Mehdi Fallah Tafti - PhD in Traffic Engineering, MIET, CEng (UK) Assistant Professor, School of Engineering, Yazd University, Iran

In the light of increasing demand for further application of Variable Speed Limit Control Systems, it is essential to ensure that these systems are robust enough to produce the impacts required to meet the specific objectives set for their implementation. The extent of success of Variable Speed Control Systems largely depends on the underlying approaches and methods used in their algorithms logic. In this article, first a critical review of different approaches and methods for Variable Speed Control with emphasis on those currently implemented in real world is made. Then based on an assessment of the performance of existing systems especially the UK system (known as Controlled Motorways), a number of suggestions for further modifications to the existing rule-based practical systems is made. Considering the limitations inherited in the currently used practical systems, merits for the development and application of new network-oriented variable speed control systems based on robust theoretical control models and/or artificial intelligence techniques are highlighted.

Variable Speed Control, Controlled Motorways, Congestion Management, Traffic Management, Intelligent Transport Systems