This is the third edition of our new M8 series, led by feature writer Marissa MacWhirter, where we take a deep dive into the spine of the central belt.
There is no published estimate of how much congestion costs on the M8.
Built in stages from the 1960s, Scotland’s busiest motorway is starting to give way under the pressure of present traffic volumes. And the consequences of maintaining this vital stretch of infrastructure are impacting commuters and the public purse, raising questions about whether its repairs are being managed properly and whether sections of it should be replaced altogether.
The first stretch, the Harthill bypass, opened in 1964 as a modern dual carriageway across the moor. By March 1968, the 6.5-mile Renfrew Bypass had been completed, later becoming part of the M8. Glasgow’s urban motorway was hot on its heels with Townhead in 1968, the Kingston Bridge in 1970, and Woodside and Charing Cross sections completed by 1972. The Glasgow sections, between Hillington and Baillieston (including the Kingston Bridge), cost around £120 million to build – roughly £1.5 billion in today’s prices. The Kingston Bridge itself accounts for about £180 million of that in today’s money.
Compared to today, mid-century motorway building seems like a bargain. It cost around £35 million to tie the Renfrew Motorway into the Kingston Bridge in the mid-1970s. In 2017, the cost to fill the “missing link” between Baillieston and Newhouse (as part of the M8/M73/M74 Improvement Scheme) came in at around £500 million. The new stretch of motorway promised to bring more than £1 billion in economic benefits and save up to 20 minutes on journeys between Edinburgh and Glasgow.
Transport Scotland’s most recent Road Asset Management Plan and annual accounts show that the entire trunk road network, including the M8, is one of the Scottish Government’s largest infrastructure assets with a gross replacement cost in the region of £20 billion as of 2015. Recent accounts put the depreciated replacement cost in the tens of billions.
While there is no standalone figure for the M8, it is one of the most significant parts of the network. And the bill for holding it together is rising steadily. Transport Scotland has a legal duty to maintain the M8 and other trunk roads, and said that climate change, inflation, and capital cuts were making that harder.
The Woodside Viaducts are a case study in what happens when ageing concrete is met with poor record-keeping and strained budgets. Repairs for the key elevated section of the M8 over Charing Cross, which carries about 150,000 vehicles per day, were originally estimated at around £35 million, and completion was expected by the end of 2023, but the cost quadrupled when early inspections revealed worse deterioration than expected, along with an unexpected sewer. Engineers had to install custom temporary propping systems at 23 different support points, each of which needed a bespoke design because of different ground conditions and column arrangements.
Transport Scotland pointed to regular inspections at Woodside since 2010, ISO-certified asset management and a 6.2% rise in its trunk-road maintenance and operations budget to more than £763 million for 2026/27. Temporary propping at the Woodside Viaducts is expected to cost between £126 million and £152 million and will have a 25-year design life. This will allow temporary lane restrictions to be lifted from this autumn, eastbound and westbound in 2027, while a permanent fix is developed, which still has no cost or programme attached. Early options for the permanent intervention will go on display on February 25, with the public invited to have their say on potential plans.
Transport Scotland points to regular MSP briefings and visits at the Woodside Viaducts, and argues that the project has been closely monitored and managed. Despite this, the outcome is a multi-year contraflow with a nine-figure temporary works bill.
“The M8 is a vital link between Glasgow and Edinburgh, and prolonged congestion and roadworks are understandably a concern for the business community,” said Stuart Patrick, of Glasgow Chamber of Commerce. “While we do not hold specific data on financial impacts, the Connectivity Commission noted back in 2018 that congestion on this route was already an issue.
“Businesses rely on timely information, and the combination of extended repair schedules and limited communication is a source of concern,” he added. “We would expect economic impacts to be carefully considered in the planning of major infrastructure projects; however, we are unsure if this was assessed by Transport Scotland.”
Read more
- What has gone wrong with the M8 and will it ever be fixed?
- The average Glasgow driver loses 86 hours a year on the M8
In the latest budget, trunk roads remain the largest single line item within transport spending at around £1.15 billion for 2026/27 – about double the combined allocation for active travel and other sustainable transport (£378 million) and more than bus support alone (£528 million). But support for public transport overall is at £2.15 billion for bus and rail combined.
Traffic volumes on the M8 are back to 2019 levels, with around 82,500 vehicles per day east of Junction 12 and around 71,000 near Newbridge-Hermiston by 2025 counts. In the same year, Transport Scotland recorded roughly 5,900 incidents (about 16 per day), from breakdowns and debris to collisions and weather.
Glasgow drivers lose around 86 hours per week to rush-hour traffic as of 2025. If you value time at roughly £7-£8 per hour using standard government values of time for commuting, those 86 hours equate to around £600-£700 of lost time per regular driver each year.
In the wake of these economic costs, campaign groups like Replace the M8 have argued that alternatives could be imagined for the M8's Glasgow section. They argue that when the motorway was carved through communities, it entrenched inequality and locked the city into car dependence, while occupying land that could be used for housing, green space and public transport.
Like San Francisco’s Embarcadero Freeway, which was replaced with a surface boulevard for around $100 million, Glasgow’s M8 could be reimagined to reconnect neighbourhoods and free up land, though no one has put a price on this yet.
Marissa MacWhirter is a columnist and feature writer at The Herald, and the editor of The Glasgow Wrap. The newsletter is curated between 5-7am, bringing the best of local news to your inbox each morning without ads, clickbait, or hyperbole. Oh, and it’s free. She can be found on X @marissaamayy1
