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Road M25 West widening

Widening of the M25 between the M4 (J15) and the M3 (J12) (Heathrow section) to give it 6 lanes in each direction.

The M25 western section near Heathrow airport is one of the busiest roads in Europe, catering for over 200,000 vehicles per day. (The AA states that the figure is 250,000 vehicles per day, which is twice the design capacity of this section). Widening is intended to relieve some of the endemic congestion.

Phasing the work

The first stage of the project, now complete, was to provide five lanes between J14 (Heathrow Terminal 4) and J12, with work being carried out between 05 Jan 2004 and 29 Jul 2004.

The second phase was the equivalent northbound work (also five lanes), which will took place from 30 July 2004 to the end of that year.

The third phase was to provide six lanes southbound between J15 (M4) and J14 during the first half of 2005; during the second half of 2005, the northbound carriageway was also be widened to six lanes.

The work was completed ahead of schedule on 28 November 2005

The roadworks

There were still four lanes available through the roadworks but they were narrower, and HGVs were only be able to use lanes 1 and 2. A 40mph (60kph) speed limit was in force.

Terminal 5 Spur Road

As part of these works, the new spur road for Terminal 5 was also constructed (although it will only open when the terminal opens). It is free-flow, i.e. enabling vehicles to travel between both directions of the M25 and the new terminal without stopping at lights or roundabouts.

Part of the reason for the widening of this section is to cater for increased demand expected from Terminal 5.

Mixed reaction

The widening work has met with appreciation from road groups such as the AA and RAC (who believe that widening of this extremely congested section is long overdue) but dismay from environmental or sustainability groups such as Friends of the Earth and Transport 2000. The decision to go ahead with widening is only a recent one; before coming to power in 1995, John Prescott claimed the plan to be "lunacy".

The London Orbit multi-modal study (MMS) which studied orbital travel around London in extensive detail came to the conclusion that M25 widening would only be beneficial if road-user charging were introduced in connection with it. At present, road-user charging is not being taken forward; the Highways Agency is, however, considering ramp-metering on a number of M25 junctions.

Ramp metering involves stop lights at entry slip-roads which are controlled by computer measurement of the flow of traffic already on the motorway; they are designed to keep traffic moving by "trickling" new traffic into the existing stream so that the flowing traffic is not extensively disrupted.


(newest first)
Car sharing lanes considered for western M25
2005-03-30 19:52:03

Following on from plans to dedicate the new M1 lanes between Luton and St Albans to cars with multiple occupants, the transport secretary has asked the Highways Agency to investigate dedicating to car-sharers the new M25 lanes currently under construction on the western part of the motorway near Heathrow.

Phase two of M25 widening starts
2004-07-27 14:04:02

Thursday (29 July) marks the changeover between widening of the southbound section of the M25 between J12 and J14, to widening of the northbound section.

M25 cameras snap 10,000
2004-04-13 18:19:15

Over the last 8 weeks, speed cameras enforcing the temporary 40mph speed limit in the roadworks section of the M25 around Heathrow have caught over 10,000 motorists. Motoring organisations are angry that the limit was not suspended over the Easter weekend when cones were removed and work suspended temporarily.

Links & Sources

  1. Information video (30MB) to played at service stations and ports
  2. Highways Agency: M25 Jct 12 to 15 widening

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