A4 Safer Roads - Speed Limit Reduction

Closes 7 Oct 2022

Opened 26 Aug 2022


We consult residents, commuters, businesses and stakeholders to understand what people think about proposed developments, changes to our roads and pavements, or other traffic-related issues.


The government announced, on 28 November 2016, a £3 billion roads investment package, £100 million of which was targeted at reducing the number and severity of fatal and serious injury collisions on 50 of England’s local 'A' road sections - the Safer Roads Fund. Of those 50 road sections, identified by analysis by the Road Safety Foundation, 37 were assessed as being 'high-risk', including the A4 in Slough between junctions 7 and 5 of the M4.

We submitted a bid to the Safer Roads Fund and were granted £1.7 million by the Department for Transport for a number of measures to reduce the risk of fatal and serious injury collisions occurring along the A4 in Slough. These include a proposed change in speed limits throughout the relevant section.

The A4 in Slough is a mixture of single- and dual-carriageway road, with many uncontrolled junctions and entrances which increase the risk of side impacts with turning traffic. There isn’t enough space to revise the road layout, and reducing the speed limit would reduce the risk of serious injuries occurring in these types of collisions.

What are we proposing?

The map below shows our proposed changes to speed limits.

We propose introducing a consistent 30mph speed limit along the A4 (Bath Road, High Street, Wellington Street, Sussex Place, London Road and Colnbrook By-Pass) from the western borough boundary to a point on the Colnbrook By-Pass near Sutton Lane. This would mean reducing the speed limit from the existing 40mph west of Twinches Lane and east of Fox Road.

As well as a lower speed limit throughout, consistency of speed limit is also important.

We expect the proposed reduction in speed limit and consistency of speed limit would lead to the following benefits:

  • fewer injuries to vulnerable road users, especially pedestrians
  • fewer injuries to vehicle occupants
  • fewer road incidents involving turning and speeding traffic
  • reduced severity of any collisions
  • safer, more predictable patterns of driver behaviour
  • better overall decision making by drivers
  • a safer environment for children
  • improved air quality
  • reduced CO2  emissions
  • reduced congestion at signalised junctions
  • more consistent traffic flow
  • more reliable journey times
  • reduced traffic
  • increased cycling and walking, maintaining and improving physical and mental health

We also propose a reduction in the speed limit along the A4 Colnbrook By-Pass between Sutton Lane and Lakeside Road from 60mph to 40mph, to ensure a transition to / from the existing 50mph limit between Lakeside Road and the eastern borough boundary at the M25 bridge.

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What about enforcement and monitoring?

Enforcement of speed limits would continue to be essential in order to maximise the benefits. We are therefore consulting Thames Valley Police at every stage in this process.

We would also monitor the speed of traffic before and after introduction of the reduced speed limits to see how effective they are.

What about the Traffic Regulation Order?

For the notice relating to the proposed Traffic Regulation Order required to make this change (A4 Slough (30mph and 40mph Speed Limit) Order 2022) please see here.


The proposed speed limit reductions would support our work to improve cycling and walking facilities along the A4. We are also investigating additional road safety measures as part of our A4 Safer Roads scheme, which addresses the risk of fatal and serious injury collisions on the A4.

Why your views matter

We want to know your views on our proposed speed limit reductions and any impacts they may have, including any objections or representations relating to the proposed Traffic Regulation Order required to make this change (A4 Slough (30mph and 40mph Speed Limit) Order 2022).

All objections must specify the grounds on which they are made.

Further information

If you would like further information to enable you to respond, or a copy of this information in another format or language, please:

  • email us at TransportPlanning@slough.gov.uk, or
  • write to us at A4 Safer Roads - Speed Limit Reduction - Enquiry, Transport, Slough Borough Council, Observatory House, 25 Windsor Road, Slough SL1 2EL, or
  • call us on 01753 475111 (asking for a message about "A4 Safer Roads - Speed Limit Reduction - Enquiry" to be passed to the Transport team)

How to respond

Please, if possible, respond using the Online Survey form below:

If you are unable to use the online survey, please instead respond:

  • by email to TransportPlanning@slough.gov.uk, or
  • in writing to A4 Safer Roads - Speed Limit Reduction - Response, Transport, Slough Borough Council, Observatory House, 25 Windsor Road, Slough SL1 2EL

Please respond by 23:59 on Friday 7 October 2022.

We want to hear from you!


  • Anyone from any background


  • Local Transport Plan