[USMA:30269] European directive includes kh/h road signs?

[Ezra Steinberg]

I looked up "metric" in the archives of the Irish Times and came across this article in February about the upcoming change-over to metric speed limit signs:   http://www.ireland.com/newspaper/motoring/2004/0211/1242286904MOT11LEAD.html   The bit that interested me the most was this:   "Metric speed limits are required by a 1980 European Council directive, which said that the use of different measurement systems hindered trade. At the time the Council agreed on a limited transition period."   Can anyone say precisely what this directive states and what the specifics of the limited transition period are? And why can the UK continue to use miles instead of kilometers?   Ezra