Australia's first full scale variable speed limit system has recently been implemented on the Western Ring Road in Melbourne. The system extends over 24 kilometres and controls 68 changeable regulatory speed limit signs, which are distributed along both carriageways of the freeway. The system controlling the changeable signs is driven by a complex series of algorithms that can be logically divided into three main parts. These cover the processing of input data, the calculation of recommended speed limits, and the checking of the feasibility and logic of recommended changes. Within this framework there are a number of safety specific components that provide automated control through defined rules and constraints, and specific failure and recovery systems. These are supported by functions that allow manual intervention by operators. This paper provides a general overview of the variable speed limit system that has been deployed, and a more specific review on the program controlling the speed limit signs and the primary safety components embedded in the system. (Author/publisher) For the covering entry of this conference, please see ITRD abstract no. E208431.
Abstract