A school bus driver told how he saved 11 children by reversing off Eastham Bridge in Tenbury Wells as its apex went crashing into the River Teme.
Worcestershire County Council has launched an investigation.
The authority's councillor responsible for highways said lorry drivers "chose to ignore the advice".
Lorries had been in the area for road works, the council said.
Marcus Hart, cabinet member for highways, said: "Plainly there was suitable signage in terms of unsuitable for heavy goods vehicles and obviously lorry drivers chose to ignore advice."
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Barry Gutteridge, who lives nearby, said: "We get lorries weighing 25 tonnes. No wonder the bridge collapsed."
Mr Gutteridge from Eastham said he had seen 17 loads of stones go over the bridge on Tuesday - the day it gave way.
Bus driver Derek Trow was taking pupils home from Lindridge St Lawrence CE Primary School in Tenbury Wells when the bridge collapsed.
He saw the road give way ahead of him and managed to back up moments before it crumbled.
"There was an almighty row and the apex collapsed leaving a drop of about 10ft," the 62-year-old said.
"We would have gone down there. We were lucky."
The Grade II listed structure was built in 1793 and was originally a toll road until the council made it free in 1907.
The council said the bridge was routinely inspected last December but because it is listed, repairs will take at least a year to carry out.
The area has been made safe and an investigation had been launched, a spokesman said.
He added: "Our investigations into the cause of the collapse are continuing and until we complete that process it would be wrong for us to speculate."
A 10-mile diversion along the A443 remains in place.
Lorries carrying tonnes of stones ignored weight limit signs near an 18th century bridge before its spectacular collapse, it has been claimed.