Traffic was queued back as far as Dumbarton Town Centre after a “one car collision” on the A82 Alexandria by-pass to Loch Lomond.
Motorists were told that delays could be as long as one hour.
Later this statement was issuede by Police Scotland:
Appeal for information following crash on the A82
Road Policing officers are appealing for information following a one vehicle crash on the A82.
Around 3.05pm on Monday, 18 August, 2025, we received a report of a car crashing into a barrier on the northbound carriageway of the Renton bypass, around one mile south of Stoneymollen roundabout.
Emergency services attended and a 49-year-old man was taken to Queen Elizabeth University Hospital in Glasgow.
Word on te ground locally was that the driver, who had to be cut out of his, had suffered a heart attack.
The road was closed to allow police inquiries to be carried out and re-opened around 6.30pm.
Sergeant Scott Miller: “We continue to carry out inquiries to establish the full circumstances of the crash and the events leading up to it.
“We are keen to speak to anyone who witnessed the crash or who saw the Vauxhall Astra being driven in the area prior to the collision.
“I would also urge anyone with dash-cam footage or any other information that could assist to contact police.”
Anyone with any information is asked to contact 101 quoting reference 2189 of 18 August, 2025.