<P> By the early 2000s mobile phones were being used as the primary means of reporting accidents . This required the government to rethink marker posts . By early 2007, after experiments in the preceding four years on parts of the M25 and M6 showed a 10% improvement in emergency service response times, a programme to erect driver location signs at 500 - metre (547 yd) intervals on many motorways was commenced in England . The need for more visible roadside location information was shown in 2007, in an incident on a motorway before the driver location signs had been erected . The Devon and Somerset Fire & Rescue Service reported that after a serious collision on the M5, their control centre was inundated with mobile phone calls from drivers . Callers gave the operators locations stretching over 40 miles (64 km) of road . As a result, four emergency service centres were mobilised instead of just one . </P> <P> Research on trial sections of motorways showed that emergency service organisations responded 10 percent more rapidly when a motorway had driver location signs than when it did not . Driver locations signs are more visible than the small distance marker posts, enabling motorists to know their location more accurately and emergency services to reach incidents more quickly . The analysis of an exercise run by the Highways Agency (Exercise Hermes) in which a serious traffic accident was simulated reported that call handlers in control rooms should request marker post or location sign locations when taking calls from members of the public . </P> <P> Driver location signs have three pieces of information: </P> <Ul> <Li> The road identifier </Li> <Li> The carriageway identifier </Li> <Li> The location </Li> </Ul>

What are the small blue signs on motorways