Variable Speed Limits on the M25 Motorway
In
September 1995 a variable speed limit pilot scheme was introduced to the
section of the M25 between Junctions 10 and 15. After a successful trial
it has now been implemented and there are plans to install the system on other
parts of the M25. Other councils around the U.K. are thinking about
setting up a similar system.
The system works by
reducing the speed limits when traffic is busy as a road can take more traffic
travelling at 50 than at 70 due to drivers being able to adopt shorter following
distances at a lower speed. Sensors
detect the speed and flow of traffic travelling on the motorway. When the onset
of congestion is predicted, the speed limit is automatically reduced to 60mph,
50mph or 40mph before critical flow is reached. This helps keep the
traffic moving and avoids the bursts of quickly moving traffic interrupted by
stationary, or very slowly moving, queues. The
limit is then raised when traffic flow improves. There are many
benefits for motorists:
Less
congestion and improved traffic flows
More
reliable, smoother journeys
Less
aggressive driving such as tailgating
Better
use of lanes and less lane changing
Reduction in accidents
Increased throughput of vehicles