Low and weight-restricted bridges

There are some bridges in Northern Ireland which road users should exercise extreme caution when using. These include low bridges and weight restricted bridges. They range from box culvert to large steel structures such as the Foyle Bridge. Interactive maps can help show where these bridges are located.

Interactive map

The interactive map at the following link shows low bridges that require road users to be extremely cautious when travelling under them and weight-restricted bridges:

Low bridges

Each year large vehicles collide with overhead bridges. Such collisions endanger lives as well as cause delays on the road and rail networks. A railway bridge collision could also result in the derailment of a train with potentially disastrous consequences.

An interactive map has been produced to tell drivers of high vehicles, or vehicles with high loads, about bridges with less than 16 feet six inches (5.03 metres) clearance.

Weight-restricted bridges

In order to protect the road network (including bridges) and the safety of road users, weight restrictions will refer to maximum gross weight (MGW), rather than laden or unladen weight and is shown on the interactive map.

Know your signs

The signs below are used to show the maximum headroom of the hazard in both imperial and metric units.

Do not ignore them. 

Maximum headroom road signs

Maximum headroom road signs

Advance warning of a low bridge

Some arch bridges may have a specific headroom over a specific width. This is designated by a white chord on the arch, as shown below.

Advance warning of a low bridge road signs


Black and yellow bands may be added to the arches or girders and parapet walls to improve their visibility. Special road markings may also be used to help guide high vehicles through the highest part of the arch.

Remember these three simple safety rules:

  • know your height
  • know your route
  • know your signs

If you have a long load, remember to take care at bridges where the road curves or dips.

If you have a collision

If your vehicle does collide with a bridge, tell the PSNI immediately and advise the relevant authority.

If it is a railway bridge, Northern Ireland Railways must be informed immediately.

  • phone: 028 9089 9400

Department for Infrastructure (DfI) Roads

Department for Infrastructure (DfI) Roads is the sole road authority in Northern Ireland, responsible for around 5,800 bridges. If you need any further information, contact DfI Roads.

More useful links


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