Sizewell C related Traffic Management, Road Closures & Rail Movements

See below for current and up and coming road closures and traffic management in relation to the Sizewell C project:

Engineering Train Movements

As part of the track renewals and the installation of the Green Rail Route there an engineering train known as the Tamper Train running along the line from Saxmundham Road level crossing into the TCA carrying out tamping work of the track ballast over the next few weeks.

A12 Closures

Friday Street

The A12 / A1094 will be closed from 8pm to 5am on the nights of 13 to 17 July for resurfacing works. The diversion routes will be:

A12 Diversion Route: A1152, B1069, A1094, B1069, B1122 and vice versa

A1094 Diversion Route (South): A1094, B1069, A1152, A12

A1094 Diversion Route (North): A1094, B1069, B1122, A12

Stratford St Andrew

The A12 south of Stratford St Andrew will be closed at nights (8pm to 6am) from Friday 3 to Tuesday 7 July 2026, ending 6am on Tuesday 7 July, for a water mains diversion. The diversion route is A12, A1094, B1069, A1152, A12.

Marlesford

The A12 at Marlesford will be closed at nights (8pm-5am) from 27 to 31 July to enable road improvements. The diversion route is A1152, B1069, A1094 and vice versa.

A further closure of the A12 at Marlesford is likely in Q3/Q4 2026 subject to relevant permissions to being granted.

Darsham

The A12 at Darsham will be closed at nights (9pm to 5am) for two nights, 20 to 21 July ending at 5am 22 July, for surfacing.

The A12 at Darsham will be closed at the following times for works associated with a new pedestrian crossing:

• Weeknights (9pm-6am) from 10 to 21 August.

The northbound diversion route is A1120, B1116, B1117, A144. The southbound diversion route is B1387, B1125, B1122.

• Weeknights (8pm to 5am) from 7 to 18 September, 5 to 16 October. Following this, the A12 at Darsham will be closed for a full weekend, 8pm Friday 30 October to 5am Monday 1 November.

The diversion route is A12, A14, A140, A143, A146, A12 and vice versa.

B1122 Closures

Leiston

From 20 July to 30 August, Abbey Road (B1122) will be closed 24/7 at the Leiston level crossing. The eastern end of Westward Ho will also be closed for approximately 80 metres from the junction with Abbey Road.  Pedestrian access will be maintained.

Yoxford to Theberton

There is a closure of the B1122 (Middleton Road) for one night, 7-8 July (11:30pm to 5:30am) operated by Network Rail. This closure is not associated with Sizewell C.

There are likely to be several weeks of weeknight closures of the B1122 following the summer holiday period. We will continue to provide updates on the works tracker including more specific details when they are available.

Other Road Closures

Darsham

Willow Marsh Lane, Darsham, is closed until Summer 2026 to enable the construction of the Northern Park & Ride roundabout and site. The diversion route in place is via Walpole Road, A144, A12.

Leiston and Theberton

Abbey Lane, Leiston, is closed until 6 July 2026 to enable the construction of the new railway line. Diversions are in place via Harrow Lane, Hawthorn Road and Pretty Road.

The level crossing between Saxmundham Road and Buckleswood Lane will be closed from 6am Monday 8 June to 6pm Monday 20 July. The diversion route will be B1119, B1122, Westward Ho, Buckleswood Road, Buckleswood Lane and vice versa.

Moat Road and George Road are closed from 26 May to 7 August 2026 for works associated with the Sizewell Link Road. Diversion route will be B1122 and Pretty Road. Following the closure of Pretty Road, the diversion route will be Harrow Lane, Abbey Lane and B1122.

Pretty Road will be closed from 6 July 2026 to 20 August 2027 for the construction of an overbridge as part of the Sizewell Link Road. The diversion route will be Harrow Lane, Abbey Lane and B1122.

Lover’s Lane and the northern access to The Common / Sandy Lane will be closed between 8pm-5am from 15 June to 4 July for the laying of a cable underneath the road. The diversion route is King George’s Avenue and B1122.

The Common will be closed from 26 June to 25 July. Access to properties will be maintained.

Middleton-cum-Fordley

Littlemoor Road, Middleton, closed from 19 November 2025 and is not expected to be reopened.

Friday Street, Benhall

Kettles Lane, Benhall, is closed until Summer 2026 for the construction of the Friday Street roundabout.

Farnham 

Hill Farm Road will be fully closed from 12 January 2026 for works associated with the two-village bypass. The diversion route is A12, Tinker Brook Lane, Station Road and Langham Road.

Chapel Road will be closed overnight (8pm to 6am) as part of Essex and Suffolk Water mains diversion works from 3 July to 21 July. The diversion route is Hall Road, Mill Lane, Great Glemham Road, Main Road and vice versa.

Marlesford – local roads

Marlesford Road (north of the A12) will be fully closed for approx. 130 metres from the A12 junction from 1 June to 1 August. Diversion route will be Marlesford Road, B1116 The Street and vice versa.

Bell Lane will be closed from 25 June to 1 August (8pm-5am) and 5 August-20 August (9pm-6am). Diversion route will be via New Road, Keeper’s Lane, A12 and vice versa.

Ashe Road (south of the A12, aka Marlesford Road) will be fully closed for approx. 130 metres from the A12 junction from 27 July to 7 September. Diversion route will be Hacheston Road, B1078 and vice versa.

Further closures related to the schemes are being progressed through discussions with Suffolk County Council and will be communicated once approved.

Traffic Management

Leiston

Ongoing traffic signals on Lover’s Lane and B1122 Abbey Road.

From 20 July to 7 August traffic lights will be in place on Buckleswood Road.

The A12

On the A12, at Friday Street, varying traffic management is in place, including lane closures and traffic signals until Summer 2026 as part of construction of the new roundabout.

Traffic lights will be in place nightly (7pm to 5am) on the A12 at Marlesford from 25 June to 20 August.

Speed restrictions

A12 between Little Glemham and Benhall: a 30mph speed limit in place whilst works are carried out to construct the new by-pass.

A12 Friday Street: a 30mph speed limit in place whilst works are carried out to construct the new roundabout.

A12 between Kelsale and Yoxford: a 30mph speed limit in place whilst works are carried out to construct the Sizewell Link Road and roundabout.

A12 Darsham: a 30mph speed limit in place whilst works are carried out to construct the Northern Park & Ride roundabout.

B1122, Lover’s Lane and Sizewell Gap: a 30mph speed limit in place.

Buckleswood Road and Westward Ho, Leiston: 30 mph speed limits are in place whilst works are carried out to construct the Green Rail Route.

B1125: 30mph and 50mph speed limits are in place associated with the speed cameras.

Eastbridge Road: 30mph speed restrictions are in place whilst works are carried out to construct the Sizewell Link Road.

Sizewell Gap: 30mph speed limit on Sizewell Gap up to Sizewell Haul Road.