Speed limits - how they are set

If you are concerned about traffic speed in your area, you can ask for a reduced speed limit to be put in place. Excessive speed is a major factor in road collisions and fatalities in Northern Ireland, particularly in areas where vehicles and more vulnerable road users mix.

Speed limits 

Speed limits are important and are set to make sure that vehicles travel at a speed suitable for the road.

Speed limits can be adopted for safety, environmental and accessibility reasons.

Department for Infrastructure (DfI) Roads, as the sole road authority for all public roads in Northern Ireland, is responsible for introducing local speed limits where ational limits are not suitable.

Comprehensive information on the speed limits you would expect to come across on the different categories of road is given in chart form in the Highway Code.

Getting a local speed limit changed

If you would like a speed limit to be lowered, raised or extended, you should contact your local DfI Roads Division Traffic Section who will make an assessment.

DfI Roads will seek a police view on any proposed changes to a speed limit.

All characteristics of the road, such as its alignment, the level of activity alongside the road, the collision record, and how a community can be separated by the speed of vehicles, will be taken into account. 

Before deciding to change an existing speed limit, local traffic managers must consider all the relevant factors, including:

  • collision and casualty savings
  • improvement to the environment
  • improvement in conditions and facilities for vulnerable road users
  • reducing public anxiety
  • increased journey times for motorised traffic
  • costs of implementation
  • costs of engineering measures and their maintenance
  • negative environmental impact of engineering measures
  • costs of enforcement

If it is considered that a change in the speed limit is the best course of action, then a Speed Limit Order has to be made. This involves a statutory legal process.

If you wish to report a vandalised/ missing speed limit sign, you should do so online at this link:

Or you can contact the proper division or local DfI Roads office with full details about the location of the sign.

If the road in question has a system of street lighting, with no speed limit repeater signs, the limit is usually 30mph. DfI Roads is not permitted to place 30mph repeater signs on these roads.

The system of street lighting in an area should be enough evidence of 30mph limit.

More useful links

Share this page


Your comments are anonymous and can’t be responded to - if you would like a reply, use the feedback form.

Your comments
Plain text only, 750 characters maximum. Don't include personal or financial information.