Analysis of distance headway and density at a variable message signs network in Kuala Lumpur

Variable message signs (VMS), also known as changeable message signs (CMS) or dynamic message signs (DMS), are traffic control devices to communicate with motorists. A VMS is generally used to inform motorists the roadway, traffic, or weather conditions. It is also used to display travel times and public service announcements. This study attempts to utilize archived traffic data from the MRR1 freeway area in Kuala Lumpur to assess the effects of VMS in terms of distance headway and density. Results show that usage of Variable Message Signs reduces the density during the duration of the incident until the clearing of the resulting congestion by a significant amount. The results demonstrate that VMS has no significant impact on distance headway.