Application of PBRRS RAPSA for Eastern Cape metropolitan FMH roll-out

Abstract

A fundamental principle in safe road design is that a driver stays alert, warned and controlled to keep the vehicle on the road and in the appropriate lane. The safe systems approach aims to develop a “forgiving” roadway in which a driver is not severely punished for making a mistake through human error. This can be achieved by making allowance for clear zones and recovery areas when designing the road verge Placing of roadside furniture in a non-hazardous way is part of good roadside design. In cases where potential hazards cannot be placed outside the clear zone, road restraint systems need to be considered. Accepted principles and procedures are available in most geometric guidelines and have been expounded in the more recent draft TMH24 (2022) produced under the Road Traffic Management Corporation (RTMC). The document provides standards and requirements on road restraint systems as well as application of a risk-based approach for roadside design, referred to as Risk Assessment Procedure for South Africa (RAPSA, 2022). A case study was undertaken along the National Route 2, Section 11, in the Nelson Mandela Bay Metropole, where SANRAL are implementing their Freeway Management System (FMS). This involves the installation of monitoring and surveillance hardware mounted on reinforced concrete poles alongside the roadway. The aim of this study was to determine the necessity for (and economic viability of) installing performance-based road restraint systems (PBRRS) at these locations, utilising the RAPSA tool as an analytical tool. The results from the analysis indicated that restraint systems would be required to protect motorists from fatal injuries where potential hazards are located within 2m of the edge of surfacing. During this study, additional considerations emerged - key inputs, sensitivities, and areas that require careful judgment when considering this particular approach.