Driver Location Signs
When reporting an incident, tell the emergency services or Highways Agency what is written on the nearest sign to you, this will help them to find your exact location more quickly.
Remember it is illegal to use a hand-held mobile when driving, ask your passenger to report the incident or wait until you can safely stop in a lay-by or service area. The signs look like this:
More useful information: http://www.highways.gov.uk/heavygoodvehicle