Daily traffic congestion on freeway networks around the world continues to increase, with detrimental effects on travel times, traffic safety, fuel consumption and environmental pollution. The annual cost of traffic congestion on European roads is estimated to approach 120 b€ or 1% of the GDP. Traffic congestion is only partly due to high demand, since the appearing congestion degrades the expensive infrastructure capacity essentially at the only times it is actually needed, i.e. during the daily peak periods. Traffic control measures, if properly designed and deployed, may lead to substantial savings of travel time, fuel consumption and environmental impact, along with an improvement of traffic safety. The presentation will outline the related traffic control problems and methods, with a focus on optimal control and feedback approaches. More specifically, the areas of macroscopic traffic flow modeling, local and coordinated ramp metering, variable speed limit control, mainstream traffic flow control, merging traffic control and route information and guidance will be addressed, along with the presentation of some selected field results. Current and future prospects, emerging developments and needs in relation to VACS (vehicle automation and communication systems) and their implications for freeway traffic and control will also be addressed.