Airport idea

[phil-b259]

On 17/12/2019 at 01:27, The Johnster said:

Gatwick Airport; I knew it would come up sooner or later...  

 

If the cable cuts the power this is to reduce the danger of sparking setting fire to the crashed a/c rather than stopping trains that are too close to be stopped.  Most traffic stops at the station anyway and is not travelling at high speed.  It cuts traction power to electric trains of course but has no such effect on diesels, and of course there was still a lot of steam traffic when the airport opened.  I imagine it puts the signals to danger as well,

 

It most certainly does put the signals back in the vicinity of the runway. Under the older interlocking it also used to set routes and try to clear signals heading away from the runway area  to try and avoid trains stopping where planes might crash (This feature got 'missed' from the new SmartLoc computer based interlocking when the area was resignalled during the platform 7 build).

 

If the tripwire breaks the 3rd Rail is turned off between Balcombe Junction, Crawley and North of Horley (all lines), Although seemingly excessive the problem is the need to consider trains which may straddle the boundary between two substations - and liven up conductor rails that should be dead by the units pick up shoes.

 

Electrical control have the ability to reconfigure the circuit breakers to ignore the trip wire if required - though for obvious reasons this is very much the exception rather than the rule. They can also obviously restore power with the tripwire still broken once they have received assurances that there is no aircraft incident taking place.

 

The tripwire is also linked to a button on the signalling control panel covering Gatwick allowing the signaller to perform the same function (signals to red, traction power off) if they are advised of an aircraft emergency from Gatwick Control Tower.

 

As with the traction supply, should the tripwire be broken (or the aircraft emergency be resolved) then the signaller can restore the signalling to normal operation from their panel (Restoration of the traction supply requires Electrical Controls involvement however).

 

The tripwire functionality should be tested every 84 days by the S&, however...

 

(i) Given the large traction isolation area it causes,

(ii) The inability to do it if a T3 possession falls within the isolation area (danger of accidental recharging of the conductor rail within said possession when restoring power after the test)

(ii) Trains run frequently throughout the night as far as Three Bridges - the only gap you get is around 03:00 for 20 minutes

(iv) The fact that we also have other faults / maintenance / corrective works that can only be done at night / p-way job cover

 

... It rarely gets done on time.

 

 

Edited December 31, 2019 by phil-b259