International Journal of Transportation Engineering
Volume:7 Issue: 1, Summer 2019

This study considers a combination of cross-docking and vehicle routing problem (VRP) approaches to transport raw material and parts in a supply chain. The supply chain is composed of some suppliers which are spread in different geographical zones and multiple shared vehicles with different speeds and capacities for transporting orders from the suppliers to a manufacturer. After proposing a mathematical model of this new problem, a developed version of genetic algorithm based on a psychological theory, named Reference Group Genetic Algorithm (RGGA) is used to solve the problem. The originality of this research is proposing a new method in integrated production and transportation scheduling in supply chain by combination of cross-docking and VRP approaches, presenting the mathematical model of the problem and adapting RGGA to solve it. To evaluate RGGA performance, we develop a genetic algorithm proposed for the nearest problem in literature and compare these two algorithms. Moreover, RGGA results are compared with optimum solutions by some low size test problems. The result shows the good performance of RGGA.

Freight and passenger transport are two main functions of the infrastructure and transportation networks in each country. It is required to efficiently utilize the transportation infrastructures to increase transportation-related performance measures. In this study, data envelopment analysis (DEA) model is used to evaluate performance of the Iranian provinces from the freight and passenger transport perspectives. In this regard, transportation infrastructures such as roads, freeways, highways and arterial roads are considered as inputs to the provinces that are Decision Making Units (DMUs) in this research. Also ton-kilometers of the crossing freight, ton-kilometers from the province, passenger-kilometers of the crossing passengers and passenger-kilometers from the province are considered as the main performance measures of the provinces in the freight and passenger transportation. Two main efficiency-related indicators including Freight Transportation Efficiency Indexes (FTEI) and Passenger Transportation Efficiency Indexes (PTEI) are obtained to provide the possibility to assess efficiency of the provinces. The results are obtained to compare efficiency of the provinces from two freight and passenger transport. Results indicate that the Tehran province is efficient in three perspectives including “combined freight and passenger”, “freight” and “passenger”. Ilam province efficiently utilize transportation infrastructures for passenger transport. The Sistan, Qom, Kohgiluyeh and Hormozgān provinces efficiently utilize transportation infrastructures for freight transport. Transportation efficiency indexes for a number of the provinces such as Ardabil, Zanjan, Qazvin, Kermanshah, Golestan, Mazandaran and Hamadan are similar in freight and passenger perspectives. In addition, Alborz, Ilam, Khorasan Razavi, Semnan and Gilan have greater Passenger Transportation Efficiency Index (PTEI) relative to the Freight Transportation Efficiency Index (FTIE).

The purpose of Multi-modal Multi-criteria Personalized Route Planning (MMPRP) is to provide an optimal route between an origin-destination pair by considering weights of effective criteria in a way this route can be a combination of public and private modes of transportation. In this paper, the fuzzy analytical hierarchy process (fuzzy AHP) and the quantifier-guided ordered weighted averaging (Q-OWA) operators were integrated to calculate the weights of the criteria. Accordingly, a user determines the relative weights with fuzzy AHP method at first. Then, by considering his/her slightly decision strategy, the final weights (the ordered weights) were calculated and K-shortest route determined using K-shortest route algorithm. In the next step, the proposed model presented the best route to user using TOPSIS method. In this study, subway, BRT, bus, taxi, and walking transportation modes were considered for traveling. Also, time, fare, and minimum changes in mode of transportation were considered as effective criteria. This model is implemented in a web-based geographical information system for an area in the center of Tehran and results proved that on average 85.00% of the users with different decision strategies selected the route proposed by the model as the best route.

Study of various transportation indicators could be an appropriate criterion in evaluating the performance of the existing railways throughout the globe. This study was carried out to investigate the performance of rolling stock of Iranian railway using productivity analysis. In order to solve the problems, some solutions were provided by productivity management cycle steps. At the first step, it was tried to find how appropriate the rolling stock used in Iranian railway is. To evaluate productivity of rolling stock, data envelopment analysis method was used; besides railways specific indicators and partial indicators of rolling stock were measured. Consequently, during 1390-1394(2011-2015), the performance of rolling stocks was inefficient; however, rolling stocks were efficient in 1395(2016). At the next step, rolling stock productivity and its bottlenecks were analyzed according to railway performance, railway expert’s opinions, and previous studies. Questionnaires were answered by 20 experts. Cronbach's alpha reliability with measured value of 0.899 was proven. Productivity improvement strategies are extracted from the results of these analyses and will be used to prioritize on the basis of comparing the importance and the current situation.

In recent years, the value-added created in the transportation industry is about 8 percent of GDP of Iran. Due to the high-induced effect of transportation sector on the whole economy, analyzing transportation production function and its determinant is of great value for policymakers. The objective of the present research is to estimate the transportation production for the case of Iran and to examine the economic inputs of this sector using the auto-regressive distributed lags (ARDL) method based on time series of 1960 to 2014. The research results show, In long-term, the effect of capital, in comparison to energy input and labour, on the production of transportation services is quite stronger by production elasticity of 0.81 while labour and energy production elasticity is near 0.07 and 0.21. Based on the statistical test, the hypothesis of the existence of the economy of scale in transportation sector could not be rejected. Moreover, the coefficient of error correction term is equal to (-0.29), indicating a 29% adjustment toward equilibrium in each period, which It means, after imposing any shock in transportation production, it takes about three periods (years) to converge again to the long run trend.

Bridges built from any material and having any special shape will eventually show signs of wearing off; therefore, there are several factors in the kind and rate of such wearing off and its expansion such as atmosphere, flood, earthquake, overload, design quality, execution and kind of materials that will all reduce the functionality of the structures. Thus, maintaining processes and repairing the bridges may increase their life. In this article, after identifying effective risks on the bridges upon using them, critical risks are determined with FMEA method. After distinguishing the critical factors, each one is studied in details. Finally, three bridges in Bablosar (Iran), located over Babolrood River as well as their traffic role between the two sides of the city are investigated. Moreover, their roles on the traffic is also another case of interest in case with the destruction of any of these bridges, the communication to either side of the city faces serious problems. Also, the identified risks for each of these bridges are investigated to discern which of them is in no appropriate condition and if necessary they should be maintained and fortified. To do so, in this research by using AHP, ANP and Topsis Methods, these bridges are prioritized. Results show that the first bridge in this city has a worse state in comparison to the other ones and should be repaired, maintained, or fortified as soon as possible.