M4 Junction 23: Rogiet (M48)
Junction 23 at Rogiet is the first junction in Wales, just over the Prince of Wales Bridge, where the M48 rejoins the M4 from Chepstow. Undy and Magor are close by, and Caldicot is a little under three miles east. Penhow Castle is about two miles north-west.
This is the first junction in Wales, crossed by commuters, holidaymakers and people visiting family on both sides of the border. The map shows how the junction sits between Undy, Magor and the river.
Check this junction now: live M4 speed flow map · latest M4 traffic news · M4 serious incidents · M4 accidents
M4 Junction 23 Now: Accidents, Incidents and Roadworks
Live traffic news at M4 Junction 23
This is the news for Junction 23 only, not the whole M4. For the rest of the motorway see all the latest M4 traffic news, the overhead signs and the speed limits in force now.
Updated 21:29 (9:29pm) Wed 21 Oct 2026
Live Traffic Speeds at M4 Junction 23
The speed strip below shows the M4 around this junction, both directions, from National Highways’ live data, checked every five minutes.
Untick all three to see just the speeds. We show the important overhead signs and the mandatory speed limits (red ring); see every overhead sign.
Go to our live M4 traffic speed flow map ›
NOTE: The speed flow, overhead sign messages or other information shown on our live traffic speed flow map is updated every few minutes. We cross check the data and aim to provide warnings if there could be a delay or an inaccurate speed reading. There can be occasions, beyond our control, and despite our best efforts where the speed flow could be inaccurate. We cannot therefore guarantee the speed you can expect on any stretch of the motorway is always accurately shown. However we hope you will find our live traffic speed flow map a useful tool in trying to plan your journey. Safe driving.
All the latest M4 traffic news →Live M4 traffic speed flow map →
M4 J23 in Our Records
No accidents, breakdowns or obstructions at J23 have reached us in the last 13 days. In both directions, traffic has been running faster than its typical speed, even at the slowest times of day.
Average speed by hour of day at J23
Westbound
Eastbound
Incidents per week at J23
Built from our own records of National Highways’ live data for the M4 either side of J23: speeds from 13 days of five-minute readings, incidents from the last 13 days (we started recording incidents on 09/10/2026). Each incident is counted once. Updated every five minutes.
- Junction M4 J23, Rogiet
- Roads at this junction M48
- Nearest town Caldicot, 2.7 miles east
- Junction before J22, Pilning, about 6.8 miles in a straight line
- Junction after J23A, Magor, about 1.1 miles in a straight line
Around M4 Junction 23: Rogiet: Towns and Places on the Map
| Place | What it is | From the junction |
|---|---|---|
| Penhow Castle | Historic house or castle | About 2 miles north-west |
| Caldicot | Railway station | About 2.5 miles east |
| Whitson Court | Historic house or castle | About 4.5 miles south-west |
