Low Bridge Signs

Low bridge signs warn drivers, especially those in high-sided vehicles, about bridges and other structures with restricted headroom so they can avoid collisions and choose a safe route. This page explains what these low bridge signs mean, how to recognise them quickly, and links to every individual road sign in this category so you can revise them for your car theory test, motorcycle theory test, HGV / LGV theory test, PCV theory test, or ADI Part 1 theory test.

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What are low bridge signs?

Low bridge signs are part of the UK road and traffic sign system used to give drivers and riders clear warnings about bridges, tunnels and other structures with limited headroom. They help you understand the maximum vehicle height allowed, when you must not pass under a bridge, and when you should follow an alternative route, so you can plan your journey safely and confidently.

You'll usually see:

  • Height restriction warning signs in advance of a low bridge, showing the maximum vehicle height permitted.
  • Low bridge restriction signs at the bridge confirming the height limit and where high-sided vehicles must not pass.
  • Additional information plates and diversion signs giving alternative routes for vehicles over the height restriction.

Understanding these low bridge signs is essential if you drive larger vehicles such as vans, HGVs or PCVs, or tow tall loads - and they can all appear in your DVSA driving theory test and hazard perception test.

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Whether you still need to book your UK theory test or you're focusing on extra revision on low bridge signs and the rest of the DVSA theory test syllabus, pick the option that best matches your DVSA theory test journey.

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Already booked your DVSA theory test and just need to revise? Get started with Driving Theory 4 All's AI-powered theory test app and online Learning Zone to revise the latest DVSA material and all UK road signs, including low bridge signs.

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Essential low bridge signs you need to know for the DVSA theory test

The DVSA driving theory test can include questions about low bridge signs.

When you revise with Driving Theory 4 All, you'll see these low bridge signs along with DVSA revision questions, hazard perception practice clips, and unlimited mock theory tests.

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Use this section to quickly find common low bridge signs in the UK road and traffic sign system. Select a sign to open its dedicated page.

Advance warning of a mandatory height restriction ahead sign

Rectangular - blue Bridge Size restriction Distance to Low bridge signs
View advance warning of a mandatory height restriction ahead sign

Directional sign with alternative route to avoid a low bridge sign

Rectangular - white Size restriction Distance to Alternative route Rectangular - green Low bridge signs
View directional sign with alternative route to avoid a low bridge sign

Location of mandatory height restriction ahead, with indication of an alternative route sign

Rectangular - blue Size restriction Distance to Alternative route Low bridge signs
View location of mandatory height restriction ahead, with indication of an alternative route sign

No vehicles over the height shown may pass the sign

Circular - white with a red border Size restriction Low bridge signs
View no vehicles over the height shown may pass the sign

Reduced headroom over a road due to an overhanging building sign

Triangular Size restriction Low bridge signs
View reduced headroom over a road due to an overhanging building sign

Road works sign showing a height restriction sign

Rectangular - yellow Lane Motorway Size restriction Distance to Low bridge signs
View road works sign showing a height restriction sign

The maximum headroom under a bridge or other overhead obstruction sign

Triangular Size restriction Low bridge signs
View the maximum headroom under a bridge or other overhead obstruction sign

The maximum safe headroom at an arch bridge sign

Triangular Bridge Size restriction Low bridge signs
View the maximum safe headroom at an arch bridge sign

The maximum safe headroom at an arch bridge with supplementing plate sign

Triangular Bridge Size restriction Low bridge signs
View the maximum safe headroom at an arch bridge with supplementing plate sign

View our full UK road signs directory

Previous: Level Crossing Signs and SignalsNext: Miscellaneous Signs

Source: Department for Transport - Know Your Traffic Signs. Contains public sector information licensed under the Open Government Licence v3.0.

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