GN Class 717

[bramling]

If a 700 works on third rail without doing 30mph, it's fair to say a 717 can do its max speed too. The Moorgate tunnel is a special case and it's not exactly a long way from Drayton Park to Moorgate anyway. Besides Essex Road to Old Street, the stations are pretty close together so how fast could a train get to before slowing down again?

The 313s came very soon after the Moorgate accident, which was almost certainly the reason for the restriction. If I remember righty the 313s are not limited to 30mph as such, simply the motors cut out at that speed, although it was felt that trains would be unlikely to gain much more speed due to air resistance in the tight-fitting tunnel.

It presumably adds a further layer of assurance to the signal overlaps - which could also apply to those for the stop signals elsewhere in the tunnels? Perhaps a signalling expert may be able to elaborate on this.

 

[BelleIsle]

It's not the third rail bit but surely the tripcock signalling bit?

The tripcocks were removed when the line transferred to BR. The lightweight bogies used by some modern units do not even have the space to fit the equipment. I am told that ones of the reasons the Desiro City uses a mixture of disc and tread brakes is for this reason.

 

[A0wen]

The tripcocks were removed when the line transferred to BR. The lightweight bogies used by some modern units do not even have the space to fit the equipment. I am told that ones of the reasons the Desiro City uses a mixture of disc and tread brakes is for this reason.

Not sure that's correct - I think tripcocks do exist on the NCL still, so does this article:

https://en.wikipedia.org/wiki/Northern_City_Line
"
Passing signals at danger[edit]
If a train is standing at a signal at danger inside a tunnel and the driver is unable to contact the signaller, the driver is permitted to pass that signal under their own authority. As soon as the train starts to move, the tripcock on the train will operate and stop the train so the driver must reset that before continuing."

I'm sure I read somewhere that one of the early issues with the 313s was the BR designed tripcock mechanism was being damaged by the ex Underground line-side tripcock equipment so the BR equipment had to be upgraded.

 

[transmanche]

The tripcocks were removed when the line transferred to BR.

Er, no they weren't. The 313s have tripcocks. You can actually see the train stop in the photo of Drayton Park below. And a tripcock detector was installed at Finsbury Park. If the tripcock detector can't prove the presence of a tripcock, the service is diverted to King's Cross.


NCL Procedures Sign 01 [CC BY-SA 4.0], by Ivor the driver, from Wikimedia Commons

 

[jon0844]

Apparently when the new signals go in, which will have to be further back to allow the 717s to stop at the end of the platform (or have the rear door locked out as it won't be in the station) the system will use ordinary signalling and the tripcock system will be retired.

This may just be a rumour, although moving the signals is very much an issue.

 

[bramling]

Apparently when the new signals go in, which will have to be further back to allow the 717s to stop at the end of the platform (or have the rear door locked out as it won't be in the station) the system will use ordinary signalling and the tripcock system will be retired.

This may just be a rumour, although moving the signals is very much an issue.

Presumably the functionality of the trainstops would be achieved by TPWS, which wasn't around in the 1970s.

 

[jellybaby]

Are the 717s fitted with tripcocks or is the signalling into Moorgate going to be upgraded to something else (TPWS?) first and have both running together for a while?

 

[XCTurbostar]

Are the 717s fitted with tripcocks or is the signalling into Moorgate going to be upgraded to something else (TPWS?) first and have both running together for a while?

As this article suggests, I don’t know how they could do anything but fit them. http://www.railtechnologymagazine.com/Rail-Industry-Focus-/the-almost-forgotten-cascade

Because the 717s are replacing 313s we can’t do anything to the signalling while the two are operating, particularly between Drayton Park and Moorgate.

 

[transmanche]

Presumably the functionality of the trainstops would be achieved by TPWS, which wasn't around in the 1970s.

Train stops and TPWS/AWS co-exist at places already (e.g. Richmond and Wimbledon branches of the District line).

AFAIAA, the 313s are fitted with TPWS, so the Northern City line could have been upgraded at any time over the past couple of decades - but hasn't been.

 

[hedpe]

The 717's are fitted with Tripcocks for the NCL. The tripcock is positioned infront of the first wheel axle, whereas on 313's it's just after. Unlike 313's, it's totally electronic and the onboard computer initiates the brake demand.

GN 313's have a speed limiting switch controlled by the WSP which automatically cuts motoring if speed exceeds 30mph when taking power from third rail.

 

[urpert]

That whole Wikipedia article is fascinating. I had no idea the operating procedures were so different.

 

[petersi]

That whole Wikipedia article is fascinating. I had no idea the operating procedures were so different.

You may find this old video of the safety procedure interesting

 

[BowesRanger]

Saw one of these running North through Bowes Park station today, around 11am I think. Assume not in service, but good to see nonetheless

 

[APUK002]

Saw one of these running North through Bowes Park station today, around 11am I think. Assume not in service, but good to see nonetheless

Oo,kl

 

[jon0844]

Saw two more 717s being delivered somewhere today.. passing through WGC northbound in the morning.

 

[332 > 444]

009 was moving under it's own power in Hornsey around 14:45.

 

[APUK002]

Saw two more 717s being delivered somewhere today.. passing through WGC northbound in the morning.

Ya,on fb.

 

[Class315]

Saw two more 717s being delivered somewhere today.. passing through WGC northbound in the morning.

For the record, the two most recent deliveries where 717009 & 717005. This delivery route is not unfamiliar to New Siemens trains being delivered as they come via Camden Road Incline up to Peterborough and reverse back towards to London Via Hertford.

No 717 has left the depot under its own power yet, only manouvering around the depot. the train passing through Bowes Park at 11:20 was 3E53 Hornsey Depot - Letchworth.

 

[Class315]

Mainline testing of the 717’s commenced overnight with 007 doing the honours of being the first new unit to operate down the Northern City Line.

It operated as http://www.realtimetrains.co.uk/train/K02733/2018/07/24/advanced

 

[jon0844]

Testing this morning too. Didn't go so well apparently.

 

[Class315]

Testing this morning too. Didn't go so well apparently.

Now, Jon did you expect any different? When incidents are pretty much a weekly occurrence down there! Action needs to be undertaken!

 

[BowesRanger]

Testing this morning too. Didn't go so well apparently.

How so? I'm desperate for these to come online as soon a humanly possible

 

[03_179]

Testing this morning too. Didn't go so well apparently.

What happened as I haven't seen anything on it.

 

[jon0844]

A fire (trackside, presumably caused by shoegear).

 

[03_179]

thanks

 

[sprunt]

How bad is that? Is it a typical teething issue, or something serious?

 

[Fred26]

Ignore.

 

[332 > 444]

How bad is that? Is it a typical teething issue, or something serious?

Probably part of the NCL catching fire again.

 

[BlyRF]

Probably part of the NCL catching fire again.

I don’t think one fire is gonna bring a grand holt to introductions and overall testing.

Anyway have there been anymore deliveries to the deport yet?

 

[jon0844]

I don’t think one fire is gonna bring a grand holt to introductions and overall testing.

Anyway have there been anymore deliveries to the deport yet?

It was dealt with quickly and the train left under its own steam (!).

There are actually quite a few reports of fire/smoke at Moorgate, and sometimes I wonder if it's down to a spark from the third rail lighting rubbish, or someone thinking they saw smoke which was actually someone vaping at the end of the platform. Many reports of smoke turn out to be false alarms, which gives credence to my theory.