M25 J25 Improvement

Scheme outline

An upgrade of the existing roundabout and sliproads at the junction between the M25 and A10. The scheme is intended to improve the performance of the junction and improve reliability for all traffic, specifically reducing the regular queues on the sliproads that tail back on to the mainline of the motorway. It also aims to reduce the number of collisions at the junction, improve pedestrian and cycle facilities and increase overall capacity.

At present, three options are proposed, all of which will involve improving the existing layout.

Option 1 would widen the roundabout to three or four lanes throughout, widen the approach from the northbound A10, and provide improved pedestrian/cycle facilities to replace those lost by the widening.

Option 2 is the same as option 1, but with additional widening on the sliproads from the roundabout to the M25 in both directions and a dedicated lane from the clockwise M25 to the northbound A10, bypassing the roundabout.

Option 3 is the same as option 2, with a dedicated bypass lane from the northbound A10 to the anti-clockwise M25 and widening of the southbound A10 to provided a dedicated left turn lane from the junction to the A1055 Bullsmoor Lane.

2020 - 2022
In preparation
Junction improvement
with parts under motorway restrictions
Highway authority


28 July 2017

Option 2 has been selected as the preferred route after the public consultation.

More information


With thanks to Barry Salter for information on this page.