A methodology is presented for estimating the area of influence of two similar non-recurrent congestion events in two of South Africa’s metros, Tshwane and Cape Town, by use of probe data. Congestion in South Africa’s big cities on most of the major highways is a very common phenomenon to any regular traveller and has a substantial economic impact due to lost time while in traffic. The proposed method utilizes historic TomTom probe data to determine the effect of a stationary truck on a major arterial during Monday morning peak hour traffic, in which some lanes are closed to traffic. The impact on the corridor and the immediate road network is presented both graphically as well as mathematically in terms of average travel time, average speed and delay. Historic probe data on the day of the incident is compared to 20 weeks’ data prior to the incident. The methodology is applicable to similar incidents in which no fatalities or serious injuries were sustained and standard incident clearance procedures were followed. A Custom Area Analysis and Custom Travel Time analysis were conducted to obtain historic data on the day of the incident and typical traffic days for comparison. The results demonstrated this methodology’s ability to represent the true state of traffic on a specified route during and after an incident, provided that there are enough probes on the route for the time sets investigated. Probe data provides reliable data that will benefit various entities to address their specific requirements, whether they be road authorities, emergency services, law enforcement, or the ordinary citizens.
Papers presented at the 36th Southern African Transport Conference, CSIR International Convention Centre, Pretoria, South Africa on 10-13 July 2017.