Variable message sign
A gantry structure spanning the road with electronic signals over each lane and a large MS4 message sign on the left.
A 40mph speed limit is shown over all lanes, except the left lane which has a red X. The message "accident" is shown.
The Smart Motorway continues through the countryside towards Reading. We’re now on the long stretch of M4 that opened in 1971 - from junction 8/9 behind us all the way to 18 near Bath was one enormous project.