Setting of optimum signal timing using vissim software to improve the existing traffic operating condition of t and four leg intersection of chittagong city

Now a day’s traffic congestion issues in Chittagong city is becoming worse day by day. This happens due to the slow-moving vehicles, occupied footpath, unauthorized car and bus/truck lay over, traditional traffic signal timings Government authorities are building flyovers to abate the intensity of congestion which is not always a great solution but cost a huge amount of money. Saturation flow in any intersection is huge to control with traditional traffic signal system. The aim of this paper is to assess and develop the traffic operations at the AK Khan (T) and Alongkar (four leg) intersection which are situate near the most congested portion of Chittagong city due to bus terminal area. Traffic count studies are conducted to determine the number, movement and classification of vehicles at an intersection. In this study, an improved traffic signal timings i.e. green time, amber time and red time have selected for continuous movement of vehicles through the intersection to ameliorate the situation of delays, average speed and queue length to do that videography survey has conducted at 15 minutes of intervals during estimated peak hour. In addition, geometric, traffic and signalized data were collected during peak time periods. In this study, we calculated the signal timings (Green time, Yellow time, Red time, Cycle time and Lost time) and it is optimized by VISSIM which is a traffic simulation software. Delay time and average speed are determined manually and compared after optimization in VISSIM. Another alternative solution is given i.e. construction of one through overpass for one direction (from AK Khan to Alongkar) for through vehicles to have more improved traffic condition. These solutions will be advantageous for the signalized intersections especially during rush hours, decreasing the travel cost, greenhouse gas emission & number of accidents, increasing the efficiency of the road network, improving traffic flow and traffic operations.