M6 Thelwall Viaduct bridge joint replacement scheme
We’re replacing the bridge joints on the iconic Thelwall Viaduct, in Warrington, which carries the M6 motorway over the Manchester Ship Canal and the River Mersey.
Latest updates
-
15 October 2026
24/7 contraflow at M6 Thelwall Viaduct
A contraflow will run until winter 2027-28, with traffic running at 40mph.
Our scheme involves two contraflow phases, first northbound and then southbound.
This allows us to maintain the same lane capacity, so we can work safely while keeping traffic moving.
The northbound contraflow starts on 19 October, allowing us to work on the northbound carriageway.
When it's in place, the northbound contraflow will use this traffic management 24/7 between junctions 20 and 21 for the next few months:
Daytime
- four lanes of traffic maintained in both directions
- a 40mph speed restriction on both carriageways.
- one lane of northbound traffic running on the southbound carriageway
Night-time
- 4 lanes of traffic on the southbound carriageway
- one lane of northbound traffic running on the southbound carriageway
- northbound carriageway restricted to one lane between 10pm and 5am
- junction 21 northbound exit slip remains open at all times during the first phase of traffic management
Closures
Tuesday 20 October - M6 northbound junctions 20 and 21
Closed overnight (10pm-5am).
As part of our works at Thelwall Viaduct, a full overnight closure of the northbound carriageway is required.
Diversions
During full overnight closures, motorists can follow the route via the M56, M60 and M62 in both directions. Clear diversion signs will be in place.
M6 Thelwall Viaduct northern carriageway diversion route map.
M6 Thelwall Viaduct southern carriageway diversion route map.
Project information
Overview
Replacing these joints is essential to:
- reduce the risk of unexpected closures
- keep the bridge working safely and effectively
- minimise disruption for road users over the long term
Milestones
We’ve carefully planned our work at M6 Thelwall Viaduct, which will be carried out in stages:
Stage 1 – September 2026
Northbound contraflow set-up on the M6 motorway, along with scaffolding installation beneath the viaduct.
Stage 2 – Mid October 2026 to March 2027
Bridge joint replacement works on the northbound side of the M6 viaduct.
Stage 3 – Spring 2027
Introduction of the southbound contraflow on the M6 motorway.
Stage 4 – Spring to December 2027
Bridge joint replacement works on the southbound side of the viaduct and removing the contraflow layout.
Stage 5 – Winter 2027-28
Resurfacing, road marking and road studs on both carriageways under overnight lane closures, with traffic sensors replaced under overnight full closures on both carriageways.
Please note, additional traffic management phases may be needed during the scheme.
We’ll update this web page in due course. We always aim to work to the programme, however unforeseen circumstances or adverse weather conditions may mean changes.
Benefits
Replacing these bridge joints is essential to reduce the risk of unexpected closures, keep the bridge working safely and effectively, and minimise disruption for road users over the long term.
Traffic management and diversions
We'll need to close the M6 from time to time during our work.
During full overnight closures, you'll be diverted by the M56, M60 and M62 in both directions. We'll clearly sign diversion routes.
M6 Thelwall Viaduct northern carriageway diversion route map.
M6 Thelwall Viaduct southern carriageway diversion route map.
Documents
Traffic information
Information about scheduled roadworks and events on our motorways and major roads.Sign up for updates!
Keep up to date with what's happening on this scheme by signing up to our updates.
