Mots clé effects; transport planning; traffic information system

Congestion is one of the biggest transport problems in urban areas. Road congestion occurs when traffic demand approaches or exceeds the available capacity of the road system. In congested conditions, vehicle speeds are reduced, thus increasing driving time. These conditions are also frustrating for drivers, and automobile accidents may be more frequent. Furthermore, vehicles burn unnecessary fuel when stuck and idling. Extreme traffic congestion is called a traffic jam.

Traffic congestion varies depending on the season of the year, the day of the week, and the time of the day. Also congestion is linked to weather condition, work zones, traffic incidents. The causes of traffic congestion can be recurring and non-recurring. Recurring congestion is caused by recurring demands that exist virtually every day, where road use exceeds existing capacity, while non-recurring congestion is caused by temporary disruptions, such as traffic accidents, road work zones, bad weather, special events taking place. Non-recurring congestion considerably reduces the available capacity and reliability of the entire transportation system.

Traffic congestion can be reduced by a decrease of single occupant vehicle use, and an increase in the use of public transit, bicycle and pedestrian facilities, by encouraging changes in commuters' travel habits, and, in general, by improving the efficiency of existing transportation services. A short-term solution to mitigate congestion is a more effective traffic management system. Measures to be taken in case of congestion caused by traffic accidents are reduction of time needed to detect and respond to accidents and to clear the site of the accident, as well as timely information of road users via radio, suggesting the use of alternative roads. Similarly, in the case of road work zones, the concerned public must be made aware in time via radio and mail suggesting alternative roads and encouraging the use of public transport. Often, people discover the benefits of public transport and continue using public transport even after roadworks are completed and the private car could again be used.

Another solution to prevent congestion is more efficient traffic scheduling to optimize road use, i.e. commercial traffic at night, staggering working hours and decentralizing administrative operations for large companies. Long and short distance commuting to work with private cars could be reduced by providing integrated, accessible and efficient urban public transportation. Single-passenger commuting to work should be discouraged.