On a smart motorway you first pass an overhead gantry signal showing a white diagonal arrow pointing from your lane into the next lane. About half a mile further on, another gantry shows a red X directly above your own lane. Under Highway Code Rule 258, what is the legal difference between what these two signals require of you?
- Both are legally binding instructions: the diagonal arrow requires you to move into the lane shown in good time before the closure, while the red X marks the point beyond which you must not drive in that lane at all
- Only the red X is legally binding; the diagonal arrow is a courtesy suggestion that a driver may disregard if the road ahead looks clear
- Both signals mean exactly the same thing, and the diagonal arrow is simply an older sign design that is gradually being replaced everywhere by the red X
- The diagonal arrow applies only to lorries and coaches merging early for a weighbridge, while the red X applies to every vehicle in the lane
Why A? And why not the others?
Correct answer: A. Both are legally binding instructions: the diagonal arrow requires you to move into the lane shown in good time before the closure, while the red X marks the point beyond which you must not drive in that lane at all
Rule 258 of the Highway Code makes both signals mandatory rather than advisory. The advance signal showing a white diagonal arrow instructs drivers that they must follow the instruction and move safely into the lane indicated in good time, before reaching the closure itself. The sign showing a red X directly above a lane marks the closure point itself: from that gantry onward drivers must not drive in that lane under any circumstances, regardless of how clear it appears. Treating the advance arrow as optional misses that Highway Code motorway signals use 'MUST' for both stages, not just the final closure; the difference between the two signals is timing and function (move over in advance versus the lane is now closed), not which one is enforceable. The suggestion that the arrow is a phased-out older design, or that it is restricted to particular vehicle types such as lorries or coaches merging for a weighbridge, has no basis in the Highway Code; both apply to all vehicles using the motorway.
Source: Highway Code Rule 258, Motorway signals (GOV.UK)