Highways Agency

Your Questions Answered

Why are the works being carried out and what is the problem?

M25 Junction 25 was identified as a junction that would benefit from improvement and is included in the 92 junction priority action sites announced in October 2002. At Junction 25 the motorway was designed with only 2 lanes for through traffic, causing congestion through the junction during peak periods. The majority of the M25 carriageway in this area is dual 3-lane carriageway. The Holmesdale Tunnel was opened in 1984. The mechanical and electrical equipment installed at the time of construction is at the end of its life and is beyond economic repair.

Why are you doing the work?

The tunnel's mechanical and electrical equipment is reaching the end of its design life and needs to be replaced in line with current standards. M25 Junction 25 is being improved to reduce road traffic congestion and improve road safety.

How long will it take?

Construction will start 6 May 2006 and finish by December 2007.

What length of road is involved?

The tunnel is 650 metres long. There will be revised signing and gantries from about 1 mile west of Junction 25 to 1 mile east of the tunnel.

Who is paying for the work to be done?

The Highways Agency is funding the £75 million scheme.

Are the works co-ordinated with local authorities and other utilities?

We have had detailed discussions with the local authorities most directly affected by the proposals. They accept that the works are essential and have to take place.

When was work last done to this section of the M25?

The M25 Junction 25 westbound improvements were completed in 2002.

How long will the work take and is there anyway it could be carried out more quickly?

The work is scheduled to take 18 months and organised in a way that minimises the works period.

What are you doing to publicise this scheme to users of the M25?

There has been considerable advance notice. As part of our on-going campaign to keep the public informed we are conducting exhibitions, producing newsletters and regular updates. We will also be updating our website with information about the project and liasing with the media.

What are the key messages to users of the M25?

• Plan your journey before starting off
• Consider alternative routes
• Allow extra time for your journey
• Drive safely and obey temporary 40 mph speed limit signs

If you don't do the work now what would be the safety implications?

The tunnel safety equipment will become increasingly difficult to maintain. This will result in unplanned maintenance closures.

Why can't the work be carried out overnight and at weekends only?

The scale of the work is too great.

Will this section of the M25 Motorway still be open?

Yes. The Motorway will remain open with two lanes of traffic in each direction.

Why do the Junction 25 eastbound on slip and Junction 25 off slip need to be closed during the works?

Junction 25 is situated very close to the tunnel and it is not possible to have the M25 traffic in contraflow in the tunnel with these slip roads open.

Is it correct that during the work motorists won't be able to access the M25 Motorway at Junction 25?

Junction 25 Eastbound on-slip (clockwise) and Junction 25 Westbound off-slip (anti-clockwise) will be closed for the duration of the works. However, the Eastbound off-slip and Westbound on-slip will be open.

Will you be diverting traffic onto local roads?

No, through traffic should not leave the motorway. The signed diversion route from the closed slip roads will be to use the motorway via M25 Junction 24.

How much extra time should we allow for journeys?

On the motorway allow an additional 15 minutes at peak times through the works. For local adjacent roads allow approximately 20 - 30 minutes at peak times.

What if there is a major incident?

Emergency plans would be implemented in a similar way to the current operating arrangements. The tunnel will remain closed until it is safe to reopen.

What are the emergency plans for getting traffic away from the area?

The existing plans will be implemented.

How will contractor gain access to the site (tunnel) and is the tunnel roof to be used as a site office?

The location of the site offices will be at the corner of Great Cambridge Road and the A10 roundabout. Access to the tunnel roof and the use of local roads will be minimised. However, some works will require access to the tunnel roof and service buildings located on Holmesdale Road.

Why is tunnel ventilation needed?

Under normal conditions the tunnel will self ventilate through the action of passing vehicles. When traffic is slow moving the air quality can deteriorate and in these conditions mechanical ventilation is required.

In the event of an incident involving a tunnel fire, the ventilation system will be required to keep smoke and hot gasses away from tunnel users whilst the
tunnel is being evacuated.

Why can't the existing ventilation equipment just be replaced for Holmesdale Tunnel?

It is not possible to meet current design standards using the current equipment installed within the tunnel.

Will I hear the fan station from my house?

The ventilation fans will only be operated in times of congestion or emergency. The noise from the fans will be noticeable but not great.

Will tunnel ventilation change air quality?

There will be no change in ambient air quality levels as a result of the scheme. Air will be pushed through the tunnel in a similar way to the current ventilation system.

Commitments were made at the previous exhibition to improve the landscape/environment on the tunnel roof. What plans have the HA to complete this work?

Appropriate landscaping will be designed and implemented around the tunnel portals as part of the scheme.

How will the local environment be improved?

• New low noise surfacing
• Enhancing drainage schemes to maintain water quality of nearby watercourses
• Lighting and signalling designed to minimise visual impact
• Materials used in construction of fan station buildings to blend in with local townscape
• New planting of native vegetation to mitigate wildlife and visual impacts
• Retaining existing vegetation where appropriate

What about the future widening of the M25 to dual four lanes?

This project is compatible with the proposed M25 Widening and measures have been taken to prevent unnecessary and / or abortive works.

Why can't the work be delayed until the widening is carried out?

The benefits of the junction will be gained far earlier. The costs of maintaining the tunnel mechanical and electrical equipment will rapidly escalate over this period.