A4 Crossings Update - message from Transport for London

This was received by us yesterday (23^rd July) from Laura Dyett of Transport for London, Please let me know what you think.

A4 Great West Road – s106 proposals and issues at junction with Clayponds Avenue

I would like to start by addressing some general points raised regarding junction layouts and signal timings:

·         Louvers –

Ø  The louvers over the green traffic signals at the A4/Clayponds Avenue and other nearby junctions cannot be removed as they are an essential safety feature.

Ø  Their purpose is to prevent vehicles on the A4 that are held on a red signal at the first stop line from seeing through to the green signal at the second stop line associated with the pedestrian crossing. If the green signal was left uncovered then there is the possibility that these vehicles will mistakenly proceed into the junction and collide with vehicles entering from the side roads.

Ø  Louvers are never placed over a red signal so they have no effect on the visibility of the red signal for vehicles turning from the side roads onto the A4.

·         Signal timings

Ø  Request for longer ‘green man’ time – The steady green man is an invitation to cross and is designed to ensure that anyone who is waiting starts their crossing movement. It is followed by a safety critical clearance period, the duration of which is determined by the crossing distance.  This ensures that anyone starting to cross when the green man goes off will complete the crossing movement before vehicles receive a green signal. We have checked and can verify that all pedestrian timings adhere to Department for Transport standards.

Ø  One suggestion is to hold all vehicles on a red signal whilst pedestrians cross the A4. This measure would result in a significant increase in congestion on both the A4 and adjoining side roads as there would be a much longer period of time when vehicles were not moving through the junction. Any increase in congestion would not only have an impact on the economy but also on noise and air pollution levels, which are already high alongside the A4.

·         Drivers’ eye level signals – These are not currently allowed within our national traffic sign regulations. We would need a change to the regulations before we could trial anything on our road network.

 In regards of the measures that we propose to implement and their timings:

·         At the A4/Clayponds Avenue:

Ø  Louvers – In March we altered the angle of two of the louvers over the signals at the pedestrian crossings so that the slats were vertical rather than the standard horizontal.

This was done to improve the visibility of the green/amber signal for those turning left from Clayponds Avenue onto the A4, which from the north arm is the predominant turning movement onto the A4. This has helped to improve the visibility for left turners but an issue remains with those turning right from Clayponds Avenue or u-turning on the A4. As a result we have removed the louvers on the amber signals at the crossing on the eastbound carriageway to further increase visibility of the signals. This is being done on a trial basis as we need to monitor the junction to ensure this doesn’t introduce additional problems.

Ø  Signal timings – Our engineers have adjusted the point when the crossings change in the signal cycle to ensure that there is no traffic approaching when it changes.

Ø  Installing advanced warning signs of traffic signals ahead – to be installed on both Clayponds Avenue approaches to the junction by the end of this month.

Ø  Lighting under the M4 – we are leaving the light on 24 hours under the M4 structure above the crossing on the east arm of the junction to see if this improves visibility of the crossing.

Ø  Pedestrian crossing stop line – we are proposing to increase the width of the vehicle stop line in front of the crossing and increase the distance between the stop line and the crossing; both to the maximum measurement permissible by the Department for Transport. This should help to make the stop line more visible and provide additional stopping distance for those who mistakenly run through the red light. We will do this as soon as possible after the Olympics.

Ø  Signal heads – we will replace all of the signal heads at the pedestrian crossings so that they are cleaner and therefore more visible to drivers. This should be done by the end of August.

These measures are in addition to those we agreed as the Isleworth and Brentford Area Committee (IBAC) meeting in December 2010. In regards of these measures:

Ø  These include providing a signal controlled pedestrian crossing on the north arm of the junction, moving some pedestrian push buttons further away from the kerb edge, replacing all other signal heads, providing an additional signal head at the pedestrian crossings and relocating an existing signal head at these locations. The last three of these measures will help to improve visibility of the existing pedestrian crossings.

These measures are currently being designed by our Traffic Engineers who have to go through a number of stages in order to come up with a workable and approved design; particularly because we are required to alter the layout of the junction and signal timings in order to incorporate a crossing on the north arm. The situation is complicated by the fact that the existing signal equipment at the junction needs fully replacing before we can make any significant changes to it because it is too old to support additional requirements. We expect preliminary design work to conclude by the end of this year after which we will proceed with detailed design work and securing permits to carry out the work on the road. We anticipate that we will be able to implement the measures towards the end of next year.

Ø  At the A4/Windmill Road:

Ø  Installing advanced warning signs of traffic signals ahead – as at A4/Clayponds Avenue

Ø  Pedestrian crossing stop line – as at A4/Clayponds Avenue

Ø  IBAC measures – Providing a signal controlled pedestrian crossing on the south arm of the junction, moving some pedestrian push buttons further away from the kerb edge, providing an additional signal head at the pedestrian crossings, relocating an existing signal head at these locations and replacing all signal heads. Same progress status as at A4/Clayponds Avenue.

·         At the A4/Lionel Road:

Ø  Installing advanced warning signs of traffic signals ahead – on Lionel Road (south arm) approach only.

Ø  IBAC measures - moving some pedestrian push buttons further away from the kerb edge, providing an additional signal head at the pedestrian crossings, relocating an existing signal head at these locations and replacing all signal heads. These measures should be implemented early next year.

·         At the A4/Ealing Road:

Ø  IBAC measures - moving some pedestrian push buttons further away from the kerb edge, providing an additional signal head at the pedestrian crossing, relocating an existing signal head at this location and replacing all signal heads. These measures should be implemented early next year.

·         Standalone crossing near to A4/Brook Lane

·         IBAC measures - moving some pedestrian push buttons further away from the kerb edge and replacing all signal heads. These measures should be implemented early next year.

In regards of progress on these measures prior to the Olympics, from the 1^st of July until after the Paralympic Games there is an embargo on carrying out all but essential maintenance works on the Transport for London Road Network. A large majority of our staff will be at least partially re-deployed to Olympics based roles during the Games and it will take some time to revert our road network back to its previous state afterwards. All of this means that there will be an extended period of time where we cannot introduce any further measures at these junctions.

Finally, the measures we plan to implement will only help to reduce the occurrences of ‘red light running’ caused by vehicles who fail to see the traffic signal. From our own site observations, made during the school run period, we believe that some drivers intentionally run through the red light to avoid waiting for the pedestrian crossing phase to run. This is clearly an issue that needs to be addressed by enforcement activity and as such we have spoken to the Police about this.