Implementation of Malaysian National Axle Load Policies through Weight Restriction Orders 1989, 2003 & 2017

Abstract

Axle Load Study in 1987 had led to the formulation of Weight Restriction Order (WRO) 1989 for truck legal axle weights based on Short Term Axle Load (STAL) policy, which considers HA loads with no checking done on HB load. Medium Term Axle Load (MTAL) policy was later implemented in 2003 by the introduction of WRO 2003. MTAL are loadings derived from HA load or 45 units HB loading guided along the centreline. A new assessment load model to evaluate existing bridge carrying capacity is proposed in the new axle load study conducted in 2016. The findings were accordingly gazetted in 2017 with the issuance of WRO 2017. Oblivious of these studies, many Malaysian engineers today are not informed of the rationales or basis of the practices, especially those related to bridge assessment. The purpose of this paper is to revisit these studies and discuss pertinent decisions made with regard to the national axle load policies. Based on the comparison between the previous and new assessment procedure, bridges that were rated as capable of safely carrying the load equivalent to MTAL are capable of safely carrying the vehicles that are in compliance with WRO 2017.