When the lights changed on Michigan Avenue in downtown Paw Paw shortly after three o'clock yesterday afternoon, the traffic started moving immediately.

The driver of a white articulated lorry heading for the Ralph Moyle Trucking Company five miles out of town did not see Ben Carpenter struggling to cross the road in his motorised wheelchair, and he did not detect the moment when Mr Carpenter's wheelchair handles stuck fast in the grille of his truck.

On the street, the sound, Mr Carpenter told a local television station, was "kind of like train cars coming together, something like that".

So the driver accelerated smoothly, ignoring the screams of pedestrians and waving arms of other motorists and headed for the Red Arrow Highway with his unknown passenger. Mr Carpenter, who suffers from muscular dystrophy and was strapped firmly in his chair, watched and smelled the rubber wheels of his wheelchair burning up in the wind as the speed rose to 50mph.

"I was probably thinking that this is going to keep going and not stop anywhere, 50 or 60 miles somewhere," he later told WOOD-TV of Grand Rapids, Michigan. "What if I end up in South Haven? I mean, I would have been dead way before that."

As the white truck, known as a "semi" or big rig in America, rolled west out of Paw Paw, a small town 140 miles (225 kilometers) west of Detroit, the local emergency services started receiving calls, which were later posted on the internet.

"I'm sitting at the corner of Michigan and Hazen Street, in Paw Paw," reported one caller. "A semi truck just came by. He does not know it but he's got a gentleman on the front of his truck that is in a wheelchair and he is pushing him down the road and there is a girl on a bike screaming after him and waving and trying to get the truck to stop."

"He's westbound," said another. "He doesn't know he's dragging this man."

Mr Carpenter, meanwhile, thought nobody had noticed his misfortune. "It was fast, I know that. Faster than this chair was made to go," he said. "I was thinking, the cars keep going by and nobody bothered to stop."

Dispelling thoughts that the emergency calls were a prank, state troopers set out to follow the lorry and Mr Carpenter's drive ended when the police and the rig pulled into the Ralph Moyle depot. The driver did not believe what had happened until he saw Mr Carpenter, who was wearing a red t-shirt, mounted on his grille.

"I was happy. Thank God it was over," Mr Carpenter said. "I thought it was kind of like a fair ride. I don't remember feeling any bumps though. I must have, but the road must have been pretty smooth."

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