Speed limits on roads
All public roads have speed limits. In most cases, a "default" speed limit applies. This automatically applies to a particular type of road if there is no speed limit sign to show otherwise.
The table below sets down the default speed limits for different roads under the Road Traffic Act 2004.
| Road signal | Type of road | Speed limit |
|---|---|---|
 |
Motorway (Blue Signs - M numbers) | 120Km/h |
 |
National roads (primary and secondary) (Green Signs - N numbers) | 100Km/h |
 |
Non-national roads (regional and local) (White Signs - R or L numbers) | 80Km/h |
 |
Roads in built-up areas, such as cities, towns and boroughs | 50Km/h |
Local authorities can apply special speed limits to these roads, for example:
- at particular times, such as when children are entering or leaving schools (see Respecting other road users section),
- on different sides on a dual carriageway,
- at selected locations such as a tunnel, where the limit may be lowered if one lane must be closed,
- where there is a series of bends, and
- at road works.
If the local authority sets a special speed limit, you will see one of the signs below. Speed limit signs, like most other regulatory signs, have a red border, white background and black numbers and letters. They show the speed in kilometres per hour (km/h). For more information on regulatory and other traffic signs see Traffic signs and road markings section.
30km/hour- 50km/hour
60km/hour- 80km/hour
- 100km/hour
- 120km/hour
The main speed limit signs on national primary and other roads are sometimes followed by small repeater signs to remind you of the road's speed limit.
No vehicle other than fire engines, ambulances or Garda vehicles may exceed the road speed limit at any time.
Periodic speed limits
Normally, speed limits apply 24 hours a day and all year round. In certain situations, local authorities can apply a special speed limit to certain stretches of road for particular periods of time or particular days. Outside these times or days, the usual speed limit at that location is in force.
An example of a periodic speed limit is one used near school grounds. One way to show this special limit is through a standard upright sign with an information plate underneath that shows the periods and days when the speed limit applies.
Another way of showing the speed limit is an electronic speed limit sign which when lit up shows the speed limit in white figures within a red border against a black background. Outside the special speed limit periods, the sign remains blank. Sometimes the electronic sign can be mounted on a grey backing board with two amber lights, which may flash when the sign is lit up.
The sign School Children Crossing Ahead that includes two amber flashing lamps may appear beside periodic speed limit signs to alert you to the presence of school children.
You must not break the periodic speed limits while they are in force.
Checking speed
From time to time and on various stretches of road, Gardaí may use certain equipment to check if vehicles are obeying the speed limit. It is against the law to supply, carry or use any device that can detect or interfere with any speed monitoring equipment under their control.
