Article by Prof Johann Andersen
Traffic congestion in cities around the world is becoming progressively more concerning as travel demand exceeds roadway capacity, impacting mobility, productivity and the environment. If you recall, prior to the COVID-19 pandemic, that was also evident in Stellenbosch! On any given day, it was a nightmare to traverse across town along the R44. In many cases, infrastructure upgrades that physically increase capacity are not viable solutions to solve congestion. “More and more, traffic engineers are employing technology to amplify the capacity of road networks,” says Prof Johann Andersen, Head: Intelligent Transportation Systems & Stellenbosch Smart Mobility Lab, in the Department of Civil Engineering, Stellenbosch University.
The application of Traffic-Adaptive-Signal-Control (TASC) is an application of technology to assist in addressing everyday congestion. TASC refers to the real-time control of signalised intersections, based on the provision of current detector data. This enables the real-time adjustment of signalisation parameters in order to increase vehicle throughput and reduce congestion, rather than relying on often outdated pre-set configurations that do not take current traffic conditions into account. Not only does a TASC system rely on real-time traffic data input, but also on a representative traffic model that simulates several signalisation options to generate a suitable allocation of green-time shares within the network. TASC can optimise the flow of traffic at an individual intersection while simultaneously coordinating the traffic flow on a network level.
The Stellenbosch TASC project started as a research project at the Stellenbosch Smart Mobility Lab (SSML) at Stellenbosch University. Master’s student at the time, Wilko Mohr, was investigating the feasibility of using Traffic-Adaptive Signal Control (TASC) in a developing country context to optimise and manage the flow of vehicles along a signalised arterial. His study leader was Megan Bruwer. The project is executed in partnership with the Stellenbosch Municipality and industry partners the PTV Group, Syntell and Techso. The aim was to use Stellenbosch as a testbed environment to implement a TASC solution to gauge the applicability of using this approach in a more developing world context. Due to the model-based nature of the TASC system, scenario testing provides coordinated network signal plans every 5 minutes and optimised local signal plans every second. “Initially, only the R44 corridor in Stellenbosch was simulated with TASC control with average delay reduction of up to 32% and an average increase in vehicle speed of up to 49% in specific peak periods,” notes Megan Bruwer, Lecturer: Department of Civil Engineering and Project Coordinator: Stellenbosch Smart Mobility Lab.
“Following the successful modelling and simulation of the system, showing significant potential in reducing the impact of congestion, real-world implementation is currently underway,” adds Deon Louw, Director of Infrastructure Services at Stellenbosch Municipality. The first intersection forming part of the initial testbed along the R44 corridor (Van Rheede Street), went live on 15 July 2020. More intersections will be systematically added along the R44. The Stellenbosch Municipality aims to roll out this system across the network.
The project represents the first real-world test of TASC in Africa. This project is a testimony to a collaborative effort between the public sector, academia and the private sector.
Left: On-site team, remotely supported by PTV experts via MS Teams, are from the left Patrick Beyer (Syntell), Johan Fullard (Stellenbosch Municipality), Anton Struwig (Techso) and Megan Bruwer (SSML, Stellenbosch University).
Centre: The intersection at the R44 and Van Rheede Street in Stellenbosch.
Right: Switching over to PTV control.