فصلنامه جاده
سال بیستم شماره 4 (پیاپی 73، زمستان 1391)

Structural Health Monitoring Systems (SHMSs) for possible use in new long span and critical bridges with emphasizing to the design issues, user safety and optimization of the maintenance process of the system are introduced. In order to achieve more convenient investment in the SHMSs it is require that a design philosophy focusing to the shape optimization of the system to be applied. This is achievable only when specific sensoring of the system with the purpose of full accessibility of the system associated with simple contact with users to be done in which, every information and alerts from each point of the structure is received, operated and processed. SHMSs are usually used as powerful and integrated tools for bridge maintenance management through updating models of the service life, maintenance programming and assignment of the repair budgets. Only with focus on the aim of this paper, i.e. maintenance optimization, it is possible to organize and economize every investment in the SHMSs with increasing in the user safety and structural maintenance performance.

In this paper characteristic of low-cost carriers such as fleet type, route of flight,booking system, service providing, pricing systems and ticket sale has been investigated.In next step, required infrastructures such as airports, laws and regulations and policiesgoverning low-cost airlines operation were identified. After investigating currentsituation of country, necessary changes for successful running of low cost carriersbusiness – model has been assessed. The guidelines include changes in strategies as wellas required activities to pave the way for operation of low cost carriers in Iran.

Bus transportation system is of the most important public transportation. Improvement of this system has a considerable effect on the efficiency of the urban transportation system as well as increasing passengers’ satisfaction and attraction. Consequently, this will result in energy saving and reduction in volume of traffic and environmental pollution. All the issues about bus network design including the optimal routing and the fleet size in each path are taken into account as a crucial issue in public transportation planning. These issues are so complicated that no exact solution can be found in real cases. This study attempts to introduce a method to find optimized path of the bus network in terms of passengers’ satisfaction through applying ant colony algorithm as a metaheuristic algorithm. The passengers’ satisfaction is assessed by an overall objective function which includes some desirable parameters such as the fulfilled (coverage of) demands, the path frequency, the network accessibility, the number of transfers and the traveled distance. In this paper, the Sioux-falls network is simulated in proposed model and the results are compared with the shortest path algorithm. The improvement in represented paths via proposed algorithm is remarkably evident compared with those from shortest path algorithm.

The importance of quality assessment from the users perspective, access to information about quality level of various parameters of transportation services from the perspective of their users and providing them to authorities with the aim of developing future policies and programs is along with responding user’s needs. Disadvantages and shortcomings of previous methods presented in this topic demands selection and presentation of a new, convenient and practical method necessity. In the method presented in this paper, an overall system reviews all aspects of service quality from the perspective of user in addition to its simplicity and practical. First, some affecting parameters on the quality of public transport services (bus) were selected, and then importance and performance of the desired parameters were measured from the perspective of different users by means of questionnaire. Finally an indicator of SQI (Service Quality Index) was designed and calculated in normal and BRT service in Tabriz city, to assess design services quality by combining importance and performance criteria with a scientific, systematic and accurate. It should be noted that totally 320 filled questionnaires had collected from users, after calculating SQI the value of 6.19 obtained for BRT services and 4.94 for normal bus services. Meanwhile except one parameter, in other parameters the value of quality in BRT services was much better than normal services. Results indicate the low level quality in normal and intermediate level quality in BRT service; then so necessarymeasures to improve conditions is absolutely necessary.

Damage Caused by moisture, one of the most important distresses in cold recycled flexible pavements. To overcome this problem, the materials that improve adhesion between aggregate and bitumen should use. In this research we used SBS polymer, cement and lime to improve adhesion between reclaimed aggregate pavement (RAP) and decrease moisture susceptibility. We used SBS for product polymeric bitumen emulsion and also cement and lime utilized as additive in recycled aggregate. Also, considering to type of aggregate, CSS-1 emulsion was used in this research. For evaluate moisture susceptibility of mixture, mechanical flooding and indirect tensile strength (ITS) carried out. Results from both tests demonstrate that SBS, cement and lime decrease moisture susceptibility and SBS role most effective in decreasing moisture susceptibility of RAP mixtures. It must note that best result was observed in specimens made with polymeric bitumen emulsion and cement.

The best way to reduce highway noise is predicting measures in order to reduce the noise at sound source place. This research is about the changes of traffic noise emission given by asphalt pavement over the time cause of traffics made by any vehicle types, according to accomplished observation the asphalt pavements noise level normally increases by its longevity. For porous pavements, it is a known phenomenon that the voids of the pavements tend to clog (compress) which leads to increase noise-generated from air compaction. But for other types of dense pavements or patulous graded one (not real porous) because of continuous changes in surface structure noticing atmospheric and traffic conditions in pavements life cycle the noise increases. Physical changes like raveling, cracking, etc are noted. That causes this increase in noise in the period in between when the bitumen film is warn off and when the pavements begins to deteriorate with distresses like raveling, cracking etc. The increase of noise has normally been analyzed in relation to the age of pavements. In this research this is supplemented by also using the traffic load as well as an artificial indicator defined as the change of noise predicted as a combination of actual physical age and traffic load.

Tunnel boring machine and precast concrete lining (segmental lining) are two main parameters (that) should have been considered for tunnel excavating specially. By considering that the segmental lining is not uniform ring, investigation and estimation the behaviour of segmental lining are complicated. First, in this paper, we have been tried to introduced, the usual methods of investigation in segmental lining, as follow: Elastic, “Schulze and Duddeck”, “Muir Wood”, “Beam-Spring” and Finite Element models. As Beam-Spring model is acceptable and comprehensible, so developing this method in different ways, has been discussed completely. As joint is main and important factor in lining behavior, so segmental joint has been studied and the method of calculation joint stiffness has been introduced by this paper. Finally, this paper has been tried to present modulation and maintenance of beam-spring models, by two case-studies.