The Friarton Bridge is a steel box girder bridge with a concrete deck, across the River Tay on the southeastern outskirts of Perth, Scotland, approximately 20 miles upstream of the Tay Road Bridge. The bridle was constructed by the Cleveland Bridge and Engineering Company with Miller Groupas the foundation and concrete sub-contractor. The bridge was designed by Freeman Fox and Partners with the team being led by Dr Oleg Kerensky CBE, DSc, BSc, FRS, FEng, FIStructE,FICE and the resident engineer was H Binnie. The site manager for Cleveland was J Robinson and for Miller it was R Gormley.The bridge was a pair of steel box girders (one under each carriage way) 4.3 m wide overlaid by a lightweight concrete deck. The bridge is 831m long with a river span of 174m. The river span provided a 25m head room for a width of 46m of the 76m wide navigation channel. The boxes vary in depth between 2.7m and 7.5m, with the deeper section located close to the river. It forms part of the eastern spur of the M90 between junctions 10 (Craigend) and 11 (Broxden), the most northerly motorway junction in the UK. It also forms part of the important east coast road corridor from Edinburgh through to Dundee and Aberdeen. It is the single largest structure on the M90, a title it will hold until the completion of the second Forth Road Bridge in 2016. It was the first large box girder bridge to be build to the Merrison Rules which were introduced in 1973 after the collapse during construction of three box girder bridges during the 1970s. The bridge was strengthened during the 2000s to cope with modern traffic loadings.
It is a two-lane dual carriageway; unusually for a motorway (although not unusually for the M90) neither carriageway has a hard shoulder. When it was built in 1978, it was designated as the M85 motorway. When the A85 from the north end of the bridge to Dundee was renumbered in the early 1990s to A90 through to Dundee, the motorway's designation changed to M90 to provide a continuous route number from Edinburgh through to Fraserburgh.