Not so amusing incident

And I was on duty at the time it happened as Head Controller. It was 1962 Stock DM 1531 that was damaged.

Its place was taken by spare DM 1659, suitably renumbered 1531 in Jan-87. (1659 became spare after the Holborn collision of 9/7/80, being the only undamaged car of that 4-car unit).

The original 1531 was eventually repaired, converted from 'D' to 'A' and replaced 1416. 1531 was then renumbered 1416 in Jan-90.

The incident train was set 13 (!) working the 10.28 Ealing - Hainault via Newbury Park. The 'obstruction' in the tunnel roof was reported at the time as being a 200 mm diameter drill which penetrated the roof of the tunnel close to Whipps Cross roundabout where test borings were taking place for the M11 link road.

From the June 1986 issue of Underground News -

The drill bit was broken on impact, causing extensive damage to the driver's side leading motor car 1531. Fortunately, the driver suffered only minor injuries, having ducked when realising what was happening. He then drove the train into Wanstead station from the rear with the guard at the front, and a chain of passengers relaying messages along the train because the accident had rendered the driver-guard train telephone inoperative. Train 15, the 10.52 ex-Ealing weas emptied of its passengers and sent forward to investigate (no train radio then!), at which time the nature of the problem had not been established ..... The contractor performing the drilling, realising the loss of the bit, had then put down an investigating probe, which was hit by train 15. This train was not so badly damaged as it was travelling at caution speed and much slower than train 13 had.

Many thanks for the quick and very informative replies on this one.

In cities where there are giant tunnel networks, you would expect people to first see if there's anything underneath them? Common sense. Always been rare...

Clearly didn't check enough. There's a well known phrase in the building trade - measure twice, cut (or drill) once.

I'd lay money on the fact that, if I used a large drill on the Euston Road, I'm more than likely going to end up breaching the Met Line tunnels. Our lines have been there years, and don't generally move around.

Guaranteed whenever any large holes start to get dug round my way, I somehow know that within a couple of hours something will happen to my electric or water supply ;D

NTL / Virgin etc. have a well-known reputation for this - as a Transco engineer once showed me (whilst searching for a suspected gas leak). When laying most of the cable network, they obtained (on the cheap) the many of the street diagrams needed, mostly from the utility companies. This saved them thousands of pounds in planning etc.

Many miles of cable are laid just above gas mains which were already in situ. So now, everytime the gas main is dug up, you can bet they end up cutting NTL cables - and have to reimburse NTL/Virgin for the damage of course. The very company that saved money / cut corners thanks to them.