Motorway gantry sign
A gantry spanning the motorway with blue overhead signs indicating one lane exiting and two continuing ahead, and the following text.
Left lane destinations: A4810 Magwyr; Magor; Caldicot .
Right-hand two lanes destinations: London, Bristol M4; Cas-gwent; Chepstow (M48) .
Junction number: 23A.
For some reason the third lane exits here, even though most traffic is staying on the M4. It rejoins us again at the far side of the junction.