فصلنامه مهندسی حمل و نقل
سال پنجم شماره 3 (پیاپی 19، بهار 1393)

Research show that adding clay to bitumen، improves bitumen performance. But uniformly distribution of clay particles in the molten bitumen is not an easy work. A simple solution for the incorporation of bitumen and clay particles is making clay-stabilized emulsions. On the other hand، chemical emulsifiers، is very expensive and the ability to make clay-stabilized emulsions in the country، with using domestic mineral resources، will be more and more useful and economical. Primary investigations showed that clay-stabilized emulsions production is mainly possible with using bentonite. In this study، domestic production bentonite was used for making emulsions. Clay-stabilized emulsions successfully produced and Functional tests such as Viscosity، Particle charge، Coating ability and Water resistance were performed on emulsions. Also cold mix asphalt samples was prepared with emulsions and was evaluated with indirect tensile test. The results showed that increasing the percentage of bentonite، improved residue and emulsion properties and increased tensile strength.

Geographic Information Systems have many capabilities for transportation systems management. The network capabilities of GIS such as shortest path computations are very useful for transportation management. Graph theory is the base of network analysis in GIS. The current method for conversion of a transportation network to a graph is modeling the stations as nodes and the paths between stations as edges. In this paper we have proposed a new method for translation of a transportation network to a graph by dual graph concepts. Dual graphs are presented for simplifying and solving of the original graph problems. In dual aspect the transportation lines are modeled by nodes and their relations are modeled by edges. The implemented case study showed that a bus transportation network with 5 bus lines could be translated to a graph with 5 nodes and 5 edges that could be very useful in many cases، specially in evaluation of transportation system. In continuous، we have explained the wavelet transform and its applications in evaluating and planning of transportation systems. Wavelet is a mathematical transform that could extract much useful information from a signal. For instance in an innovative task، we used the wavelet transform for extracting the moment precise number of needed vehicles in every transportation lines. The implemented case study illustrates the direct relation between number of required vehicles and the rate of traffic in a bus line.

Some of the most important aspects of network design include calculation of short circuits and temporary states of electrical networks. The conductors used in a network not only should handle nominal current of the network and supply voltage drops within acceptable limits، but should also have proper electrical and mechanical characteristics for enduring sparks and short circuit currents. Besides، the range of short-circuit current changes should be determined so that proper equipment (such as switchgears and …) which can endure short-circuit currents are selected for protecting the system and breaking current of a short circuit in time. In this regard، the highest amount of short-circuit current should be calculated. Therefore، in this dissertation، at first an AC railway system fed via auto transformers are introduced and then some techniques for calculating temporary short circuit conditions (including a numerical and a Laplace calculation method) are presented. Since a solution via Laplace is considered in this dissertation، all components of the AC electric railway system (including substations، overhead power lines، autotransformers) and the overhead network (including the 3 phase network and transmission lines) are modeled in form of Laplace. For this integrated system (AC electric railway system with its overhead power lines) a complete Matlab application، which can calculate temporary short circuit states، is developed. Some of outputs of the system comprise current and voltage of short-circuit in various parts of the network. In this dissertation، a sample research network is selected and temporary short circuit states and short circuit currents in various parts of the network are calculated.

Equivalency load factor is one of the most important factors in design of pavement، that shows the influence of traffic on pavement distress. This factor can be defined experimentally according to Asphalt Pavement Regulationd of Iran Roads (Publication 234) and the only concern in choice of the factor is the type of the axle (single، tandem and tridem) no matter whether wheels are single or dual. In this study equivalency load factor of heavy axle load mentioned in Asphalt Pavement Regulation of Iran Roads was determined based on two approaches: Strain and dissipated energy and according to the fatigue criterion and then compared to the equivalency load factors in AASHTO and Asphalt Institute regulation. 3D-Move program was used to analyze pavement sections (thin، medium، and thick) and in three vehicle speeds 10، 50 and 100 km/h at the bottom of the asphalt layer. The results showed that equivalency load factor of single axles with single wheels is independent of pavement thickness number، vehicle speed and applied method in calculation of this factor. Also، it was observed that equivalency load factor of single axle in the maximum distress method has the same quantities for both strain and dissipated energy method. In this research، equivalency load factor of single axle with dual wheels obtains less than one for single axle with single wheel with similar weight that it needs to pay attention to this matter in Asphalt Pavement Regulation of Iran Roads. Also، equivalency load factor of AASHTO and Asphalt Institute are less than the calculation values obtained in this study.

Nowadays، modeling methods by using petrinets in broad and complex networks، especially by developing computer science and the increasing the computers speed، has got a wide range of use. The graphic capability of petrinets has caused that these networks be utilized broadly in industry. In this study a closed rail-road network in which Normal and Express trains، by using petrinets can move has been considered as a model. By dint of analyzing the computerized model network، the total reachable space state that exists in rail-road network، has been drawn and the network will be analyzed from the point of view of Safety and Free dead-lock. By means of Supervisory control designed based on petrinets، not only it removes the dead-lock situation revised network، with the allowed number of Normal and Express trains، but also its safety would be guaranteed.

Nanomaterials have been used in the recent years in some projects، in order to enhance rheological properties of bitumen and mechanical properties of asphalt mixes. The Application of nanomaterials is limited mainly to laboratory studies due to the high price of these materials. In this paper، nano hydrated lime were produced by economic procedure (milling by satellite mill) at specified speed and time using Process Control Agent (PCA). The average particle size of hydrated lime reached from 760 nanometer to 281 nanometer as it was determined using SEM (Scanning Electron Microscopy) photos and Dynamic Light Scattering (DLS) graphs. The role of nano hydrated lime on mixes was compared with those containing nanoclay and hydrated lime. As for the optimum amount of the materials the addition of 5% nano hydrated lime (by weight of bitumen) and 2% nanoclay to bitumen resulted in 52% and 49% increase in Tensile Strength Ratio (TSR) respectively.

Urban environment quality is the issue taken into consideration in urban planning. Many issues may affect environmental quality، one of them is transportation. In this research، inner city rail transit and specifically Light Rail Transit (LRT) has been considered. Three dimensions define quality of urban environment; environmental، social، and physical-functional. Rail transportation can influence these dimensions in a positive or negative way. The present study intends to investigate the effects of startup line 1 of Mashhad LRT on urban environment quality in general and specifically in Taleghani، Parvin Etesami and Namayeshgah stations. Questionnaire، interview and observation are used in this study to gather the information. The results of the study reveal that the effects like increasing noise pollution due to surface rail (environmental)، making welfare and bliss view in citizens’ image (social)، and reinforcement physical structure of the city (physical-functional) are significant in the case study. However، the effects like reducing the rate of car ownership (environmental)، negative effects on local identity due to presence of strange people in neighborhood (social)، and raising the price of the land، consequently changing in land use (physical-functional) are not proved.

Nowadays، subways and urban tunnels are one of the most important infrastructures of public transportation network in big cities. Since the new tunnel projects should be constructed in under ground in populated urban areas، construction and implementation of this underground systems may cause damages to utilities، surface and subsurface structures. In this article، because of the importance of the issue of crossing the old urban areas and the need to reduce damages as much as possible، the distance between Stations N. 11 and 12 of Line 1 of Tabriz Subway that contains of old and traditional structure with old buildings of low strength has been studied. Due to existence of Cultural Heritage buildings in this distance، the study of settlements was performed using three different methods including Peck’s empirical method، Laganatan & Pollus’ analytical method and finite element method of numerical methods (using PlAXIS3D Tunnel software). Finally، the results of aforementioned methods were compared. The results show that the settlement values ​​obtained from the numerical model are more than the settlement values obtained from Peck’s empirical method and Laganatan & Pollus’ analytical method. Also، since the settlement values obtained from the numerical model are more than the allowable settlement values in urban and residential areas، it is needed to perform the necessary controlling strategies in this distance in order to make the excavating system able to cross this distance safely.