page_title: M90 motorway
section_title: Details
hierarchical_section_title: M90 motorway / Details
caption_attribution_description: own photo
context_page_description: The M90 is a motorway in Scotland. It runs from junction 1a of the M9, south of the Queensferry Crossing, to Perth, passing Dunfermline and Kinross on the way. It is the most northerly motorway in the United Kingdom, the northernmost point being a spur into the western suburbs of Perth at Broxden.
  A small part of the M90 was originally numbered as the M85 motorway.
context_section_description: The M90 leaves the east-west M9 in the vicinity of Kirkliston and heads north. The motorway is interrupted by a short stretch of A90 from where the A90 from Edinburgh joins the M90. The road continues as the A90 until it reaches the junction to the south of the Queensferry Crossing - the A90 becomes the M90 again at that point. The crossing opened as part of the motorway on 30 August 2017; the bridge is configured as a D2M and has a speed limit of 70 mph.
  Previously, the M90's most substantial engineering feature was the Friarton Bridge in Perth, a tall concrete pillared structure which traverses the River Tay. The bridge carries eastbound traffic from Broxden towards Dundee and along the Firth of Tay.
  The road constitutes most of the southerly part of the A90 corridor from Edinburgh, through Perth, Dundee and Aberdeen to Peterhead along Scotland's North Sea coast.
  A large part of the northern section of the motorway follows the route of the former main railway line between Perth and Edinburgh via Glenfarg, Kinross and the Forth Bridge, which was closed in 1970 despite this not being recommended by the Beeching report. It is not obvious when first driving along the road but close inspection of the 1:25,000 scale Ordnance Survey maps of the route illustrates this.
  Another unusual feature of the M90 is that the Kinross and Milnathort Bypass, the 8-mile (13 km) section of the M90 between Fruix and Arlary, was the first motorway in Britain to be constructed using unreinforced concrete pavements. Both the south-bound & north-bound Carriageways have since been overlaid by tarmac. The use of Unreinforced Concrete Paving on Carriageways in Scotland is now very rare. 
  Near to its northern terminus, the motorway splits into two branches. The construction of this three-way interchange required the removal of about 900,000 cubic metres of material, mostly rock. The motorway bends through more than 90 degrees, on a compound curve partly of 520.8 m and partly of 694.5 m radius. One branch heads in a north-easterly direction, flowing into the A90 at its end, numbered junction 11. (This branch was formerly the M85 motorway, until the A85 was renumbered as A90.) The other branch forms part of the western bypass of Perth, and meets the A9 at its end, numbered junction 12. The gradient is 4.57% uphill and 5.65% downhill on this section. The slip roads forming this branch merge with shared priority to allow HGVs to maintain momentum on the steep upgrade. The Broxden to Muirmont slip road at the centre of the interchange has a radius of 136.4 m, necessitating maximum superelevation of 7%.
  The M90 forms part of the Euroroute E15 which runs from Inverness to Algeciras, but which is not signposted within the UK.
caption: M90, North of Kelty at the boundary between Fife and Perth and Kinross
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