Boating enthusiast Luke Fitzherbert, 69, was killed instantly when he and his wife Katrin were struck by a Subaru Impreza on the A5 just south of Weedon, close to where they had moored their narrowboat.
Road collisions have now claimed the lives of five people on the same stretch of the A5 in the past 12 months.
An inquest in Northampton today heard the car was being driven "in the region of" the road's 60mph speed limit by 59-year-old Bertram Iles who told the hearing he did not see the couple before hitting them.
Mrs Fitzherbert, who had a leg amputated as a result of the injuries shesuffered in the crash outside The Narrow Boat Inn in January, described the couple's desperate efforts to avoid being hit by the approaching car.
She said: "I saw a set of car headlights off to my left but they were very far away so we didn't hesitate to cross.
"As we were crossing I heard a noise of an accelerating car and sensed there was something very dangerous happening.
"I started to run and as I was running I also heard Luke shout out 'run'. I hoped to God he was running too."
Mr Fitzherbert, who was from Totnes in Devon, was thrown against a bridge in the impact and a post-mortem examination revealed he died instantly of severe multiple injuries.
Mr Iles of Pattishall, near Towcester, said he barely had time to react before the collision and described the aftermath as being "like a nightmare."
He said: "This was a tragic accident. I did everything I could to avoid it and I'm devastated that the gentleman died and the lady sustained serious injuries."
Coroner Anne Pember recorded a narrative verdict.