M4 Between J45 – 46: Maes Y Gwernen Bridge Deck Refurbishment

A full road closure on the M4 Maes Y Gwernen overbridge will be required whilst the works are being carried out. 

This essential work will be carried out over the Summer holidays to reduce impact on Morriston Comprehensive School. 

A full overnight road closure of the M4 carriageway will be required to inspect the underside of the overbridge on the following dates between the hours of 20:00 - 06:00: 

11/08/25 - 13/08/25

Westbound closed between J45 Ynysforgan - J46 Llangyfelach.

Lane 2 closed eastbound. 

13/08/25 - 15/08/25

Eastbound closed between J46 Llangyfelach - J45 Ynysforgan.

Lane 2 closed westbound. 

15/08/25 - 16/08/25

Junction 45 westbound entry slip road closed.

Lane 1 closed in both directions. 

Motorway Traffic Diversion 

North Side of Overbridge: Traffic diverted via Heol Maes Eglwys to Pant Lasau Road, Then join the M4 at Junction 46 (Llangyfelach Interchange). 

South Side of Overbridge: Traffic diverted via Llanllienwen Road, Then join the M4 at Junction 45 (Ynysforgan Interchange). 

Local Traffic Diversion North Side of Overbridge: Traffic diverted via Heol Maes Eglwys to Pant Lasau Road, then join the A48 and A4067 southbound. At the Ynysforgan Interchange, exit via Llanllienwen Road. 

South Side of Overbridge: Traffic diverted via Llanllienwen Road, Then take A4067 southbound to join the A48. Use Pant Lasau Road to reach local destinations on the north side. 

Pedestrians South Side of Overbridge: Pedestrians will be diverted to Maes Y Gwernen Road to use the Morriston hospital footbridge, to connect to Heol Maes Eglwys Road and Rhodfa Fadog Road. 

North Side of Overbridge: Pedestrians will be diverted along Heol Maes Eglwys Road to use the Morriston hospital footbridge, to connect to Heol Y Gwernen Road.

M4 Carriageway Closure Diversion (11/08/25 - 15/08/25)

For further information, please contact Traffic Wales on 0300 123 1213 or via X and Facebook.