GBC
Speed

Kilometres per Hour (km/h)

Modern equivalent

0.621371 miles per hour

The metric road speed standard across most of the world, including the Republic of Ireland since 2005.

Britain retained miles per hour through metrication largely because replacing every road sign in the country was judged too costly and too confusing to attempt. The result is a curious island of imperial measurement: a British driver crossing into the Republic of Ireland moves from a road network signed in miles to one signed in kilometres, the Republic having completed its own changeover in 2005.

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