Risk of grounding sign: what it means
The risk of grounding sign warns that long, low vehicles could get stuck on a hump in the road, such as at a level crossing.
What does the risk of grounding sign mean?
Know your traffic signs says long low vehicles may be at risk of grounding, and drivers of such vehicles must phone before crossing. The symbol shows a low trailer caught on the hump.
Quick quiz
What does the sign at the top of this page mean?
- A humped bridge ahead.
- Long, low vehicles may get stuck on the crossing.
- Large or slow vehicles must phone before crossing.
Show answer
B. Long, low vehicles may get stuck on the crossing. It warns that long low vehicles may ground on the crossing (Know your traffic signs). Source: Know your traffic signs: level crossing signs and signals, GOV.UK; The Highway Code, rule 294, GOV.UK; Traffic sign images, Department for Transport, GOV.UK
Where will you see it?
Before level crossings and humped bridges where the road rises sharply.
What should you do?
Drivers of long, low vehicles: follow the signs and phone for permission before crossing. Car drivers can usually carry on with care.
What do people get wrong?
Thinking it is about the road being slippery. It is about vehicles catching on the hump.
Common questions
Which vehicles are at risk?
Long vehicles with low ground clearance, such as low loaders.
What must their drivers do at a level crossing?
Phone before crossing, as rule 294 and the signs say.
Compare with
Hump bridge signA humped bridge ahead.
Phone before crossing signLarge or slow vehicles must phone before crossing.
Want to test someone else? Play a road-sign quiz with friends and family.
Sources
Checked on 4 November 2026 against Know your traffic signs (level crossing signs and signals) and The Highway Code rule 294.
- Know your traffic signs: level crossing signs and signals, GOV.UK
- The Highway Code, rule 294, GOV.UK
- Traffic sign images, Department for Transport, GOV.UK
Contains public sector information licensed under the Open Government Licence v3.0. Traffic sign images are Crown copyright, from the Department for Transport. Sources and image credits.