Photo: Mike Bird / Pexels. Illustrative photograph.
Some UK road signs turn up rarely but still appear in the theory test and on real roads: speed limit repeaters, low bridge height signs, weight and width limits, pedestrian zones, tidal flow lanes and clean air zones. This guide explains what each one means for a car driver in Great Britain, using the Department for Transport’s Know Your Traffic Signs.
Speed limit signs you might misread
| Sign | Meaning |
|---|---|
| White circle with a black diagonal stripe | National speed limit for the type of road and vehicle applies. See UK speed limits. |
| Small speed limit repeater | Reminder of the limit you are in |
| Speed in a red circle at a town or village name sign | Start of the limit at the boundary |
| Speed in a blue circle | Minimum speed. A red diagonal line through it marks the end. |
| Speed on a rectangular plate under a bend warning | Advised maximum speed for the bend, not a legal limit |
| Speed limit sign with a camera symbol | Start of a variable speed limit with enforcement cameras |
| Camera symbol on its own | Speed cameras in use in the area |
| Camera sign with “average speed” | Two cameras measure your average speed between two points |
| 20 mph zone entry sign | Entrance to a 20 mph zone, where you may meet traffic-calming measures |
Repeater rules: why you will not see 30 mph repeaters under street lights
- On a road with street lights (other than a motorway), the limit is 30 mph unless signs say otherwise. In Wales it is 20 mph.
- So 30 mph repeater signs are used only on roads without street lighting.
- National speed limit repeaters are used only on roads with street lighting (other than motorways).
- A camera sign on a lit road with no repeaters tells you the limit is 30 mph. On an unlit road with no repeaters, the national limit applies.
Low bridge signs
Bridges with a clearance under 16 feet 6 inches (about 5 metres) are normally signed. These matter if you drive a van, tow a caravan or carry a roof box.
| Sign | Type | Meaning |
|---|---|---|
| Red circle with a height in metric and imperial | Mandatory | No vehicle over that height may pass. It is unlawful for an overheight vehicle to go past it. |
| Red triangle with a height | Warning | Maximum headroom under the bridge or structure ahead. A plate may give the distance. |
| Arch bridge with two heights | Warning | Headroom differs across the arch. Road markings guide tall vehicles through the highest point. |
| Four amber lights flashing in pairs | Warning | A high vehicle has triggered a sensor on the approach to a bridge at risk of strikes |
At an arch bridge, give way to an oncoming tall vehicle using the middle of the road. Cars may keep left and cross the markings if that lets everyone pass safely.
Weight, width and length limits
| Sign | Meaning | Does it affect a car? |
|---|---|---|
| Red circle with a weight in tonnes (for example 7.5T) | No vehicles over that maximum gross weight | Rarely. Most cars are well under. Check if you tow. |
| Red circle with a lorry and a weight | No goods vehicles over that weight | No |
| Red circle with a width (metric and imperial) | No vehicles over that width | Possibly, for wide vans or with towing mirrors |
| Red circle with a length | No vehicles or combinations over that length | Possibly, if towing |
| “Except for access” plate | Exempts vehicles going to premises on that road with no other route | Read it with the sign above |
For towing weights and sizes, see towing on a car licence.
Pedestrian zone signs
- A zone entry sign with a red-ringed prohibition roundel marks the start of a pedestrian zone. It may show hours (for a part-time zone) and exemptions in a lower panel.
- Yellow panels on the sign mean there are waiting restrictions inside the zone.
- The zone may have no kerbs or yellow lines, so the sign is all you get. Check the times before you enter.
- A variable message sign may change the exemptions through the day.
- A “zone ends” sign has a grey version of the roundel.
Some zones use rising bollards. A red signal means the bollard is up and you must not go on. Do not follow an authorised vehicle through.
Tidal flow lanes
On some busy roads, overhead lane signals change how many lanes run each way.
| Signal above the lane | Meaning |
|---|---|
| Green arrow | Lane open to you |
| White diagonal arrow | Lane closes ahead. Move to the next lane on the left. |
| Red cross | Lane closed to traffic facing the signal |
Direction signs for cyclists and pedestrians
- Blue with a white cycle: cycle route direction. A red patch with a number is a National Cycle Network route; a blue patch is a regional route.
- Blue with a walking figure: pedestrian direction sign.
- Green: public footpath. A yellow waymarker is also a footpath; a blue arrow is a bridleway.
Expect cyclists and walkers crossing or joining the road near these signs.
Miscellaneous signs worth knowing
| Sign | Meaning for drivers |
|---|---|
| “2+” or “3+” car symbol | HOV lane. Only vehicles with that many occupants (and others shown) during its hours. |
| White “C” on red | Road charging, congestion charge or toll |
| White cloud on green with a letter A to D | Clean air zone. Class D can include cars; non-compliant vehicles may have to pay. |
| London ULEZ entry sign | Cars not meeting the emission standard pay a daily charge |
| “LEZ” road marking or sign in Scotland | Low emission zone. Non-compliant vehicles must not be driven in it unless exempt. |
| Driver location sign (motorways and some other roads) | Exact location reference to give in an emergency |
Common questions
Why are there no 30 mph repeater signs?
Because street lights already tell you the limit is 30 mph (20 mph in Wales) unless signs say otherwise. Repeaters for 30 mph are only used on unlit roads.
Is the speed on a bend warning plate a legal limit?
No. A speed on a rectangular plate is the advised maximum. Only a speed in a red circle is a legal limit.
Does a 7.5 tonne weight limit apply to my car?
The sign applies to vehicles over the maximum gross weight shown. Ordinary cars are far lighter, but check the plate: some signs apply only to goods vehicles or exempt access.
What does a blue circle with a number mean?
A minimum speed. You must not go slower unless it is impracticable or unsafe.
Are UK low bridge signs in feet or metres?
Newer signs show both. Some older height restriction signs show imperial only and are replaced when they reach the end of their life.
Related sign guides: regulatory signs, warning signs, direction and information signs, traffic calming and road works signs. Back to the main guide: Learning to Drive in Great Britain.
Sources
- Department for Transport, “Know your traffic signs” (gov.uk), sections: Regulatory signs; Speed limit signs; Low bridge signs; Pedestrian zone signs; Direction signs for cyclists and pedestrians; Tidal flow lane control signs and signals; Miscellaneous signs