A call has been made to spell out "where and when" two key south of Scotland routes will be upgraded.
A summit in Stranraer heard from range of groups and individuals about concerns over the A75 and A77.
One lorry driver said they needed to be made safer and that driving them could feel like "Russian Roulette".
The meeting of businesses, campaigners and politicians asked the Scottish and UK governments to deliver on promises to improve the two routes.
TUK Transport Secretary Mark Harper confirmed an £8m funding package to improve the A75 last year.
The Scottish government's Strategic Transport Projects Review has also identified improving the safety, resilience and reliability of the route as a priority.
The A75 and A77 are seen as vital links between the ferry ports at Cairnryan and the rest of the UK.
However, a summit at the North West Castle Hotel - organised by the South West Scotland Transport Alliance (SWSTA) - heard the frustrations of a range of bodies over the time being taken to improve them.
Andy Kane, regional ports operations manager for Stena Line, said: "We are in a better place now, with progress towards improvement works, particularly on the A75, but there is still a lot to do.
"The full potential of south-west Scotland cannot be unlocked until these roads are upgraded."
Laura Gilmour, Irish Sea ports director for P&O, agreed that a timetable for upgrades was essential.
"The A75 and A77 are two of the five slowest A-roads in Scotland - they can be made safer, greener and more fit for 21st Century needs," she said.
Lorry driver Steven Wylie, of Dumfries, spends hours every week on the A75 for haulage firm Manfreight.
"This road certainly isn't designed for the amount of traffic that's using it nowadays," he said.
"That's why it needs the money spent on improving it, upping the speed limit for HGVs as well, making it a smoother, faster route.
"Everything is time in this job."
He added that any accidents on the route meant you were "pretty much stuck".
Fiona Barnes, a driver with McBurney's, regularly hauls loads along the A75 and A77 for drop-offs at P&O Ferries in Cairnryan.
She said: "These roads have to become more HGV-friendly - they need investment.
"It will make everything safer for everybody.
"Travel times will be better, so it's going to cut down on the tailbacks because driving along these roads can be like a game of Russian Roulette."
Council leaders in Dumfries and Galloway and South Ayrshire joined the calls for the UK and Scottish governments to "get around the table" and unlock the "massive potential" in improving the routes.
Transport Scotland said the Scottish government recognised the importance of the routes and the "critical link" they provided with markets in the UK and the rest of Europe.
A statement said a series of targeted improvements had been identified in both the A75 and A77 over the next 20 years.
It highlighted significant investment which had already been made and added that while transport was a devolved matter it looked forward to working with the UK government to secure further support.