A470 southbound closes overnight at Pontypridd on 9, 10 and 11 September

Resurfacing between Pontypridd and Upper Boat is scheduled from 20:00 to 06:00 each night, with the final reopening at 06:00 on Saturday 12 September. Traffic Wales gives no diversion route, so drivers must follow the signs.

Louise Pryce · Wed 9 Sept, 17:22 · updated Thu 10 Sept, 04:23

Archive article. Published on Wed 9 Sept, 17:22. Conditions may have changed since this reporting.

The A470 at Pontypridd, with a footbridge crossing the dual carriageway. Photo: David Smith, CC BY-SA 2.0, via Geograph (geograph.org.uk/photo/7302991) and Wikimedia Commons

Original photograph CC BY-SA 2.0

The A470 southbound is scheduled to close between Pontypridd and Upper Boat from 20:00 on Wednesday 9 September until 06:00 on Thursday 10 September, and at the same hours on 10 and 11 September. Traffic Wales, the Welsh Government's traffic information service, calls the work resurfacing and dates it 9 to 12 September, so the final reopening is scheduled at 06:00 on Saturday. The whole carriageway goes: the alert says Road closed, not the lane closed or slip road closed wording Traffic Wales uses on the lesser entries on 9 September. Traffic Wales lists no northbound closure on this stretch. It names no diversion route either. It prints the word Diversion in the alert title and nothing after it: no roads, no distance, no estimate of added journey time. Drivers follow the signs, and Traffic Wales takes calls on 0300 123 1213.

The Welsh trunk road board, read at 16:56 on 9 September 2026

3 figures

A470 southbound, Pontypridd to Upper BoatTraffic Wales lists a full southbound closure for resurfacing on the nights of 9, 10 and 11 September, ending at 06:00 on 12 September.: 20:00 to 06:00
Trunk road closures in force overnight in WalesOf the 14 overnight roadworks alerts on the board, seven shut a road outright. Two of the seven sit on the same A4060 junction above Merthyr and are filed separately, one for surveys and one for roadworks.: 7
Alerts on the A470 and the M4That is half of the 24 on the whole board, split between two roads. The A55 carries three, the A465, the A4060 and the A40 two each, the A487 and the A4232 one each, and one alert names no road at all.: 6 each

Source: Traffic Wales road traffic alerts, board and alert pages

This is the length of the A470 that runs down from Pontypridd to the M4 at junction 32 Coryton and on into Cardiff, and the route the road carries south from Merthyr. Traffic Wales gives one map pin for the closure and no junctions at either end, so exactly where it starts and stops is not published. One other A470 closure runs on the same hours a little further south: the northbound exit slip at Nantgarw, shut nightly from 20:00 to 06:00 until 19 September. Traffic Wales does not say how the two work together.

Five more roads shut overnight

Eighteen roadworks alerts were listed across the Welsh trunk road network when Cover checked the board on 9 September and 14 of the 18 run on overnight hours. Seven of the 14 shut a road outright, the A470 among the seven, though two of those seven sit on the same A4060 junction above Merthyr, on identical dates and hours, one filed for surveys and one for roadworks. The others are the A470 at Ty-Gwyn east of Builth Wells, the A487 at Llanrhystud on night three of eleven, the A40 northbound between the A449 interchange and Monmouth's Dixton roundabout, and the M4 eastbound through the Brynglas tunnels at Newport, on 9 and 10 September. In north Wales the eastbound bore of the A55 Conwy tunnel closes from 19:00 to 07:00 behind a contraflow, so that road stays open, and the A55 westbound onslip at junction 35 Dobs Hill shuts from 19:00 to 06:00.

The A40 at Monmouth is open again, southbound at least

Traffic Wales had the A40 southbound between Monmouth's Dixton roundabout and the Gibraltar tunnels down as an overnight closure, which Cover reported on 8 September. The entry as checked on 9 September was published at 10:26 on 9 September and reads one lane closed, at moderate severity, with no reason given for the change. The northbound carriageway on the same road is still shut overnight.

Background and supporting figures

Where this sits

3 checked facts

Is this normal?
- Fourteen of the 18 roadworks alerts in force on the night of 9 September run on overnight hours, between 19:00 or 20:00 and 06:00 or 07:00.
  traffic.wales
How does it compare?
- It runs three nights, 9 to 12 September on the alert's own dates, reopening for the last time at 06:00 on Saturday 12 September.
  traffic.wales
- The A470 and the M4 carry six alerts each on the night of 9 September, half of the 24 on the whole Welsh trunk road board between two roads.
  traffic.wales

Every line above was checked against the source named beside it before this piece was published.

Traffic Wales road traffic alerts, the only source for this piece. Board read page by page at 16:52 on 9 September 2026, 24 entries across three pages, the individual alert pages at 16:54, the board re-read at 16:56 and every id re-checked title by title at 17:01. Alert 594113, for the A470 southbound closure between Pontypridd and Upper Boat, reference RNMDA_2026131614, first published and last updated 04/09/2026 12:58. Alert 594115 for the A470 northbound exit slip at Nantgarw, 594035 for the A470 at Ty-Gwyn east of Builth Wells, 594036 for the A487 at Llanrhystud, 594105 for the A40 northbound at Monmouth, 594109 and 594158 for the two A4060 entries at the A4102 junction, and 594118 for the M4 eastbound bore at Brynglas. Alert 594078 for the A55 eastbound Conwy tunnel bore and its contraflow, and 594127 for the A55 westbound onslip at junction 35 Dobs Hill. Alert 594104 for the A40 southbound at Monmouth, whose entry now reads one lane closed at moderate severity and carries a first published and last updated stamp of 09/09/2026 10:26. Alert 594033 read to establish that the severity field is a bucket label rather than a per-alert judgement. Traffic Wales phone number from the site header. Nothing on the Traffic Wales news page and nothing in the Welsh Government announcements feed, concerns these works. Clarification, 10 September 2026: relative dates in the headline and copy have been replaced with calendar dates. The wider board counts describe the 9 September snapshot, not a fresh network-wide check. Alert 594113 was reopened on 10 September and still gives 9 to 12 September, 20:00 to 06:00; its last-updated field now reads 9 September at 20:00.

Sources: traffic.walestraffic.walesgov.wales

How we verified this(12)

Every closure was read from Traffic Wales' own alert pages as well as the board, and the board was re-read at 16:56 to confirm no alert had changed in between.
The A470 alert is 594113, reference RNMDA_2026131614, first published 4 September 2026 at 12:58 and not updated since. The piece says its window opens tonight, not that the alert appeared tonight.
No diversion route is printed because Traffic Wales prints none: the alert template carries no diversion field at all, and the word Diversion sits inside the alert title with nothing after it.
No junctions are named for the start and end of the closed stretch because Traffic Wales gives one map pin and no geometry, and the piece tells the reader that.
No traffic count is asserted. Neither Traffic Wales nor Rhondda Cynon Taf publishes a flow figure for this stretch, and no off-beat source was used for one. What the road connects is geography, not a measurement.
The counts are 24 alerts on the board, 20 in force tonight, 18 of those roadworks rather than live incidents, 14 overnight, and seven of the 14 shutting a road outright across six distinct stretches, each counted alert by alert from the board.
The A55 eastbound Conwy tunnel closure is not counted among the seven: the bore shuts but a contraflow keeps the route open.
The A40 southbound downgrade is dated to Traffic Wales' own last-updated stamp of 10:26 on 9 September, and no reason is offered because none is published.
Eight alerts Cover listed on 8 September are absent from the 24 on today's board, read title by title across all three pages: 594117, 594112, 594110, 594097, 594032, 594157, 594108 and 593919. Each id also redirects to the board index, but that redirect is what any unknown id returns, so absence from the board is the proof.
The A55 Conwy contraflow is not attributed to a particular bore: the alert says Contraflow and does not name one.
The image is a Geograph photograph of the A470 at Pontypridd taken on 17 September 2022, and its alt text claims no direction, because the photographer's own metadata gives the view as east-northeast from a point about 2.7km north of the closure's map pin.
10 September: replaced relative reader-facing dates with explicit dates, confirmed the A470 schedule on primary alert 594113, and set expiry to the scheduled final reopening. Other road counts remain a dated 9 September snapshot.

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