Abstract
Mobility has been increasing significantly in the last few decades and will continue to increase. On road stretches which have insufficient capacity, traffic becomes congested. Traffic congestion has a negative impact on the economy and on the quality of people’s lives. Road users experience delay and stress, and environmental pollution increases. The effects of traffic congestion on traffic safety, however, are less obvious. This literature review investigates the relationship between congestion and safety at road sections of the main road network (mainly motorways) and specifically looks at unstable and congested traffic conditions.