فصلنامه مهندسی حمل و نقل
سال پنجم شماره 1 (پیاپی 17، پاییز 1392)

Nowadays، one of the most important challenges of the Iranian metropolitan areas is the problem of city’s interior transportation. Beside the recurrence of common investment in society’s infrastructure، lack of strategic planning for transportation of the city، causes disharmony and maladjustment of these systems and may result in numerous problems in sub-systems connections. Transportation control can be the most significant apprehension in management of The City of Mashhad. In the same issue، provision and development of persistent transportation can be an effective tool in leading city development، environment forming and promotion of city’s living quality. In this study، data collection procedure based on library and field studies (interviews and questionnaires) was done. At first، strengths and weaknesses، opportunities and threatens of the city’s persistent transportation were determined and then، they were analyzed using SWOT model. Finally، represented strategies were prioritized by exploitation of city planning quantitative matrices. The findings of this study prove that the end strategy in the development of persistent transportation of Mashhad metropolis is an aggressive strategy that is based on reinforcement of strengths and exploitation of opportunities.

Reduced transfer time results in increased levels of service to citizens and their satisfaction would increase consequently. To this end، using new and improved routing algorithms and localizing them in urban areas، considering their scope and extent، can be efficient in urban management and relief sectors. The purpose of this study is to look at the operation of the routing algorithms، including Genetic and Ant colony and due to the size of the city conduct a research to optimize the routing by using Game theory algorithm in the software ArcGis. Therefore، programs written for routing with Genetic algorithm، Ant colony and Game theory were called for in the software ArcGis and then used for routing. The results showed lack of spatial information database shared between rescue squads makes their services impossible in the least amount of time and if spatial databases are made and used، due to the small size of the city of Semnan، the time to achieve an optimal route by ArcGis using Game theory algorithm would be shorter compared with other algorithms. Therefore، the time for the Genetic theory، Game theory and Ant colony are 0. 27، 0. 23 and 0. 19 ms. respectively. Time to reach the crash site، using the routing by ArcGis program with Genetic algorithm، Ant colony and Game theory are 3 minutes and 5 seconds، 3 minutes and 15 seconds، and 2 minutes and 42 seconds، respectively.

Resilient modulus of asphalt concrete is one of the key input parameters in design of flexible pavements using mechanistic-empirical methods. Resilient modulus of asphalt mixes in laboratory is usually measured by applying a haversine pulse with a constant duration which could not be an actual simulation of stress pulse in field. In this paper، the effect of various parameters of loading pulse consisting of the shape، duration; the ratio of the pulse duration to rest period as well as the number of pre-conditioning cycles on the resilient modulus of asphalt concretes was investigated. For this purpose، complex modulus of four different asphalt mixes were utilized and after validating results of numerical method based on viscoelastic theory، resilient modulus of these mixes was computed under different conditions. Results of this research showed that the shape and duration of loading pulse affects the resilient modulus of asphalt concrete، significantly and these parameters should be considered in analysis and design of flexible pavements. In addition، the ratio of the loading duration to rest period must be equal to 9 or greater values to achieve the minimum accuracy of 3% in measurement of resilient modulus. In this paper، two models with high generalization ability have been presented to predict the resilient modulus of asphalt mixture with respect to loading duration and temperature. By taking advantage of these models، it is possible to carry out a limited number of resilient modulus tests and calibrate the model for the desired asphalt mix and then the resilient modulus of asphalt mix can be predicted in any temperature and loading frequency، accurately. It was also observed that there is a good relation between the resilient modulus under haversine pulse and resilient modulus under square pulse and after calibration of model in basis of limited number of experimental tests and known resilient modulus under Haversine pulse، the resilient modulus under square pulse can be predicted، accurately.

One way to increase the willingness to use public transport، is greater coordination and integration between modes in the network. Using mass rapid transit is justifying when appropriate demand of them are provided by lower level networks such as feeder network. In this paper، the effect of changes in demand on the design parameters of the multimodal feeder network has been analyzed. According to complexity of mathematic approaches to solve public network design problems، we used a meta heuristic method، Ant Colony Optimization algorithm. The results show an increase in demand in the suburban areas has more effects on the functional parameters to CBD areas and total cost of system would be increased. Because of multimodal services، this is made possible to short-turn services in the network until the variable lines frequency decreased the user and operator costs and increased utility of modes. In the current case study، reduced demand of near and far area from rail route causing to improve about 7% number of route، 20% frequency، 2% total route length and their headway is decreased about 21% to base scenario.

Rutting is one of the main distresses that occurs mostly in trafficked roads located in high climatic areas. The application of active fillers، such as hydrated lime، has been proved to increase durability and rutting resistance of asphalt mixes. Rutting resistance of a hot mix asphalt containing different percentages of hydrated lime (1، 1. 5 and 2%) and control hot mix asphalt (0% hydrated lime) has been investigated in this research. Marshall Quotient and Wheel Tracking parameters of these mixes were determined. Asphalt mix slabs at optimum binder contents were prepared at dimensions of 305×305×50 mm. The wheel track testing conditions of the samples consisted of the application of 1200 cycles of loading، which were applied at temperatures of 40 and 60º. Marshall Quotient tests which were applied at two temperatures of 45 and 60º. The results indicated that the addition of hydrated lime in mixes resulted in increased Marshall Quotient at two temperatures of 45 and 60º and reduced rate and rut depths at temperatures of 40 and 60º. The laboratory results of this research indicated that the addition of hydrated lime in mixes reduced rutting susceptibility of hot mix asphalt.

Recently، transportation planning has emphasized on methods that minimize costs of studies. Some researchers have introduced application of a model calibrated based on the data of city A، to a different city B. Although، one cannot expect perfect applicant of observations in the new city B، model transferability analysis can provide useful see sight. This paper introduces different forms and levels of transferability and also measures of transferability of mode choice models. A shopping trip in real scale at four levels of transferability is studied (transferring Tehran mode choice model to Qazvin). Morning peak shopping trips with three modes; private car، taxi and bus are studied، employing multinomial logit model. In order to set the ground for meaningful comparison of results، Tehran model structure was calibrated using Qazvin data. The model was discerned transferable at first، second and third level (except the variable of Central Business District) but not in fourth level. Transferability test statistics show inequality of variable coefficients for the two models at this level. Transfer Index analysis results the inappropriate of Tehran model applied for Qazvin due to lower goodness of fit measures. Moreover، relative error measures indicate relatively large difference between observed and predicted shares of different modes. Different social، economic and traffic condition and the effect of geographic terms and cultural manners on shopping trips would be part of reasons.

Providing a cost-effective solution to the two-fold problems of assigning locomotives to trains and train scheduling is of high importance for most railway companies. Due to high cost of deadheading locomotives and tardiness of trains، solving these two problems simultaneously has a significant impact on decreasing transport expenses in Iranian railways. The locomotive assignment problem is to assign locomotives to a set of freight rakes in order to provide the hauling of all freight rakes while maintaining minimum possible movements of deadheading locomotives and minimum coupling delay of freight rakes. In Iranian railways، passenger trains run across the network according to a fixed schedule. Scheduling freight trains is to determine the departure time، arrival time and the movement sequence of freight trains during the intervals between passenger trains in the way that they do not interfere with passenger trains’ schedule and at the same time minimum delay of freight trains occurs. In this paper the problems of locomotive assignment and train timetabling have been solved in two phases. In the first phase، locomotives are assigned to freight rakes using a genetic algorithm. In the second phase، the best locomotive assignment solution which is the output of the first phase is selected and a lower bound for arrival time of freight trains on their destination is calculated. Then freight trains are scheduled using another genetic algorithm. Using the applied method، the results of 30 test problems of simultaneous locomotive assignment and freight-train scheduling are presented.

Variables exist in the urban spatial organization، interact other variables of travelling modes of the citizens. Lack of planning process to analyze these variables increases the time، distance، costs and causes high use of private vehicle to access the functional locations of the city. Rasht is a broad city that its spread spatial organization has caused citizens to use other travelling modes than private cars. Thus appropriate distribution of the physical، social and economic elements into urban neighborhoods would be the objectives and requirements of an urban planning model. The main hypothesis of this research is finding a meaningful relationship between dispersion of the urban good shape variables and modes of traveling of the citizens to access to urban functions. The article aims to analyze the relationship between each of the good city variables and the local functions and its effects on the use of private cards. This research is an applied- development project conducted by a «survey» method. Statistical society of this study is the total citizens of Rasht city. The sample size was estimated to 382 persons by using the Morgan Table. Sampling method is cluster and in order to analyze data to determine significant relationships between variables the non-parametric، 2 variable Spearman has been used in the form two- dimensional tables in SPSS software. Research findings show that between the dispersion and lack of urban good shape variables and high levels use of private cars، there is a significant relationship. Also results indicate significant relationship between inappropriate distribution of commercial، recreational، educational and sports usages in the neighborhoods of Rasht، which shows a significant relationship، with frequency of inter- urban trips to access to urban functions and frequency of inter- urban trips to access to urban functions.

Compared to the past، derailment prevention for a majority of railway machineries is now a more important task. Crosswinds are amongst the reasons for the derailment of the railway vehicles. Combination of the moving train and the turbulent transient flow of air causes complexity in the air flow domain. This can expose the rail vehicle to sever instability and increases the oscillations in the resultant aerodynamic forces and momentums. Interaction between such loads and the vehicle dynamics can cause instability problems. This can eventually lead to the derailment of the vehicle. On the other hand، to comply with the never ending demand for increasing the speed of travel، lighter materials are used in the structure of the railway vehicles. Combination of the lightweight and the increased speed of travel adds to the anxiety about the stability of the train. Such anxieties amplify especially when the vehicle is subjected to crosswinds. This paper deals with the numerical simulation of the air flow surrounding the moving railway vehicle (Parsi coach) under the influence of crosswinds. Computational fluid dynamic engineering software is used. The aerodynamic forces and momentums for a variety of deviation angles and conditions of turbulence are calculated. The pattern for the flow of air around the vehicle and the pressure distribution on the vehicle surface are also calculated. Effects of the relative distance between the vehicles are also investigated. The most appropriate and practical distances between the vehicles are suggested. It is observed that doubling the speed of air that is directed at a yaw angle of 8 degrees، causes an increase of 4-45% in the corresponding aerodynamic coefficients.