With the advent of motorway-building in the United Kingdom in the late 1950s, the M8 was planned as one of a core of new motorways, designed to replace the A8 road as a high-capacity alternative for intercity travel. The motorway was constructed piecemeal in several stages bypassing towns, beginning in 1965 with the opening by Minister of State for ScotlandGeorge Willis of the bypass of Harthill. In 1968 the Renfrew Bypass was opened as the A8, becoming part of the M8 when the motorway to the west was connected. The Glasgow inner city section was constructed between 1968 and 1972, using a scheme outlined in the Bruce Report, which was published as the Second World War was closing, and which set out a series of initiatives to regenerate the city. Bruce's scheme evolved into what would become the Glasgow Inner Ring Road, a motorway "box" which would encircle the city centre, connected to the Renfrew Bypass at its south western corner, and the Monkland Motorway towards Edinburgh at its north eastern corner. Together, these three sections of motorway make up the present day M8. Most of the motorway's length was complete by 1980. Since then, there has been a new interchange with the M80 motorway added in 1992, a eastern extension from Newbridge to the then-new Edinburgh City Bypass in 1995, and the new junction on the approach to the Kingston Bridge in Glasgow connecting to the new M74 extension in 2011. As part of the Scottish Government's 'M8 M73 M74 Motorway Improvements programme', on which construction began in early 2015, the remaining unfinished section between Baillieston and Newhouse was built, alongside other major improvements enhancing connectivity to the local road network, M73, and M74. The new section was fully opened on 30 April 2017. On 6 December 2019, the Southbar interchange was reopened to facilitate regeneration in the Bishopton area, having been previously closed during the 1970s.
The M8, more explicitly the Glasgow section, is unusual amongst UK motorways in that it directly serves a large urban area, whereas most other motorways bypass such conurbations. The central Glasgow section is mainly elevated on a concrete viaduct, lowering pollution concentrations but exposing some public spaces, roof terraces and other parts of buildings to noise and shading. From arterial roads are slip roads that enter and exit from the passing lane. It contains one of the busiest river crossings in Europe, Glasgow's Kingston Bridge. The speed limit there is reduced to 50 mph as a result. At least three main nearby incomplete structures have been demolished or reused from the 1960s dubbed Bridges to Nowhere. A few others remain from those works. The root cause of most traffic congestion on the urban section is traffic from the M73 and M80 routes onto the eastern section of M8 which within reduces from five lanes to two on the Kingston Bridge approaches. The result being it is often lengthy. Prior to the construction of the M74 extension, incentives were undertaken in an attempt to minimise delays on this section; these include restricting exits around the Kingston Bridge, a ramp metering programme, and expanded use of electronic signing above and beside the motorway as part of the CITRAC system. The M8 represents a barrier to wildlife expansion, particularly the reintroduced beaver, from the north of Scotland into the Scottish Lowlands, Southern Uplands and Dumfries and Galloway.
Problems solved
Successive failed attempts were made to build the southern flank of the Glasgow Inner Ring Road envisaged by the Bruce Report of the late 1940s. The eastern section had been planned to run north/south close to the High Street of Glasgow, through or under Glasgow Green to the southside of the Clyde. Public opinion was strongly against this and the eastern section was shelved, with a much later M74 connecting the far-eastern areas of Glasgow. This section, which is an extension of the M74 was built to a different route, intended to funnel long-distance traffic from the north and south which is bound for the southern Clyde Coast and allow it to bypass the urban section of the M8. Following many years of intensive political discussion and legal battles, the M74 completion began in 2008 and opened in June 2011. Indications are that the new road has been successful in reducing traffic levels on the urban section of the M8.