Slow or Stationary Vehicle Warning

Slow or stationary vehicle warning is a
safety-related Cooperative Intelligent Transport
System (C-ITS) service that mainly aims to reduce
the number of accidents in connection to slow or stationary vehicles, e.g. emergency vehicles and
road maintenance vehicles. Slow or stationary
vehicle warning contributes to the elimination
of traffic jams.


Accidents often occur during bad weather and
visibility conditions, whereby the visibility of slow or
stationary vehicles on the hard shoulder or driving lanes is limited. A high risk of accidents occurs, especially on driving lanes, if the driving speed is excessively high in relation to the slow or stationary vehicle.


For the implementation of this service in Hessen, the road maintenance and emergency vehicles will be equipped with the necessary technology (ETSI G5) for a vehicle-to-vehicle (V2V) communication to send appropriate messages and alert the drivers in advance. In Niedersachsen (Lower Saxony), in contrast, the SSVW messages are triggered centralised or decentralised by traffic management centres (TMC).



  • Reduction of the number and severity of accidents on motorways (for both the employees of road maintenance and emergency vehicles and drivers)
  • Zero fatalities on motorways caused by road maintenance and emergency vehicles


  • Minimal impact of road capacity reduction caused by road maintenance or emergency vehicles
  • Provision of reliable current traffic information for travellers

Environmental issues

  • Reduction of pollutant emissions

Implemented in