Accident characteristics of Singapore's expressways

This paper presents the preliminary findings of an applied research project which seeks to examine accident trends and identify accident blackspots on two major expressways in Singapore. However, the main thrust of the research has concentrated upon investigating possible relationships between various forms of accident total/ rate and either traffic volume or traffic flow. Results from both linear and polynomial regression analysis are given within the paper. An integral part of the research has involved the derivation of expansion factors for converting short period counts to annual volumes which are required in the calculation of accident rates. Both this process and the daily variability of traffic volume found on both expressways are commented upon in the paper.