A driver and 32 pensioners from Thornaby-on-Tees died in 1975 when the coach taking them for a day trip to Grassington organised by their town's mayoress lost control at Dibbles Bridge, a notorious descent between Greenhow and Hebden in the Yorkshire Dales.
Only 13 of the 45 women in the party survived after the vehicle's brakes failed on the steep downhill section and the coach smashed through a barrier, landing on its roof in the garden of a cottage.
The death toll makes it Britain's worst road accident and it devastated the town of Thornaby, where all of the victims had lived - its impact being less only than the toll of the two world wars.
Since the accident, there has been no plaque or other memorial at Dibbles Bridge, where seven people were killed on a coach outing from York to Bolton Abbey in 1925 in similar circumstances.
On May 27, the 47th anniversary, a memorial will be dedicated at Thornaby Town Hall - having been made from stone quarried from Hanson's at Greenhow Hill, close to the crash site.
It will display the names of all 33 victims and has been funded by the town council following years of campaigning. They also commissioned film-maker Derek Smith to interview the survivors of the disaster for a documentary that formed part of an exhibition.
The town council were unable to erect the brass plaque on the bridge itself due to objections from the local landowner, who feared it would become a 'shrine'.
Coun Steve Walmsley, who has led the campaign, said: "A lot of people have been involved in this and it will be part of the wider restoration of the town hall. We've traced the three teenagers from Hull who were camping near the scene and tried to get help, and the artist Lincoln Seligman, who was staying in the cottage and helped the survivors. Some of the first responders (from the emergency services) are coming too.
"We still travel up and lay flowers near the scene. The locals call Dibbles the 'devil's bridge' and there are still accidents there. We think the road should be realigned.
"Thornaby is a close-knit place and I remember the accident was only about a week before I got married. I went out that night and in the local club everybody was talking about the crash - they were really shocked. This memorial has been a long time coming and it recognises the immensity of the tragedy. There's been a lot of goodwill from people - the stonemason who made the recess for it didn't even charge us when they found out what it was for."
The last two survivors of the accident only died within the past year.
"So many families lost mothers, grandmothers and aunties. They went on this lovely day out and they never came back. They were pensioners, but some of them were only in their early 60s, which by today's standards doesn't seem that old. It was a scene of carnage and bloodshed."
Dibbles Bridge - a history of accidents
In April 2020, American engineer Craig Barnhart died at Dibbles Bridge when the brakes on his e-bike failed as he cycled with his wife.
In 2015, cardiologist Dr George Ballard fell 50ft into the River Dibb after colliding with the bridge and died. He was thrown over his handlebars in the collision while cycling with his friend Dr Nick Hayward, whom he had overtaken before the descent to Dibbles Bridge. The 41-year-old from Ben Rhydding, near Ilkley, worked at Leeds General Infirmary and had a wife and two children.
In 2014 Skipton cyclist James Nelson was also killed in similar circumstances at the same spot. The 32-year-old was on a training ride with Skipton Cycling Club when his brakes locked on the descent and he fell into the river bed below. His body was not found until the next morning by Environment Agency workers surveying the river.
Safety barriers have since been erected.
Interested in all things Yorkshire heritage? We’ve just launched a free newsletter to bring you the latest stories straight to your inbox. You can sign up here: https://www.yorkshirepost.co.uk/newsletter