M3 Lagan Bridge closures to bring weekend disruption for drivers in Belfast

Motorists travelling through Belfast are being warned to allow extra time over the next three weekends as major maintenance work on the M3 Lagan Bridge brings slip-road closures, lane restrictions and lengthy diversions.

The first restrictions begin at 9pm tomorrow, Friday 14 August, and remain in place until 6am on Monday 17 August, with drivers heading from the Sydenham Bypass towards the Westlink, north Belfast and west Belfast among those affected.

Further weekend closures are planned from 21–24 August and 28–31 August.

First closures begin Friday night

During this weekend’s work, the M3 Middlepath Street westbound on-slip will be closed from 9pm on Friday until 6am on Monday.

Anyone attempting to join the M3 from the city centre will instead be diverted via:

A2 Middlepath Street → A2 Bridge End → A2 Ann Street → A2 Victoria Street → A2 Dunbar Link → A2 Great Patrick Street → A2 York Street.

There will also be a closure of lanes one and two westbound, with no access to or from the M3 Nelson Street westbound off-slip towards the A12 Westlink.

That restriction could have a particularly significant impact on motorists travelling from the Sydenham Bypass towards the Westlink or north and west Belfast.

Those drivers will be unable to leave the motorway at Nelson Street and will instead have to continue to M2 Junction 1 at Fortwilliam, before being redirected onto the M2 southbound towards Nelson Street to continue their journey.

Three weekends of disruption

The restrictions are required as six bridge bearings are replaced on the M3, continuing a programme of essential maintenance which began two years ago.

Ten bearings were replaced during summer 2024 at a cost of £700,000, followed by another eight in 2025 at a cost of £400,000.

The latest phase will take place across three consecutive weekends.

On the second weekend, from 9pm on Friday 21 August until 6am on Monday 24 August, work switches to the eastbound carriageway.

The M3 Nelson Street eastbound on-slip will be closed, with traffic diverted via:

A2 Nelson Street → A2 Dunbar Link → A2 Victoria Street → A2 Waring Street → A2 Albert Square → A2 Donegall Quay → A2 Queen Elizabeth Bridge → A2 Middlepath Street.

Westbound restrictions return at end of August

The third phase will affect the westbound carriageway from Friday 28 August until 6am on Monday 31 August.

The M3 Middlepath Street westbound on-slip will again be closed, with motorists from the city centre following the same diversion through Bridge End, Ann Street, Victoria Street, Dunbar Link, Great Patrick Street and York Street.

Lanes one and two westbound will also close again, preventing access to or from the Nelson Street off-slip towards the A12 Westlink.

Drivers arriving on the M3 from the Sydenham Bypass and travelling towards the Westlink or north and west Belfast will therefore again have to continue to the Fortwilliam junction before returning southbound on the M2.

Airport and port passengers urged to plan ahead

The Department for Infrastructure says the work has deliberately been scheduled for summer weekends, when traffic volumes are generally lower.

However, delays are still expected and motorists are being advised to allow additional travelling time — particularly anyone heading to Belfast’s ports or airports.

Diversion routes will be signposted on approaches to the closures, and drivers are being asked to follow temporary traffic management arrangements for the safety of road users and workers.

The work is subject to favourable weather conditions.

The bearing replacement programme is being carried out by Highway Management (City) Ltd under its Design, Build, Finance and Operate contract, with Ekspan Ltd acting as the main contractor.

Following the six replacements this month, further M3 bridge bearings are planned to be replaced during summer 2027.