Sizewell C related Traffic Management & Road Closures

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

Causeway one.network - Roadworks Map & List View - Sizewell C Works Tracker shows all road works including Non Sizewell C works.

Below are is the list of Sizewell C related works

A12 Closures

Yoxford

The A12 and B1122 (Middleton Road) will be closed from 8pm Friday 15 May to 5am Monday 18 May for works related to the new roundabout.

The A12 diversion route is A14, A140, A143, A146, A12 and vice versa. The B1122 diversion route is B1122, B1069, A1094, A12 and vice versa.

Friday Street

The A12 northbound will be closed from 8pm to 5am on the night of 20 May north of the A1094 to facilitate a switch in the lane guard.  The diversion route will be A1094, B1069, B1122, A12.

The A12 / A1094 will be closed from 8pm to 5am on the nights of the 10 and 11 June 2026 for resurfacing works.

The diversion route 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

There are likely to be further nighttime closures of the A12 and A1094 in July to facilitate resurfacing works. Dates will be communicated when confirmed.

Marlesford

There are likely to be nighttime closures of the A12 at Marlesford in June with the current planned dates as the 1 to 4 June (8pm to 5am).

Further A12 closures at Marlesford are likely to follow in Q3 2026 subject to relevant permissions to being granted.

Darsham 

There are likely to be nighttime closures of the A12 at Darsham in Q3 and Q4 2026 associated with the pedestrian crossing works. Dates will be communicated when confirmed.

B1122 Closures

Leiston

From 8pm Friday 29 May to 5am 1 June the B1122 (Abbey Road) will be closed from Leiston Abbey to just south of Rowley Mews, and Lover’s Lane will be closed from Abbey Road to the Leiston waste recycling centre.

From 8pm 5 June to 5am 8 June and 9pm 12 June to 5am 15 June the B1122 (Abbey Road) will be closed from Potter’s Street to Eastbridge Road, and the western end of Eastbridge Road will also be closed.

Abbey Road (B1122) Diversion: B1122, A12, A1094, and B1069

Lover’s Lane Diversion: King George’s Avenue and B1122 Abbey Road
Eastbridge Road Diversion: Church Lane and Onner’s Lane will have an advisory one-way system to aid traffic flow between Eastbridge and Theberton.

Yoxford to Theberton

The B1122 will be closed for weeknights from 26 May to mid-July for improvements, with the closure moving from the western end of the B1122 to the east. The diversion route is B1122, B1069, A1094, A12, and vice versa. 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

Abbey Lane, Leiston, is closed until 29 June 2026 to enable the construction of the new railway line. Diversions are in place via Harrow Lane, Hawthorn Road and Pretty Road.

Buckleswood Road will be closed from 30 March to 22 May. This is to enable the construction of associated railways works. The diversion route is Buckleswood Lane, B1119 Waterloo Avenue, B1122 Station Road. The works will be followed by traffic signals on Buckleswood Road for 4 weeks.

Buckleswood Lane (just northeast of Saxmundham Road level crossing) will be closed by Essex and Suffolk Water to facilitate works associated with the construction of the Buckleswood Lane level crossing for the Green Rail Route.

Between 26 May and 8 June, works will take place in the following order:

• 3-day full closure 26 May to 28 May
• 2-day full closure 3 June to 4 June
• Closure for 2 nights (8pm-5am) 5 June to 8 June

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 will be closed from 26 May to 7 August 2026 for works associated with the Sizewell Link Road. Diversion route will be B1122 and Pretty Road.

The Green, Knodishall level crossing and a section of The Green in the vicinity of the level crossing will be temporarily closed, to install an under-rail crossing from 28 May to 6 June

The diversion route is Theberton Road, Saxmundham Road, Buckleswood Lane at Saxmundham level crossing, B1119 Saxmundham Road and The Green

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.

Tinker Brook Lane will be closed as part of Essex and Suffolk Water work diversion works in early June 2026.  Dates will be communicated when confirmed.

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.

A140 / B1078

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 15 to 18 May traffic lights will be in place in Leiston at Sylvester Road between 9:00am and 3:00pm.

From 18 to 25 May traffic lights will be in place in Leiston at Seaward Avenue between 9:00am and 3:00pm.

From 20 to 21 May traffic lights will be in place in Leiston at Pacton Chadwick Close between 9:00am and 3:00pm.

Wickham Market

From 14 to 15 May traffic lights will be in place on B1438 Wickham Market on weekdays between 9:00am and 3:00pm.

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 overnight (7pm to 5am) in the Yoxford area from 11 to 21 May (A12 south of roundabout), from 26 to 28 May (A12 north of roundabout) and from 1 to 12 June (B1122), for works associated with the Yoxford roundabout.

From 5 May to 15 May traffic lights will be in place on the A12 at Marlesford and Little Glemham on weekdays between 9:00am and 3:00pm.

From 18 to 19 May traffic lights will be in place on A12 at Darsham between 7:00am and 17:00pm.

A1094

Multi-way traffic signals will be in place at the A1094-B1069 junction from 27 April to 12 June for road improvements.

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.