Hundreds of motorists were caught in 40-minute gridlock when two stubborn drivers locked into a stand-off beneath a narrow bridge in a row over right of way.
The extraordinary situation was caught on camera by one of the drivers stuck in the queue.
Warning: This video contains language some people may find offensive
A woman in a convertible Mercedes entered the tunnel in Forlease Road, Maidenhead, Berkshire, with a sign at the side of the road clearly stating she had right of way.
But an elderly man - also driving a Mercedes - was also driving through, and told bystanders he was not able to reverse his car back out again as he was worried he might crash.
Tempers quickly flared from those forced to wait - but the woman refused to budge, while the man insisted he could not.
Bystander Brad Haverly, aged 30, was in the middle of moving house to Windsor when he pulled up behind the woman's car on the afternoon of September 17.
He told ITV News the situation had been "ridiculous".
He said he hung back and started filming in case it turned into an insurance incident, as other drivers became increasingly irate at her refusal to move.
"Tempers quite quickly flared up once people established she wasn't going to reverse the car," he added.
"And rightly so - people had appointments to go to, there were a number of people saying they needed to pick their children up from school. People got very frustrated very quickly."
Eventually, other drivers convinced the man to reverse. After a couple of near-misses, Mr Haverly's father intervened and leaned in through the driver's side window, helping him steer back.
"In my opinion, the gentleman shouldn't have been on the road. He just didn't have full control of the car," Mr Haverly said.
"The poor guy was really frightened. And to be honest, whether you're an old man or a young man, if you've got so many people around your car shouting at you, you're probably not going to drive very well anyway."
The woman herself phoned police, he said, so convinced was she that she was right - but unfortunately the issue had been resolved by the time they arrived.
Thames Valley Police spokeswoman Charlotte Redman confirmed officers were called shortly before 3.20pm by a female driver who said she was stuck on Forlease Road because another driver would not back up.
"We understand that the car was moved by others, and the road was clear and running by the time we attended," she said.