Talk:Friarton Bridge

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[edit] M85 to M90 renumbering

I think there is an error in the descriptionof the renumbering form A85 to A90. Motorway numbering systems are separate and distinct form A and B road numbers. Though the number cones often overlap, it does not follow exactly that an M road will inherit it's number form a A road.

It is more likely that the road was renumbered with the creation of the M9. This will have created the M road cone for the number 9 that would not have existed previously. Thus any M8x roads origonating in the new M9 cone area would be renumbered M9x. The A road numbers would not have been changed by this as there has always been a A9 area cone.

For more information on road numbering, reffer to http://www.cbrd.co.uk/roadsfaq/#2

No, I'm fairly well informed that how it is written was what happened; in Scotland certainly, motorways generally take the number of their predecessor A-road; that might even be the hard and fast rule (hence A876/M876 and A898/M898). The M9, to my knowledge, has always been the M9, as it has always followed the route of the A9, infact curtailing it in the process from Corstrophine to Polmont.

So when the change came in the early 1990's for A85 to A90 between Perth (Craigend) and Dundee, the M85 was "eaten up" to provide the M90 route to continue onward to the A90 towards Dundee. CBRD's own M90 page explains this. Erath 15:54, September 5, 2005 (UTC)