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History of failures


NATM was originally developed for tunnelling in soft, less predictable rock strata. It is an open face method with stability provided by rock bolting and shotcreting.

There have been a number of high profile failures over the last 20 years, the most notable in the UK being the Heathrow Express tunnel collapse of October 1994.

A month before, another NATM collapse in Munich swallowed a bus, killing four people.

In 1999 the Health & Safety Executive estimated that there had been at least 39 cases of collapse or serious deformation on NATM projects between 1973 and 1979.

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