Abstract
Wintertime darkness, weather, and road surface conditions affect road traffic significantly in the Nordic Countries. This paper is an introduction to a novel method of integrating variable speed limits with variable road lighting to minimise the socioeconomic costs of the traffic on a rural road section. The system maintains satisfactory level of road safety and quality of perceived traffic flow, while it minimises a cost function comprising of vehicle, time, environmental, accident and road lighting costs. The principles and key points in the development of the optimal control model are discussed. The ongoing implementation of the controlling system for a selected test site is described shortly.