Derivation (traffic)
A derivation is carried out of the traffic when a full closure of a road tunnel or a carriageway is arranged, and no alternative traffic management on the same traffic route is possible. The reason for such a full closure can be, for example, an accident with dangerous goods or a pile- up. The execution of a traffic diversion is carried out (often on behalf of the traffic authority ) by the police.
features
With the help of barrier devices ( barrier beacons and barrier boards ), traffic is gradually brought together onto a lane and then directed onto the deceleration lane , in order to then be diverted to the subordinate road network. Advance warning devices or police officers can be used in advance to make road users aware of the diversion . In contrast to diversions, traffic is not returned to the traffic route via a diversion route behind the blocked off section.
In the event that there are still vehicles between the blocking point and the junction at which the traffic is diverted, the police can instruct the vehicle drivers to turn their vehicles around. It then leads these vehicles back to the last free junction against the prescribed direction of travel. In order to ensure the smoothest possible diversion, the returned vehicles are either led via the actual driveway of the last free junction onto the downstream road network, or via the regular exit. The decision on this is made by the police depending on the design and performance of the junction, in particular the junction at the interface with the downstream road network.
Traffic diversion has the advantage that, in the event of long-term closures, rescue workers can reach the scene more easily and road users do not have to wait unnecessarily long for the journey to continue.