The calibration and validation of HDM performance models in the Gauteng PMS

Abstract

Paper presented at the 21st Annual South African Transport Conference 15 - 18 July 2002 "Towards building capacity and accelerating delivery", CSIR International Convention Centre, Pretoria, South Africa.The Pavement Management System (PMS) of the Gauteng Provincial Government provides information required to maintain and manage the Road Network. One of the subsystems of the PMS is the optimisation system (dTIMS), which is used to model future pavement deterioration and to determine optimal maintenance and rehabilitation programs for given budget constraints. The estimated pavement performance is based on models developed by the World Bank and captured in the software HDM. In Gauteng these models were incorporated into the sub-system dTIMS. The models are universally applicable; but require regional calibration to be effective. To ensure local accuracy, 36 calibration sections have been set up in 1993 (Rohde et al, 1993) and have been carefully monitored annually by the province using a defined procedure (Van Zyl, 1994). The HDM prediction models were calibrated based on the observed deterioration of these 36 sections and the performance models are annually adjusted. The models as calibrated on these 36 sections are then used to model the entire network. This paper examines the validity of the models and calibration factors on the entire surfaced road network of Gautrans. The observed performance of the network over the last 10 years is compared to the predicted performance of the network, using the HDM models and calibration factors.