A tragic crash near Mildenhall would not have occured if more speed limit signs had been in place, Suffolk's senior coroner has said.
In a report to prevent future deaths sent to Suffolk Highways and Kier Highways Ltd, Nigel Parsley set out his concerns following an investigation and inquest into the death of Stephen Coombes.
The 67-year-old from Banbury, Oxfordshire, died in Addenbrookes Hospital, in Cambridge, five days after being involved in a single vehicle collision on the A1101 at Burnt Fen, near Mildenhall, last year.
Police investigation following the fatal crash identified a deep depression in the road surface which contribute to Mr Coombe's losing control of the vehicle.
The report said: "This depression was known to be present by the Highways authority, and a temporary 30 mph speed limit (instead of the usual 50mph) had been put in place.
"Inadequate road signage did not reflect the temporary 30mph limit and John hit the depression at approximately 50mph, his vehicle being forced off the road as a result. Had John known to negotiate the depression at 30 mph, this tragic incident would not have occurred."
A forensic crash investigator gave evidence at the inquest reporting test results carried out in a police vehicle over the depression in the road at various speeds.
These tests found at 30mph the vehicle was able to navigate the depression with "relative ease" and reacted "significantly" when travelling at 50mph.
The report said: "At the time of Johns's collision, he had just overtaken another vehicle and therefore crossed the depression a slight angle as he returned to his own side of the carriageway.
"When the police officers replicated this vehicle movement at 50mph, the police vehicle reacted violently, with one of the rear wheels leaving the surface of the road. The officer driving that vehicle was not prepared to attempt the same manoeuvre at any higher speed due to the risk involved."
The report said there was only one 30mph temporary sign in place and "left road users and attending police officers unaware of the reduced speed limit in place".
A spokesman for Suffolk Highways, said: “We have supported Suffolk Police with their investigation surrounding the tragic fatality on the A1101 Burnt Fen on 29 August 2021.
“Recent works have been completed to remove some of the undulating road surface which can occur on fen roads. Whilst a longer-term solution is implemented, we’ll continue to monitor the location and maintain a temporary speed limit of 30mph to reduce vehicle speeds.”
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