From Roader's Digest: The SABRE Wiki
|Via:||South Queensferry, Inverkeithing|
|Length:||28.7 miles (46.2 km)|
|Meets:||M9, A90, A823(M), A92(M), A92, A91, A93, A9, A85, A90|
|Former Number(s):||M85, M9|
|Route outline (key)|
The spur to the eastern side of Perth originally held the number M85, and the M90 number was originally used solely for the western spur.
A section of M90 less than 2 miles long, and its even shorter spur the A823(M), were the first motorways in Scotland, opening simultaneously with the non-motorway Forth Road Bridge in September 1964. The section of M90 in question ran from junction 1 to a temporary tie-in at what is today the B981/B916 junction at Duloch. (The B981 was then the A90).
It is the northernmost motorway in the UK.
Forth Replacement Crossing
M90 Southern Extension
The M90 is currently being extended southwards across the Firth of Forth via a new cable-stayed bridge as part of the Forth Replacement Crossing project. As part of this project the existing A90 dual carriageway north of the Forth between Rosyth and Inverkeithing will be upgraded, along with a section south of the Forth between Echline Roundabout and Scotstoun Interchange. The current M9 Spur will also become part of the M90. This means that following the completion of the Forth Replacement Crossing project the M90 will terminate at M9 Junction 1A, south of the Forth.
Intelligent Transport System
Phase 1 of the Forth Replacement Crossing project involved the upgrading of the M90 motorway between Healbeath Junction (J3) and Admiralty (J1). The existing southbound hard shoulder was adapted for use as a bus lane and overhead gantries were installed. These new gantries carry variable message signs which include the ability to set variable mandatory speed limits - an Intelligent Transport System (ITS). This is the first use of variable mandatory speed limits in Scotland. The new ITS was activated on 4th December 2012. Some of the new gantries carry speed cameras which are used to enforce the variable speed limits.
M9 Junction 1A Upgrade
Previously the M9 Junction 1A only had east-facing slip roads. As part of the Forth Replacement Crossing project this junction was upgraded with new west-facing slip roads, opening on 1st February 2013. The east facing slip roads were also widened to return them to their original 2 lane width. (They were narrowed to a single lane previously for safely reasons). The southbound hard shoulder was also upgraded so it can be used as a bus lane, and an ITS system with variable mandatory speed limits was installed.
Main Article: Broxden Roundabout
The Broxden Roundabout is the northernmost motorway junction in the Great Britain. Found in Perth, it is one of Scotland's busiest and most important junctions. The A9 heads north for its journey to Inverness & the far north of Scotland at this roundabout, whilst southbound the A9 is signed for Stirling and Glasgow and the A93 takes the A9's old route though Perth. The M90 spur meanwhile takes traffic to Dundee, Aberdeen or Edinburgh.
Main Article: Kinross services
Kinross services are the most northerly services in Great Britain, being located just off junction 6 of the M90. As befits a relatively quiet motorway, it is a very small single-site MSA.