The Role of Road Widenings in Designing of Mass Public Transportation Systems in Mashhad

Today, transport planning is one of the important aspects of urban planning. In this regard, enhancement of the public transport systems and guiding the urban travels towards these systems has found a crucial role in traffic improvement, preventing capital waste and reaching to the sustainable cities. In Mashhad, two systems, namely Light Rail Transit (LRT) and Bus Rapid Transit (BRT) are defined as the main public transport systems. This research has down with the aim of effect explain of city detailed design texture streets downtown road widening on the process of public transport route designing. It should be noted that the mean of widening is not the rampant road widening but it is just road widening according to approved urban detailed designs. Theoretical foundations of research is theory of urban sustainability. The research method is descriptive-analytic. Research data is obtained from data bank of Mashhad transportation comprehensive studies by documentary study. The most part of zoning in the city of Mashhad mean divided the city to 253 traffic zones has used in order to increase the accuracy of study. The routes of the main public transport lines have re-designed using ant colony algorithm. The algorithm objective function includes variables of population, employment and the surface of trip attractive land uses and the main limitation have been defined as width of streets in two case, present situation and widening streets. So, two reform options of mass public transport systems have been produced. Then, the access index has been measured based on Hansen relation in case of two mentioned alternatives. The research hypothesis testing showed that the access index in case of alternative which achieved road widening is significantly higher than the other alternative. The research results explain importance of city detailed design road widening in view point of improving main public transport routes and increase their efficiency. According to traffic problems of central business districts of mega cities and the consequences of this include air pollution and etc. it is necessary to adopt policies to deal with these problems. One of these policies is transferring trips from private cars to public transportation which requires efficient, reliable transportation. Based on previous studies, the most important performance indicator for public transportation systems is the level of access to such systems. Increasing the level of access to the main public transportation network which will be achieved in the event of implementation of the expected road widening in the city center's detailed plan can increase the use of public transport and consequently use less than personal vehicles. So, though, on the basics of planning sustainable cities, road widening is not a good way to overcome traffic problems but such modifications appear to be necessary in the minimum amount that would allow the design and implementation of a convenient and efficient public transport network. The result of this study proved the above hypothesis. This results reveal the importance of adherence to the results of urban detailed studies, including the development of urban road networks.