Impact of changes in road speed limits on arterial roads

In 2009, the Traffic Police Department (TP) and Land Transport Authority (LTA) of Singapore commissioned a research study on the impact of changes in road speed limits on road safety and traffic efficiency following a comprehensive speed limit review on arterial roads in Year 2005/2006. The intent of the study was to allow TP/LTA to have a better understanding of the key issues that need to be considered in future speed limit revisions to minimise any negative consequences and achieve strategic objectives (e.g. enhancing road safety and traffic efficiency). From the crash occurrences and speed profiles, the results show that the safety level and general operating speed remains relatively unchanged despite the raised speed limit. It is inferred that there is a better match between motoristsr choice of operating speed and the regulatory speed limit following the changes in speed limit. The study suggests that speed limit increases can be considered in situations where existing geometry and operating conditions permit, with no major land-use developments in the near future. On the other hand, reduction in speed limits should be considered when there is an increase in crash occurrences; changes in the operating environment; and an increase in proportion of non-motorised road users e.g. pedestrians.