The M4 westbound shuts through the Brynglas tunnels again tonight, the second and last night of the closure at Newport

The M4 westbound closes tonight through the Brynglas tunnels at Newport, between junction 24 Coldra and junction 28 Tredegar Park, from 20:00 until 06:00. Traffic Wales, the Welsh Government's traffic information service, calls the work maintenance and gives the run as 7 to 9 September on those hours, which is two nights. Last night was the first and tonight is the last. Brynglas is a twin bore tunnel and each bore carries its own alert. The eastbound bore is dated 9 to 11 September, so on the published schedule eastbound traffic through Newport is unaffected tonight and the eastbound closure starts tomorrow. Traffic Wales names no diversion route on either entry. It publishes the word Diversion and nothing after it: no route, no distance, no estimate of added journey time. A driver has the signs on the ground, and Traffic Wales takes calls on 0300 123 1213.

Nine more closures on the same hours

Nine other trunk road closures run overnight tonight on or close to those hours. The M4 loses its exit slip at junction 32 Coryton and its eastbound entry slip at junction 36 Sarn, so drivers can still pass those junctions but cannot leave or join there. The A470 northbound loses its exit slip at Nantgarw, and the A470 southbound shuts between Pentrebach and Abercynon on the last of three nights. The A465 shuts westbound between Neath and Llandarcy, its second and last night. The A4060 southbound shuts on two adjoining stretches around Pentrebach, filed by Traffic Wales as two separate alerts. The two A40 closures at Monmouth, which Cover reported on 5 September, run to the same hours. Each window and each alert number sits in the table below, so a driver can pull up the entry that matters.

The Coryton slip

Traffic Wales labels the Coryton alert Northbound. The M4 at Coryton runs east and west only, and Traffic Wales does not say which carriageway the closing slip serves. A 2024 Welsh Government order for the junction records the eastbound and westbound carriageways as each having a dedicated exit slip on to the A470 northbound, which explains the label but not tonight's slip. Cardiff City host Stoke City at Cardiff City Stadium tonight, kicking off at 19:45. Neither Traffic Wales nor Cardiff City has published anything joining the match to the 20:00 closure.

North and mid Wales tonight

The board runs further north as well, on slightly different hours. The A55 westbound loses a tunnel between junction 17 Conwy Morfa and junction 16A Dwygyfylchi tonight, on the last of three nights, with temporary traffic lights on the stretch, and a second alert holds both directions there to a 3.25 metre width limit with lorries diverted, which bites on vans and anything towing rather than on a car. Both run 19:00 to 07:00. The A470 shuts in both directions at Ty-Gwyn east of Builth Wells on the same hours. The A487 closes in both directions at Llanrhystud and the A458 in both directions between Buttington and the A483 interchange, both of those 19:00 to 06:00, and the A458 ends tonight.

What Traffic Wales has not said

Traffic Wales publishes no diversion route for any of tonight's south Wales closures, so none is printed here: on these entries it gives the word Diversion, or Diversions in place, and never a route. It does not say whether the Coryton exit slip closing at 20:00 serves the eastbound or the westbound M4. And a long entry between the Hardwick roundabout at Abergavenny and Raglan, on which Traffic Wales gives no road number at all, reads bridge closed and local lanes closed and runs to 14 September, yet carries one time value, 0600, rather than a from and to window, so whether that one is nightly or round the clock is not on the page.

Traffic Wales takes calls on 0300 123 1213 and posts on X as @TrafficWalesS in south Wales, @TrafficWalesN in north and mid Wales.