Performance assessment of signalised intersection using uav videography : a case study of the jorissen-bertha street intersection in Johannesburg

Papers presented virtually at the 41st International Southern African Transport Conference on 10-13 July 2023.Intersections are critical sections of a road network as they are designed to accommodate various conflicting movements. For signalised intersections with pre-timed controls in urban areas, it is essential to assess the performance of the signal timing plans at regular intervals. The objective of this study is to develop a method that could be employed to assess the performance of any signalised intersection using a typical intersection in Johannesburg as the case study. The method relies on video data gathering using Unmanned Aerial Vehicle, from which various traffic parameters such as the approach flow rate, saturation flow rate, headways and delays are measured. The performance of the intersection is assessed by comparing observed delays with theoretical delays computed using HCM delay models. The study showed that UAV video data can be processed relatively easily to measure various traffic flow parameters required to assess the performance of signalised intersections

Mechanistic response of conventional vs perpetual flexible pavements under similar loading condition : a 3-d finite element analysis

Papers presented virtually at the 41st International Southern African Transport Conference on 10-13 July 2023.A 3D finite element analysis was conducted on several models of conventional and perpetual pavements to assess the similarities and differences in their structural and fatigue response when both pavement types are subjected to varied axle load and wheel configurations. The models were designed as a five-layer pavement system made up of an asphalt surface laid on an asphalt binder course. The base used was a graded crushed stone of G1 quality. Asphalt materials were assumed to be viscoelastic, while the granular base, subbase and subgrade were assumed to be linearly elastic. All material properties conformed to the South African Mechanistic Design Method (SAMDM) Guideline. Tandem axle dual wheel loading produces the least safety factor and fatigue life, and the highest damage among other configurations. Perpetual pavement models from the same materials were found to be more structurally rigid when comparing strains and damage in the long term. They show more resistance to distress by traffic loading when compared to conventional pavements. It was concluded that a 3-Dimensional Finite Element Analysis (FEA) is a suitable tool for supporting Mechanistic-Empirical design methods and provides a platform for further investigation of the behaviour of perpetual pavements

Travel time reliability assessment of public transport : a case study of the Johannesburg bus rapid transit (brt) corridors

Papers presented virtually at the 41st International Southern African Transport Conference on 10-13 July 2043Travel time reliability is one of the key measures of transport network performance. It also provides an indication of the level of predictability of travel time from origin to destination for any mode of transport. This paper presents an investigation of the travel time reliability of the Bus Rapid Transit system in Johannesburg - the Rea Vaya Bus service. The study method involves field collection of travel time information through onboard surveys along the BRT corridors. Travel time reliability is measured using a set of indicators proposed by the Federal Highway Administration (FHWA) of the US Department of Transportation. Among the objectives of the study is to gain some insight into the critical operational and road network factors that impact travel time for both peak and off-peak periods. Some of the factors considered include commuter boarding and alighting delays, stop frequency and delays at intersections. From the study, one of the notable factors found to currently affect travel time reliability for the BRT system was additional delays from traffic signal disruption due to the ongoing load-shedding scheme implemented by the national power agency, ESKOM