Delay measurement and prioritization of BRT at signalized intersection : the Johannesburg Reavaya as a case study

M.Ing. (Electrical Engineering)Abstract: Bus Rapid Transit (BRT) is a transit system that makes use of modern and state of the art buses to deliver quick, comfortable and relatively cheap services usually at metro-level capacity. This research focused on the BRT system used in Johannesburg called the “Reavaya” (which means ‘We are going’) which is also the BRT system that was used as a case study. It is a common practice in other developed and developing countries that when a BRT system is built, a prioritized signal control at intersections that gives a right-of-way to the BRT is included on its corridors. However, as noticed at traffic intersections, the Reavaya buses were not prioritized at intersections leading to delay and more travel time of bus. The project proposed a mathematical model that measured the control delay experienced by the bus at an un-prioritized signalized intersection. The model measured the extra delay caused by the bus deceleration on approaching the un-prioritized intersection and its subsequent acceleration back to its original travel speed. The result of the model proposed when used to measure delay was then compared with the results of the Canadian model and the on-site field measurement. The effect of complexity and geometry of intersections on delay was also studied using the models. A study on the effect of active prioritization of buses at signalized intersections was also conducted using SUMO (a simulation tool) and a comparison was drawn between traffic performance at un-prioritized intersections and traffic performance at prioritized intersections. From the result, it was found that the mathematical model proposed measured more accurately the overall delay experienced by a bus at a signalized intersection when compared to other delay models and the DT (delay time) component of the proposed model was very close to the on-site field measurement value (with as little as 1% difference at some intersections). It was also found that the use of active prioritization on the Reavaya corridors has great benefits. For the corridor simulated, there was about 68% reduction of waiting time at intersections, 13% reduction in CO2 emission, 15% reduction in NOx and PMx, 12% reduction in HC and 17% reduction in CO while having little impact on the travel time of the general traffic. For all of the edges considered, the maximum increase in the general traffic travel time, occupancy and waiting time at any intersection were 16%, 20%, 19% and 15% respectively and a maximum of 15% reduction in the speed the vehicle would need to cross over any of the intersection considered. Therefore active prioritization technique is a suitable priority technique that could be deployed