MODELING LEVEL CROSSINGS’ TRAVEL TIME AND DELAY CHARACTERISTICS OF ADDIS ABABA LIGHT RAIL TRANSIT (AA-LRT)

Abstract

Traffic modeling is simplified representation of a part of traffic reality that provides a better understanding and interpreting of the complex traffic interactions. The objectives of this study is modeling level crossings travel time and delay characteristics of Addis Ababa light rail transit (AA-LRT) using simulation and mathematical models and evaluate the operational characteristics of the level crossings. In the process of achieving the objectives, the study investigate about peak period vehicle volumes, compositions, routings, LRV arriving frequency ,speed and the delays experienced. To meet the objective of this research intersection geometry data from field and traffic flow data at selected intersections is done by video recording and manual counting. In addition travel time data using light rail transit and minibus taxi is collected by traveling using these modes to a statistical number of repetitions. Suitable data inputs in forms of traffic volume, vehicle composition, vehicle routing, speed, train headway, travel time and delay at different incidences including level crossings are prepared. These suitable data inputs are introduced into VISSIM and SPSS analysis soft wares. Finally, the results were interpreted and the key research findings were presented in two types; i.e. through VISSIM simulation and SPSS statistical models. At the CMC level crossing the baseline without LRT scenario the average delay of traffic is 134.62s/veh ,the actual scenario with 00:05:41 LRV headway the average delay of traffic is 135.2 s/veh the delay increased by 0.43% and twice arrival frequency scenario the delay is 136.22s/veh with an increase in delay of 0.76% from the actual conditions. At the Sebategna level crossing the baseline without LRT scenario the average delay of traffic is 22.31s/veh ,the actual scenario with 00:06:30 LRV headway the average delay of traffic is 23.53 s/veh the delay increased by 5.47% and twice arrival frequency scenario the delay is 33.11s/veh with an increase in delay of 40.7% from the actual conditions. Additionally as observed in the mathematical model equation, the train’s travel time is dependent on running time, delay at grade intersection, open door close door time, close door start movement time and stop open door time in descending order. It is concluded that the average additional delays at level crossings increase from the base scenario and with increasing light rail crossing frequencies. In addition, delay at the level crossing is the second important variable that contributes for the variability of train travel time at peak hours.