A bid for listed status is being launched for the Kingston Bridge as the structure reaches its 50th birthday.
The Glasgow bridge was opened on June 26, 1970 by the Queen Mother after three years of construction and a cost of £11m – the equivalent of £180m today.
Spanning a length of 270 metres, the bridge is over 40 metres wide and 20 metres tall.
Transport secretary Michael Matheson said: “The Kingston Bridge has become an iconic landmark in Glasgow over the half-century it’s been in operation.
“The crossing played its part in taking a significant amount of traffic off the city centre streets and paved the way for the pedestrianisation of Sauchiehall Street, Buchanan Street and Argyle Street.
“There is no doubt it continues to play a vital role, carrying around 155,000 vehicles a day.
“The work that’s been carried out to ensure it continues to do this job in the future has also won civil engineering awards, so applying to have the Kingston Bridge listed seems a fitting way to mark its impact over the past 50 years.”
The Glasgow Motorway Archive in collaboration with Transport Scotland is also releasing a number of previously unseen photos of the Kingston Bridge from the late 1960s and early 1970s.
Stuart Baird, from the Glasgow Motorway Archive, said: “The Kingston Bridge was recognised as one of the most ambitious infrastructure projects ever undertaken in Scotland at the time and it’s had a huge impact in shaping the city over the last five decades.
“Listing the bridge doesn’t simply acknowledge its unique engineering and architectural features, it also recognises the work of the people that designed, built and maintained it over its first half-century of service.
Transport Scotland has applied to Historic Environment Scotland to have the bridge listed as a structure of historic and architectural interest.
Elizabeth McCrone, head of designations at Historic Environment Scotland, said the bridge was not only a key part of Scotland’s motorway, but one of the busiest road bridges in Europe.
Mrs McRone added: “Scotland has a strong heritage of engineering achievements and the Kingston Bridge was designed by W. A. Fairhurst & Partners, one of the leading civil engineering firms of the period.
“We’d love to hear what the people of Scotland think about the proposal to recognise the Kingston Bridge as a listed structure.”