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[Jones]

From the "Accident" thread in the History and nostalgia forum :

12th March 2001

Nine passengers were injured when two trains collided outside a London station during rush-hour.

The two Connex South East Networker trains clipped each other outside Hither Green station near Lewisham in south east London.



My question is this, how is the "six foot" guaranteed?

Sometimes that far rail gets very close to the bottom of the window when I look at the track. Would it be possible for two trains to clip each other in a random accident?

 

[PG]

I guess anything would be possible in a random accident...

Seriously though one or other of the trains would have to be out of guage in order for two trains to clip each other in normal circumstances.

In the incident you refer to I believe one of the trains had passed a signal at danger hence the collision.

 

[carriageline]

Also, the six foot isn't actually always six foot, it's a name more than a measurement, AFAIUI

 

[edwin_m]

There is periodic maintenance where the track is restored to line, which will put the six foot back to whatever its design value is. In practice the six-foot would have to narrow a lot before the trains are at risk of touching, and this would be obvious either by visual inspection of the track or on the geometry recordings made by the inspection trains.

There is also a method of directly measuring the six-foot by lasers, which I believe was used when the WCML was upgraded for Pendolinos, as these needed a bit more clearance when tilting.

 

[swt_passenger]

I guess anything would be possible in a random accident...

Seriously though one or other of the trains would have to be out of guage in order for two trains to clip each other in normal circumstances.

In the incident you refer to I believe one of the trains had passed a signal at danger hence the collision.

That's definitely how it was reported at the time. There is no RAIB (or predecessor) inquiry report available, so they must have thought there was nothing to investigate. I don't think the OP needs to worry about trains touching because of the 6ft reducing, Hither Green isn't a precedent for that.

 

[455driver]

The 6ft can be very tight in places, at Waterloo the gap between the up slow(routed into 4) and the down fast (routed into 5) is very tight especially if the 455 driver makes sure the front of his train is lined up with the middle of the 444 coach .
I would say its no more than 3 or 4 inches between them, this is also the reason 444s are banned from the up slow from W14 signal into platforms 1-4 at Waterloo itself.

Also the slow lines at Clapham Jn (main) are very tight, you cant get a sheet of A4 between the front corner of the down train and the middle of the up train, I have tried!

 

[Ploughman]

The terms Sixfoot, Fourfoot and Tenfoot are all generic terms and are not measurements.

However old style relaying often made use of the Six Foot Gauge a steel bar with a rounded stop at each end.

6 ft intervals are still in the main approx 6 ft but more for convenience than anything else.

There are numerous places on the network, that due to historic reasons such as minimum land take on construction, we are left with very tight clearances.
The Newcastle - Sunderland line between Seaburn and Monkwearmouth used to have a 6ft that you could run trains on 1435mm. I do not know if it still does.
The ECML South of York at Dringhouses.
The 6ft is wider than the 10ft. This created problems on a renewal as a pair of tracks had to be kept open for the Airport services. In the end the renewal was dated for a total shut down over a christmas period so we could use the Ballast cleaner and tracklayers safely.