Whilst I don't wish to speculate, but truck brakes are designed to be failsafe. In the event of the service brakes failing then the parking brake should be able to bring the vehicle to a halt. A vehicle of that size would also be equipped with an exhaust brake which also provides some braking assistance. It's been a while since I've driven a Scania, but the engine braking on Volvo trucks is extremely effective, used correctly a steep hill can be descended with virtually no use of the service brakes required.
As I understand it the driver was sounding his horn to warn people to get out of his way, so it now remains to be seen why the situation arose whereby the vehicle got out of control, and the parking brake wasn't or couldn't be used, or indeed if it was used and wasn't able to stop the vehicle then why not!
...Philip Browne, 65, a semi-retired driver who has lived on Lansdown Lane for 40 years, was one of the first on the scene.
He said: "I was in the driveway washing my car and I heard a big bang. It sounded like a big, hollow bucket had been dropped.
"I ran down to the bottom of the drive and saw the lorry lying on its side.
"Just as I got there the driver of the lorry was climbing out through the broken windscreen.
"The poor chap was in bits. He was looking for a coat and was shaking and upset. He was in a state of shock.
"He said 'I think I've killed somebody'. He said that he was coming down the hill and his boss was driving in front of him.
"His boss stopped at the crossing. He said that he tried to apply the brakes but they didn't work and then he grabbed the handbrake.
"He was sounding his horn, trying to get people out if his way. He said he was trying to slow down by driving along the houses' walls."
Mr Browne, who has a five-year-old grandson at nearby Weston All Saints Primary School, stayed with the driver before he was taken to hospital by paramedics.
He added: "I've lived here for 40 years and it is a very dangerous road. Do I fear for my grandchild going to and from school? Yes I do."
The lorry is understood to have been 8ft wide but would have been allowed to use the road if it was travelling to a site only accessible via Lansdown Lane. A sign advertising the restriction at the junction at the top of Lansdown Lane has been knocked down.
A spokesperson for Bath & North East Somerset Council said traffic calming measures had been introduced to the road five months ago.
They added that the lorry was not connected to a construction project at the school, or any other council projects in the area...
One sign of two in place.
There is a grisly history to runaway lorries off Lansdown Road - weight limit since applied... No runaways since.
Bath Fire Brigade and Ambulance Service, 1891 to 1974: An Illustrated History. http://tinyurl.com/n27mwn9
See PP. 164 : 171
24th July '64 Loaded ready mix truck Lansdown Road - 2 killed.
3rd April '70 Truck loaded with drainage pipes Lans' Road - 2 killed.
Weight limit imposed - no headline tragedies since.
Lansdown Lane a side road off Lans' Road - 20 mph limit, road narrowed, width restriction Access excepted ... Now we have 4 dead following one truck runaway.