JOURNAL OF TRANSPORTATION RESEARCH
Year:2010 | Volume:7 | Issue:1 (22)|Papers Count:8

One of the main tools in strategic transportation planning is to use modeling methods for different modes of trip demand. In modeling interurban passenger trip demand, especially in trip creating models or demand direct models, usually 3 to 4 demand effective independent parameters have been classically selected and then different models are made and calibrated using mathematical methods. The process for selection of effective factors on trip demand is one of the most important components in trip demand modeling which has been considered by few researchers. Some alternatives inserted in the model simultaneously may have similar effects. Therefore presentation of a scientific method for selection of effective factors on trip demand (among different alternatives) would be significantly important in making trip demand model.In this paper, classic parameters that are effective on creation of bus trip demand in road transportation system may be counted as population in different provinces of the country, number of students in Iran universities studying in 28 provinces of the country, level of employment in each province, monthly per capita income of urban households in each province, value added by industrial workshops in each province, number of mobile subscribers in each province and number of beds in dwelling establishments per province. As well trip time (incoming and outgoing trip times) and trip expenses (freight charge) are considered as effective parameters on selection of trip modes by urban bus passenger in state road transportation system. In this paper the method for selection of effective factors on urban bus trip demand by passenger in the state network has been given by compilation of a step by step factor analysis model and its reliability has been expressed. Evaluation of the results from purposed factor analysis for selection of the factors effective on urban bus passenger trip demand in the country shows that 3 factors among 9 studied parameters can be extracted. Factors determined from the purposed factor analysis in this paper have been significant with 90% confidence in determination of dependant parameter. Conceptual interpretation of the main factors obtained from purposed factor analysis model have been compatible with fundamental concepts of effective factors on trip demand in engineering theoretical  discussions in transportation, so they may be used in interpretation of internal correlations of a set of demand effective alternatives. In this way, using main factors obtained from the purposed factor analysis the process for modeling urban bus passenger's trip demand in the country  can be accormplished by using the smallest determining concepts for explanation of the highest value and common variance in correlation matrix.

Bus transportation system is one of the most important systems in urban areas. Increasing user’s satisfaction and optimal usage of existent facilities without planning is impossible. Dwell time in bus stops is one of the parameters that affect the quality of plans in this system. By identifying the factors that affect on dwell time and forecasting this parameter, we can develop proper strategies to reduce dwell time and increase both in vehicle and waited passenger’s satisfaction.  In this paper, Tehran bus transportation system was studied and factors that can affect dwell time parameters were identified and alternatively some data about dwell time in this system were collected. The regression analysis to estimate the effects of some these factors such as number of alighted and boarded passengers in stops on dwell time parameter was used. Based on the collected data, the ability of some functions in previous studies was evaluated to forecast dwell time parameters and a new nonlinear function to forecast it was developed. By microscopic analyzing of stop process, a new discrete event simulation model based on Enterprise Dynamics software was designed. This model was used to evaluate the strategies that can improve dwell time and estimate the effects of other factors that were not found in the collected data in this case study. The results show the dwell time of buses in stops can be reduced about 23 percent by changing in payment fare system to electronic payment system. Also the authors found out that the place of stops in this system has not any effect on dwell time parameter or gender of passengers is not important to estimate duration of stopping in stations.

This study is aimed at evaluating the effects of pavement roughness and darkness on the free-flow speed in the freeways. In general, most of valid codes such as Highway Capacity Manual (HCM), do not consider the effect of pavement roughness and darkness on the free-flow speed, capacity and service level of roads. In order to determine the pavement roughness condition, international roughness index (IRI) measured by Road Surface Profiler (RSP), manufactured by Dynatest Company, has been employed. Moreover, the relevant data on the pavement roughness and free-flow speed of vehicles have been recorded in the light and dark points at 16 sections of a freeway with the length of 62 km. Speed Gun device, traffipatrol XR model, has been utilized to measure free flow speed. This device is capable to measure speed within more than one kilometer at days and nights.  In order to prevent the effects of speed controlling on the behavior of drivers, the device was located in places where were not in the horizon of drivers. The results of the current study indicated that the free flow speed can be explained by the linear-inverse model based on road roughness at significant level of 0.01. Besides, the sensitivity of free flow speed to the roughness in the darkness is lower than that in the lighting. Finally, in this study typical factors to modify the roughness condition and darkness in the equations of free flow speed in the HCM method are proposed.

Physical and mechanical properties of aggregates are major parameters to determine the utilization of aggregates in road pavement surfacing. There are different physical and mechanical standard tests - mainly experimental - that  evaluate aggregates. These tests describe different aspects  such as geometric characteristics, strength and durability of aggregates. The quality control of stone materials in service conditions are possible by some mechanical tests. Studies carried out on characteristics of road construction aggregates show that there is a significant relationship between physical and mechanical properties of aggregates. However, majority of  research works in this field have not exactly specified  the type of relationship. In this paper, to determine the relationship between aggregate characteristics and also to evaluate the correlation between these characteristics, samples of aggregates from different quarries including carbonate, sandstone and igneous rocks were collected. Then, some physical and mechanical laboratory tests including specific gravity, impact value, Los Angeles Abrasion Value, sodium sulfate soundness and Polished Stone Value (PSV) were carried out on selected aggregate samples. Data analysis shows that the impact value, significantly has a linear relationship with Los Angeles Abrasion Value. This relationship in the group consisting of igneous rocks and sandstone is stronger than other groups. Based on more assessments in this research work, regarding the relationship between the Polished Stone Value and other physical and mechanical parameters, it was found that, PSV with specific gravity has a linear relationship in igneous rocks family. Therefore, increasing the specific gravity will result in reduced polished stone value. In broader group of aggregates consisting of igneous rocks and sandstone, a linear relationship is established between the polished stone value and combination of specific gravity and sodium sulfate soundness.

Nowadays recycling technology is used in many branches of science e.g. road civil works. In this research, 162 specimens of mixtures were produced by Reclaimed Asphalt Pavement (RAP) made from cut old pavements. The Cold in-situ recycling (CIR) method with foam bitumen was applied. It is mentioned  that each specimen has a weight of approximately 1200 g. The final goal of this article is to represent an experimental study on  tensile strength, resilience module, the ability to tolerate the dry and saturate indirect tensile stress (ITSDry and ITSSat) and the tensile stress ratio (TSR) of these mixtures. For this purpose, 162 Marshal Samples were built and cured for the time period of 72 hours under temperature of 40, and then, these specimens were analyzed and tested with UTM14, to obtain their module of resilience, in the laboratory of Ministry of Road and Transportation. Moreover, the total number of the samples (162) was divided into 3 equal groups and Marshal Strength, ITSDry and ITSSat tests were performed for each group, including 54 specimens. The differences between the samples were the amounts of bitumen foam (%1,%2, & %3), percentage and type of additives or active fillers which include %0, %1 and %2 of every type of active filler, such as Portland cement type II, slaked lime, quick lime, oven slag, pozzolan, and rubber powder. The Granulation of the RAP and the temperature of bitumen were assumed to be constant. To finalize the issue, the results of the above- mentioned tests showed that through applying SPSS and MATLAB software and artificial neutral networks modeling, one can forecast these results. Also, with a sufficient accuracy, the effect of each additive with its specific percentage of foam bitumen on the strength parameters would be measurable.

Planning the bus transportation system is one of the most important phases in planning of public transportation systems. Such planning is quite difficult due to some inconsistent goals. For example we cannot expect paths that are planned for minimum travel time, maximum covering and access. In this connection, to obtain an optimal answer, many criteria must be considered. In this paper, a new model has been represented for planning of bus transportation systems. The recommended system takes benefit of GIS (Georaphical Information System) capabilities. This model is based on travel distribution matrix between urban blocks and have some major goals, such as the maximum number of people transferred by the system as well as the minimum travel time. The method for extraction of travel distribution matrix between urban blocks has been explained in this paper. After extraction of travel distribution matrix and its allocation to city roads we use GIS network capabilities for planning of bus lines is used. By this method one can do the planning of bus transportation paths with consideration of some major goals, simultaneously.

Grouted rock bolts are one of the most popular systems of support in underground mining and tunneling operations. These can be installed as passive or active pretensioned elements. Passive grouted rock bolts develop load as the rock mass deforms. However, the active types are preloaded before rock mass deformation. In order to improve bolting design, it is necessary to have a good understanding of interaction and behavior of rock bolts in deformed rock mass. This can be acquired through field monitoring, laboratory tests, numerical modeling and analytical studies. Application of the rock-support interaction concepts to the support system such as concrete linings, steel sets, and ungrouted rock bolts, can not be applied to the reinforcing elements such as grouted rock bolts or cables. This is because, they don’t act independently of rock mass and hence the deformations, which occur in both the rock mass and support system, cannot be separated. In other words, the reinforcing elements confine rock mass deformation and tunnel convergence via improving or conserving the overall its' properties from within the rock mass. Consequently, the use of rock mass reinforcing techniques such as fully-grouted bolts or cable has encountered many theoretical problems. In this paper after reviewing of the past studies conducted by Smart and Bischoff (1975), Grasso (1989), Indraratna and Kaiser (1990), Peila and Oreste (1995), Still (1989) in the field of grouted rock bolts, ssuming that grouted rockbolts increase internal pressure within a broken rock mass, and consideration of Hoek-Brown strength criterion for rock mass, and on the basis of strain softening behavior model, rock-support interaction concept and convergence confinement approach, analytical models are presented to simulate the interaction between radial passive and active grouted rockbolts with rock mass in tunneling design. In these methods, the equations of ground response curve which has been reinforced with passive and active grouted rock bolts are also derived for a circular underground excavation under hydrostatic stress field. The proposed models allow one to take into account the following specific conditions: The effect of the increasing spacing between bolts, the effect of the increasing pretension load in response curve. At the end, some examples solved with new analytical approaches and the results were found to be in close agreement with the FLAC results in a quantitative manner.The example results show that decreasing spacing between bolts is more effective than preloading them in confining tunnel convergence to allowable value. It is also considered that, preloading will be more effective if the spacing between bolts decrease. It should be noted that, due to algebraic complexity, it is not possible to obtain closed-form solution; therefore a computer program was prepared for solving the problem on the basis of numerical methods.

This paper presents a linear integer programming model for a capacitated backhaul vehicle routing problem with time window (CVRPBTW) that minimizes the fleet cost and total traveled or the duration of the tours. We consider a heterogeneous fixed fleet with a fixed number of vehicles for each type (class). It is shown that the presented model enables to establish routes to serve all given customers (i.e., nodes) by the minimum number of vehicles with the maximum capacity used and minimum duration. This model is solved by a hybrid simulated annealing (HSA) method, in which is able to find very good solutions in a reasonable amount of time. A number of test problems in a small and large size are solved, and the computational results are reported in this paper. We investigate the performance of the proposed method in a real case. The input data are collected from waste and garbage collection industries for specified areas in Tehran.