried out in two parts (RC interfaces and RC pavements) in comparison with experimental results.

Following the fast development of rail transportation industry, great importance and need to study the Intelligent Transportation Systems for Iran railway domain is seen according to Iran’s strategic development plan. Signaling and control used in controlling and managing railway traffic in a safe and efficient manner plays the main role in intelligent rail transportation systems. Considering the high cost of purchasing, installing and maintaining signaling equipment, optimal selection of the systems according to the real requirements of the railway route is an important issue in saving the financial resources of the country and may prevent unnecessary expenditures. In this research work, Entropy Method, as one of the Multi Criteria Decision Making Methods, is used in selecting a suitable signaling and control system for Chabahar-Zahedan Railway route. Ten different signaling systems are indexed and 15 different criteria have been studied for an appropriate selection of the system. PROMETHEE and SAW methods are used for ranking. Finally, S3 system (traditional signaling, section block and automatic train protection) has been proposed as a suitable signaling system for Chabahar-Zahedan Railway.

Wheel and rail wear is an unavoidable phenomenon in railways. Several researchers have addressed minimizing wear rates. Compatibility between wheel and rail profiles is one of the significant parameters. Three main types of rail profiles including U33, R50 and UIC60 inclined at 1/20 have been used for Iran railway tracks. In this paper, these three profiles have been analyzed upon their interaction with wheel profile S1002. Effect of rail gauge, curve negotiation ability diagrams, equivalent coincity diagrams, rail inclination and contact area have been considered. Unfortunately, research results on the wheelset of profile S1002 and the above three rails in Iran shows an inconsistency causing high effect on wheel and rail wear. Consistency between U33 and wheel profile S1002 has been better than the other two tracks. However, even in this case, the interaction has been very sensitive to the changes in rail gauge and inclination. Tracks with UIC60 rail inclined at 1/20 have had the worst conditions for wheel profile S1002. Therefore, Iran wheel profiles must be improved and converted for better operation.

For making decisions in optimizing investments in road safety projects, it is required to establish a regular process for selecting the most suitable countermeasures to be provided to road safety planners and decision-makers. Using the model developed in this research, a given budget funded from the road agency may be distributed among all predetermined locations (sites or routes), considering: (1) applying the share assigned to each location, the best possible improvements are selected as the premiere strategy amongst all alternatives through which the highest benefit is resulted, and finally, the sum of net benefits for all locations is maximized, and (2) the sum of construction costs attributed to selected alternatives in all locations does not exceed the total project budget. A set of road safety measures is studied involving the items known as geometric features and road design criteria. The features defined here consists of lane width and road surface quality, roadside hazard zones, horizontal curves, crest vertical curves and narrow bridges. The cost-benefit analysis and binary integer programming methods are used to develop economic appraisal and complete optimization tasks. The Solver program (as an add-in to Excel) is the main tool to run the allocating process. The research economic appraisal and optimization process consist of eight steps within which some criteria are applied to define, valuate, discount and compare the cost and benefit components of the analysis. The most important measure to estimate the safety benefits is a mediator variable which is broadly known as Accident Modification Factor (AMF). In this research, AMFs are extracted for each geometric feature mentioned above using the current valid accident models in Iran. As a means to support the execution of the developed model, a software program contributing to running the process of resource allocation is provided.