Descending a long, steep hill on a rural A-road, you pass a warning triangle for a steep gradient, then a supplementary plate, then a blue rectangular sign showing a lorry running into a bed of gravel to the left of the main carriageway. What is this last sign warning you about, and which vehicles is it primarily provided for?
- A permanent lay-by where any vehicle may pull in to let faster traffic pass on a single-carriageway road
- An escape lane ahead, a gravel or sand arrester bed for vehicles that cannot stop or control their speed on the descent
- A diversion route for lorries only, because the main road ahead is closed to vehicles over a stated weight
- A weighbridge where loaded lorries must stop to be checked before continuing down the hill
Why B? And why not the others?
Correct answer: B. An escape lane ahead, a gravel or sand arrester bed for vehicles that cannot stop or control their speed on the descent
On a small number of the UK's steepest, longest descents, a sequence of signs, the steep-hill warning triangle, a supplementary plate, and then this blue rectangular sign showing a vehicle running into a bed of loose material, leads up to an escape lane: a gravel- or sand-filled runoff area built into the verge specifically for vehicles (typically heavy lorries and buses, which are far more likely to suffer brake fade or failure on a long descent) that lose the ability to slow down or steer normally. It exists to bring an out-of-control vehicle safely to a stop away from the main carriageway, not to let ordinary traffic pull over, a general-purpose lay-by is a completely different, much more common feature and would not be signed with a vehicle-running-into-gravel symbol. Reading the sign as a weight-restricted diversion or a weighbridge invents a checking or routing function the sign does not have; nothing about the picture or the sequence it appears in relates to a vehicle's stated weight, only to whether the driver can still control the vehicle's speed.
Source: DfT Know Your Traffic Signs — Warning signs (Escape lane, diagram 817.2, GOV.UK); Traffic Signs Manual, Chapter 4: Warning Signs (GOV.UK)