Start date: 7th of September 2026| End date: 12th of October 2026
Work to carry out essential carriageway resurfacing to a 1.54km section of M4 Junction 32 Coryton roundabout will commence on 07/09/2026 for 25 nights.
The work will be carried out over the 25 nights 20:00 – 06:00 under phased carriageway closures on M4 Junction 32 Coryton Roundabout. The works will be undertaken over 5 separate phases, outlined below:
Details of Restrictions | Start Date and Time** | End Date and Time** | Notes |
Phase 1 – South Eastern Quadrant of Coryton Gyratory Inside and Lane 3
| 20:00 07/09/2026
| 06:00 08/09/2026
| Lane closures only, access maintained through Coryton Roundabout
|
Phase 2 – South Eastern Quadrant of Coryton Gyratory Outside and Lane 2
| 20:00 08/09/2026 | 06:00 09/09/2026 | Lane closures on Coryton RAB 2 Way TTL with convoy system - Switch off Closure of A470 NB Exit slip Closure of A4054 Southbound only |
Phase 3 – South of Coryton Gyratory Inside and Lane 3 (Including lay-by) | 20:00 09/09/2026 | 06:00 10/09/2026 | Lane closures only, access maintained through Coryton Roundabout
|
Phase 4 – South Western Quadrant of Coryton Gyratory Outside and Lane 2 | 20:00 10/09/2026 | 06:00 11/09/2026 | Diversion route provided on M4, turning traffic at M4 Junction 31 |
Phase 5 – South Western Quadrant of Coryton Gyratory Inside and Outside Lane | 20:00 11/09/2026 | 06:00 12/09/2026 | Traffic for Asda and Mcdonald deliveries to be convoyed from entrance point to Longwood Drive
Traffic exiting Longwood drive to be convoyed through closure area. |
Phase 6 – South of Coryton Gyratory Inside and Lane 2 (including access to Longwood Drive) | 20:00 13/09/2026 | 06:00 14/09/2026 |
|
Phase 7 – North of Coryton Gyratory Inside Lane and Lane 2 | 20:00 14/09/2026 | 06:00 15/09/2026 | Alternative access routes will be via a diversion through Tongwynlais |
Phase 8 – North of Coryton Gyratory Outside Lane (including A4054 Lane) | 20:00 15/09/2026 | 06:00 16/09/2026 | Alternative access routes will be via a diversion through Tongwynlais |
Phase 9 – North Eastern Quadrant of Coryton Gyratory Inside and Lane 2 | 20:00 16/09/2026 | 06:00 17/09/2026 | Alternative access routes will be via a diversion through Tongwynlais |
Phase 10 – North Western Quadrant of Coryton Gyratory Outside Lane and M4 EB On-Slip and A470 SB Off-slip | 20:00 17/09/2026 | 06:00 18/09/2026 | Alternative access routes will be via a diversion through Tongwynlais |
Phase 11 – East of Coryton Gyratory Inside and Lane 2 | 20:00 21/09/2026 | 06:00 22/09/2026 | Alternative access routes will be via a diversion through Tongwynlais |
Phase 12 – East of Coryton Gyratory Outside Lane to A470 SB On-slip and A470 NB cut through | 20:00 22/09/2026 | 06:00 23/09/2026 | Alternative access routes will be via a diversion through Tongwynlais |
Phase 13 – East of Coryton Gyratory M4 WB Off-slip including Outside Lane to A470 SB on-slip | 20:00 23/09/2026 | 06:00 24/09/2026 | Alternative access routes will be via a diversion through Tongwynlais |
Phase 14 – North Western Quandrant Outside Lane and A470 NB On-Slip Dedicated lane | 20:00 24/09/2026 | 06:00 25/09/2026 | Closure of A470 NB ENTRY & M4 EB EXIT with 2 way temporary traffic signals convoy working Switch off of existing signals
|
Phase 15 - North Western Quandrant Inside, Lane 2 and A470 NB On-slip | 20:00 25/09/2026 | 06:00 26/09/2026 | Closure of A470 NB ENTRY & M4 EB EXIT with 2 way temporary traffic signals convoy working Switch off of existing signals
|
High Friction Surfacing:
| 20:00 28/09/2026 | 06:00 12/10/2026 |
|
** dates provisional, may be subject to change
Access to residential areas and business premises off the adjacent county side roads has been considered and is planned for each as follows:
· Merthyr Road and Oldfield Road – during Phases 2 and 3, alternative access route will be via diversion through Tongwynlais.
· A4054 Pendwyallt Road – during part of Phase 1, alternative access route from south via diversion from Gabalfa Interchange.
· Longwood Drive – as no alternative access is available, access into and out of Longwood Drive will be maintained throughout the programme except for shift #6 (planned for Sunday 13/09/26) when the gyratory outer lanes across Longwood Drive will be resurfaced. Only emergency access to Longwood Drive will be available during this shift.
For further information, please contact Traffic Wales on 0300 123 1213 or via Twitter @TrafficWalesS