Today marks the 20th anniversary of the metrication of speed limits in the Republic of Ireland. 20 January 2005 was the day that all speed limits in Ireland switched from mph to km/h.

The following summary of events is reproduced from our main website:

The Republic of Ireland’s metrication programme started much later than that of the UK. However by completing the metrication of its roads in January 2005, it has left the UK well behind.

In contrast to Canada, which started its conversion programme with speed limits, Ireland made changes of speed limits the final stage in the changeover.

Ireland replaced imperial distance signage over a period of 10 years. Since the lifetime of most road signs is also 10 years this meant that there was virtually no cost to this conversion.

The final stage of the programme was to convert the speed limits on 20 January 2005. The Irish Department of Transport took the opportunity afforded by metric conversion to comprehensively review speed limits. As a result, the speed limits should be better tuned to local traffic conditions and hence helping road safety.

The key to a successful changeover was believed to be a very rapid conversion of the actual signs preceded by a blitz of information and publicity in the two weeks preceding the change. Drivers were therefore left in no doubt as to what was happening and were warned that ignorance or confusion about the new limits would not be accepted by the police as an excuse for breaking the new limits.

Like Australia and Canada, the changeover passed without incident.

“Traffic signs to indicate speed limits in kilometres per hour instead of miles per hour.”
Road Sign Review 2004

“Motorists in Ireland adapt to the introduction of speed limits set in kilometres per hour rather than miles.”
Mind Your Metric Speed 2005

UKMA Newsletter – Volume 3 Issue 1, February 2005

Metric signs ahead – A report by the UK Metric Association by Robin Paice, 2006 (Ireland, page 55) – ISBN 978-0-9552351-0-8

Eight years after the Traffic Signs Regulations and General Directions (TSRGD) were updated to require all new vehicle restriction signs to show vehicle width and height restrictions in both metric and imperial units, the Department for Transport’s Traffic Signs Manual (TSM) has still not been fully updated to take account of the fact that new imperial-only vehicle restriction signs are no longer authorised.

Whilst most other chapters of the Traffic Signs Manual have been updated since 2016, Chapter 8 Part 1 has not been updated since 2009. It includes diagrams for both imperial-only width and imperial-only height restriction signs for use in road works and temporary situations – signs which were legal back in 2009, but have not been authorised for new sign installations since 2016.

Vehicle restriction signs included in the current TSM – Chapter 8 Part 1, page 98

The Traffic Signs Manual contains guidance for traffic authorities on the use of traffic signs and road markings. By failing to fully update it in a timely manner, the Department for Transport stands open to the accusation that they have been promoting the use of unauthorised imperial-only road signs for the last 8 years.

click on the image to access the pdf

The diagram for weight restriction signs is also obsolete as it includes the now unauthorised upper case “T” symbol to represent tonne. The diagram for this sign was corrected to show the lower case “t” in the 2011 amendment to the TSRGD.

Vehicle restriction signs in the current TSRGD

Whilst diagrams in publications for the general public, such as The Highway Code and Know Your Traffic Signs, were updated long ago, it is inexplicable that guidance for authorities that install road signs should not also have been updated.

UKMA would be interested to hear from readers of any cases that they might be aware of in their area where imperial-only restriction signs have been installed since 2016, and would encourage writing to the relevant highway authority asking for such signs to be replaced with legal dual-unit signs in order to avoid possible legal ramifications.