Sections of pipe taken from the ground in Rawcliffe Lane, York, are undergoing forensic tests to try to find the cause of last week's Clifton gas leak.

FLASHBACK: Flames lick against a house close to the gas leak in Rawcliffe Lane, Clifton, York

The Health and Safety Executive has removed the pipe and sent it to the specialist pipeline section in Nottingham where it is being examined as part of an ongoing investigation.

The leak sparked a massive fireball which ripped up the road and sent flames leaping 40ft into the air.

Miraculously there were no casualties despite 300 residents being evacuated. The gas supply to more than 1,500 Clifton properties was cut off until the following Monday.

One of the theories under investigation is that the extra weight of traffic stopping in front of a new pedestrian crossing near the leak could have put pressure on the 12-year-old joint in the medium-pressure main.

In a letter to the Evening Press, Rawcliffe resident Richard Lamb, of Greystoke Road, said: "The position of the excavation and road resurfacing is just in front of a fairly recent new pedestrian crossing.

"Maybe the effect of the traffic waiting for pedestrians to cross with the resulting standing weight and possible vibrations caused the pipe to fail."

A spokeswoman for the Health and Safety Executive said: "This is indeed one of several theories being considered."

Meanwhile, Transco has dug another ditch in the opposite side of the road to check that a low-pressure main is in good condition.

John O'Grady, spokesman for the company, said: "We had some minor works in Rawcliffe Lane to make sure that the pipe on the other side of the road was OK and everything was fine.

"We have also written letters of apology this week to residents in the area who were either evacuated or had their gas supplies turned off."

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