فهرست مطالب

Transportation Engineering - Volume:6 Issue: 2, Autumn 2018

International Journal of Transportation Engineering
Volume:6 Issue: 2, Autumn 2018

  • تاریخ انتشار: 1397/02/13
  • تعداد عناوین: 6
|
  • Ali Nazarinasab, Mojtaba Ghasemi *, Seyed Morteza Marandi Pages 99-110
    In recent decades, porous asphalt has been extended for surface drainage in various regions throughout the world. The permeability of porous asphalt has an important role in the performance of asphalt pavements in the rainy weather. The most remarkable problem related to the porous asphalt is its short service time. Considerable efforts have been made to enhance the mechanical properties of porous asphalt. Steel slag produced from manufacturing processes is a by-product commonly deposited in landfills and thus results in many serious environmental problems. Very high amounts of steel slag is produced in Iran and if these waste materials could be well put into practical uses, it would decrease the burden on the environment. This paper presents a series of tests on modified bitumen and porous asphalt with steel slag powder (SSP) and crumb rubber (CR). Reference tests were also conducted on control bitumen and porous asphalt. The material properties for different types of bitumen and porous asphalt were evaluated by penetration degree, softening point, ductility, Marshall stability, indirect tensile strength (ITS), porosity, and permeability. The results of current research demonstrated that it was feasible to replace partial CR with SSP. SSP can not only increase the softening point and ductility, but also reduce the penetration degree. Compared with the control porous asphalt, the modified porous asphalt with SSP/CR had higher Marshall stability, Marshall quotient (MQ), ITS and porosity. When 90% of CR was replaced by SSP in porous asphalt, highest permeability was observed. From these results, it was concluded that SSP can potentially be used as modifier replacement in the production of modified porous asphalt.
    Keywords: Bitumen Modification, crumb rubber, Steel Slag Powder, Porous Asphalt
  • Hessam Arefkhani, Ali Tavakoli Kashani * Pages 111-122
    This study aimed at indexing crash worthiness capability of 20 most frequently used car brands in Iran. Since rollover crashes are one of the most important crash types due to their high impact on crash severity, they were chosen as the case study of the current research. In this regard, the data of 42,118 rollover crashes of urban and rural roads of Iran which occurred from 2009 to 2012 was used. Binomial Logistic Regression Model was applied in order to define crash worthiness index based on the driver’s injury status. Although the results revealed that Proton and Hyundai/Light truck had the best performances in rollover crashes, no special trend was found regarding to crash worthiness capability of foreign and Iranian brands. The results of motorcycle rollover crashes were also included for model validation.
    Keywords: Rollover crashes, crash worthiness, binomial logistic regression model, vehicle brand, Iranian car brands
  • Mahmoud Shafiepour, Mohammad Tamannaei *, Mahdi Abtahi Pages 123-143
    This study aims to develop a novel methodology to prioritize the construction of new railway infrastructures for privatization. The private sector can cooperate to solve the capacity problems of railway networks, by the construction of new infrastructure. The purpose of this study is to answer the basic question that whether the capacity problems of the railway networks can be solved simply by building the new infrastructures without capacity improvement solutions, or not. Another main question is that which of the new construction projects are more prioritized to be built. The main contribution of this paper is to propose a new methodology to answer the mentioned questions, based on railway capacity, traffic assignment and calculation of Net Present Value (NPV) indicator. To evaluate the proposed methodology, Iranian railway network is considered. The NPV indicator is calculated for a 30-year duration, considering both direct and indirect benefits (benefits resulting from reduced accidents, reduced environmental pollutants, and fuel saving). The results show that building of new infrastructures, simultaneously with improving the capacity of the existing railways can lead to superior efficiency, compared to merely building new infrastructures. For the cases of building the construction projects without and with improving the existing railways, the values of maximum NPV were 88.1 and 221 thousand billion rials, respectively. Also, the values of absorbed demand were 52.18 and 46.72 million tons for two cases, respectively. The proposed methodology and the results of this study can be used as a practical tool for railway management to identify the priority of different construction projects of new infrastructures.
    Keywords: Railway Transportation, Capacity bottlenecks, infrastructure construction, private sector, Traffic Assignment
  • Peyman Mohseni, Amin Mirza Boroujerdian * Pages 145-156
    Accurate estimation of saturation flow rate is a prerequisite for accurate estimation of level of service and delays of signalized intersections. Saturation flow rate of intersections depends on many factors, including traffic behavior and culture. One of the important problems of traffic behavior in Iran is the violation of law at the physical region of intersections. The main purpose of this paper is to study the effects of violations such as pedestrians and motorcyclists ignoring the red light and vehicles changing their lanes at the physical region of intersections on the saturation flow rate.
    The raw data was gathered through monitoring from 100 cycles of traffic light at Valiasr-Taleghani intersection in city of Tehran during evening peak hours and extracting about 3000 headways. The study is based on the use of linear and nonlinear regression models. The results show that user’s violations affect saturation flow rate; one unit increase in the traffic light violations by motorcyclists (per hour) leads to 0.66 unit decrease in the saturation flow rate, and one unit increase in the violations by pedestrians passing the crosswalk near the intersection entrance reduced the saturation flow rate by 0.43. The non-linear regression model was used to estimate the coefficients for each of the violations and to adjust the base saturation flow rate values suggested by the highway capacity manual.
    Keywords: Saturation flow rate, Intersection capacity, Traffic behavior, User's violations
  • Mohammadsina Semnarshad, Mahmoud Saffarzadeh* Pages 157-176
    Rapid growth in a number of vehicles on roadways accelerates pavement deterioration trends. Pavement inefficiency in carrying the applied load from passing vehicles results in spending significant costs on continues Maintenance and Rehabilitation (M&R) treatments. Lane closure owing to the implementation of M&R operations incurs enormous costs on road users. The research aimed to calculate, and compare Road Agency Costs (RACs) with Road User Costs (RUCs) resulted from certain types of M&R interventions on a selected roads network located in eastern part of Iran. RUCs are divided into two main categories; namely, Vehicles Operational Cost (VOC) and Travel Time Cost (TTC). The main contribution of the paper was to demonstrate the importance of RUCs in long-term economic analysis and planning of future M&R activities. A number of complicated parameters are involved in RUC estimation. The latter is the primary reason for excluding RUCs in the economic analysis. Towards this end, the HDM-4 Software was employed to calculate costs using localized data. Calibrating the HDM-4 as well as collecting the required information, the long-term effects of preservation alternatives associated with their costs were evaluated and compared. Results showed that RUCs were approximately 10 times higher than RACs on each route of the selected roads network. This revealed the importance of RUC in the Life Cycle Cost Analysis (LLCA) of different M&R actions tale place on highways. Hence, taking into account RUCs within analysis approaches would yield propose the most appropriate and cost-effective M&R alternative. Also, it was concluded that traffic composition and the number of Equivalent Single Axle Loads (ESALs) in the analysis period were contributing factors to RUCs calculation. In addition, owing to the long queue formation because of road obstruction, VOCs were always higher than increased TTCs, illustrating the importance of traffic volume and composition.
    Keywords: Road user costs, HDM, 4 Software, life cycle cost analysis, Maintenance, rehabilitation
  • Ahmad Goli *, Mohsen Aboutalebi Isfahani, Amir Amini, Ali Latifi Pages 177-189
    The use of polymer in hot mix asphalt production has remarkably in recent decades. Destruction due to moisture in hot mix asphalt is of basic matters about flexible pavement durability. In recent decades different ways have been used to evaluate moisture Sensitivity of HMA which some of them are simple with low cost and some are complicated with more reliable results. In this research the effect of polymer Lucobit on striping was investigated and boiling test and image processing technic and modified Lottman test that is the most popular test for moisture sensitivity were executed. Marshall Test, indirect tensile strength and dynamic shear rheometer (DSR), were done as additional tests. The results show that use of this polymer has a remarkable positive effect on moisture sensitivity and has improved other parameters of bitumen and hot mix asphalt. The results showed that 2%, 4% and 6% Lucobit, by which the PG 58-** will be upgraded to PG 64-**, PG 70-** and PG 76-**, respectively. In addition, the addition of 6% Lucobit has led to improvement of high temperature performance by 14.7 ºC and enhancement of three grades from PG 58-** to PG76-**. Also, the addition of 6% Lucobit has led to enhancement complex modulus by an average of 53.7 %.
    Keywords: Moisture Sensitivity, hot mix asphalt, Polymer Lucobit, Stripping, Bitumen