GN Class 717

Status
Not open for further replies.

Bald Rick

Veteran Member
Joined
28 Sep 2010
Messages
12,672
It’s not cab signalling which enhances frequency, it’s CBTC. And cab signalling comes with that.
Need to be careful with terminology. CBTC is a term usually associated with certain types of signalling used on the underground, and Crossrail of course.

Shorter block sections allow shorter technical headways and therefore improved planning headways and thus higher frequency, up to a point, limited by braking distance between signals and linespeed.

ETCS (or similar) cab / radio based signalling systems enable a further reduction in block sections, not limited by braking distance and linespeed, and this does enable a small improvement in technical and planning headway and therefore frequency, but usually only at lower speeds and plain track.

ATO removes any variability in driver behaviour, and also enables a ‘braver’ driving style, ie braking later than a driver would for a station. In effect this allows a reduction in the ‘margin’ between technical headway and planning headway, which further improves frequency.
 
Sponsor Post - registered members do not see these adverts; click here to register, or click here to log in
R

RailUK Forums

TRAX

Member
Joined
2 Dec 2015
Messages
1,108
Location
Paris, EU
CBTC is precisely the term used to describe moving block signalling, where trains communicate their positions, speeds, etc. all the time and where data is transmitted wirelessly between ground and trains.
 

choochoochoo

Member
Joined
6 Aug 2013
Messages
668
Yes you can. That is precisely how Thameslink ETCS / ATO works. There’s nearly twice as many blocks with ETCS in the core than with conventional signals, and both can (and do) operate at the same time on the same line with consecutive trains.

Thanks. So can a train using in-cab signalling can follow a train using conventional TCB into the core? How does the ETCS-using train know where the train using TCB is ahead of it if that ETCS section has more blocks than conventional TCB. Do the two systems talk to each other ? Or does the ETCS train then obey conventional signals ?
 

Bald Rick

Veteran Member
Joined
28 Sep 2010
Messages
12,672
Thanks. So can a train using in-cab signalling can follow a train using conventional TCB into the core? How does the ETCS-using train know where the train using TCB is ahead of it if that ETCS section has more blocks than conventional TCB. Do the two systems talk to each other ? Or does the ETCS train then obey conventional signals ?
Yes trains using different systems can follow each other - and they do.

The crucial thing is that both systems use the same interlocking and train detection. The different ‘system’ is merely the manner of communicating messages from the interlocking to the train and driver. Trains using either system do not need to know (and don’t) where the ‘next train ahead’ is, all the train / driver is advised is how far they are allowed to proceed, ie the ‘movement authority’. Under the conventional signalling, this message is conveyed to the driver by the signals, and the driver drives accordingly. Under ETCS / ATO the message is conveyed to the train by radio, and converted into a speed profile, with the location of the ‘0mph’ being the limit of movement authority. Then either the driver or the ATO drives to that speed profile, disregarding the signal aspects.

The main difference is that under conventional signalling there must be one complete signal section block (which will be several train detection sections) plus overlap, free ahead of a train before a proceed aspect can be obtained on the signal. For ETCS it only needs to be sufficient train detection sections, plus overlap, to allow for train braking distance at the speed the train will be permitted to travel at.
 

Fred26

Member
Joined
5 Mar 2010
Messages
1,017
You get some with shorter blocks, and some more with ATO. The former runs trains closer together, the latter allows more aggressive (and consistent) braking for stations and speed restrictions; the latter is a particular issue at Moorgate.

IIRC the NCL had 18tph in the peak when the 313s first arrived in the late 70s.
Do you know how 18tph was achieved?
As a layman looking at OpenTrainTimes, it seems there are 18 sections on the NCL. Are these the same sections that were in place when 18tph was active? Would it be possible to increase from the current maximum of 12tph without signalling changes - say 14tph?
 

Bald Rick

Veteran Member
Joined
28 Sep 2010
Messages
12,672
Do you know how 18tph was achieved?
As a layman looking at OpenTrainTimes, it seems there are 18 sections on the NCL. Are these the same sections that were in place when 18tph was active? Would it be possible to increase from the current maximum of 12tph without signalling changes - say 14tph?
AIUI, there were more signal sections.

The issue with going to 14tph (which was the franchise plan a long time ago) is that it is not compliant with current train planning rules, which require extra time for the traction changeover at Drayton Park.
 

Mcq

Member
Joined
24 May 2019
Messages
109
The time now is 12:46 and yet the 13:25 due to leave Moorgate is cancelled because of 'failure of the electricity supply' - nothing else seems to be affected
Can anyone explain?
 

Bald Rick

Veteran Member
Joined
28 Sep 2010
Messages
12,672
The time now is 12:46 and yet the 13:25 due to leave Moorgate is cancelled because of 'failure of the electricity supply' - nothing else seems to be affected
Can anyone explain?
Inbound service presumably cancelled due to an earlier power failure. If the inbound can’t run, then neither can the outbound!
 

codek

Member
Joined
11 Oct 2018
Messages
14
Are the latest reliability figures out yet?

The last 2 weeks seem to have been pretty bad. Siemens must be pretty embarrassed?

Have they really not exceeded the reliability of the 313s yet?
 

samuelmorris

Established Member
Joined
18 Jul 2013
Messages
4,587
Location
Brentwood, Essex
Are the latest reliability figures out yet?

The last 2 weeks seem to have been pretty bad. Siemens must be pretty embarrassed?

Have they really not exceeded the reliability of the 313s yet?
As far as I'm aware 717 reliability figures are not released to the press. Not sure why they're excluded but they received one token entry in MRM a few months back and have been conspicuously absent ever since. It's not even as if they were anywhere near the bottom of the league. On a per-train basis they are probably drawing close to 313 reliability now, but not on a per-unit basis yet.
 

choochoochoo

Member
Joined
6 Aug 2013
Messages
668
Are the latest reliability figures out yet?

The last 2 weeks seem to have been pretty bad. Siemens must be pretty embarrassed?

Have they really not exceeded the reliability of the 313s yet?
In my opinion, I don't think they were tested enough before entering service. Lots of little niggles still exist. Most of these should've been discovered if adequate testing had been carried out. It looks like there was a rush to get them signed off as ok for service.
 

codek

Member
Joined
11 Oct 2018
Messages
14
As far as I'm aware 717 reliability figures are not released to the press. Not sure why they're excluded but they received one token entry in MRM a few months back and have been conspicuously absent ever since. It's not even as if they were anywhere near the bottom of the league. On a per-train basis they are probably drawing close to 313 reliability now, but not on a per-unit basis yet.
Interesting.

Now we're 100% 717 though, we could use the general reliability figures i guess. Will wait a few months and see what they look like!
 

Failed Unit

Established Member
Joined
26 Jan 2009
Messages
7,493
Location
Central Belt
Interesting.

Now we're 100% 717 though, we could use the general reliability figures i guess. Will wait a few months and see what they look like!
This month in Modern Railways the class 313 made an appearance in 3rd place. It was higher then the class 700 (which will upset a lot of people on this forum who seemed to imply the 313s were as bad as the 230s) I doubt that the 717s are doing better than the 313s. The whole point of them appearing in the table was showing that unmaintained train was doing better than the majority of new trains.

From a use point of view, although the 717s break down a lot, the service is about the same as it ever was. Failed trains are on the up, but trains cancelled due to staff shortages on the way down. So everything balances out. Agree I doubt Siemen's will be full of pride. The other thing is the turn out of trains is much better since the 717s appeared. I doubt that the graffiti artists don't want to attack the 717s so it does add more value to the argument that GTR were delibrately not cleaning graffiti off the 313s to make them look bad (so people would be glad of the 717s)

Still not seeing the improvement in the service yet comfort wise (if you compare a 717 to a well maintained 313) but the leaf fall season is much better (when the trains don't break down)
 

St. Paddy

Member
Joined
11 Sep 2019
Messages
116
Location
Hitchin
This month in Modern Railways the class 313 made an appearance in 3rd place. It was higher then the class 700 (which will upset a lot of people on this forum who seemed to imply the 313s were as bad as the 230s) I doubt that the 717s are doing better than the 313s. The whole point of them appearing in the table was showing that unmaintained train was doing better than the majority of new trains.

From a use point of view, although the 717s break down a lot, the service is about the same as it ever was. Failed trains are on the up, but trains cancelled due to staff shortages on the way down. So everything balances out. Agree I doubt Siemen's will be full of pride. The other thing is the turn out of trains is much better since the 717s appeared. I doubt that the graffiti artists don't want to attack the 717s so it does add more value to the argument that GTR were delibrately not cleaning graffiti off the 313s to make them look bad (so people would be glad of the 717s)

Still not seeing the improvement in the service yet comfort wise (if you compare a 717 to a well maintained 313) but the leaf fall season is much better (when the trains don't break down)
Security guards patrolling sidings has improved the graffiti situation. If they do get tagged, the paint is of high quality and the graffiti cleans off very well, unlike the vinyl on the 313s
 

Mikey C

Established Member
Joined
11 Feb 2013
Messages
3,421
Security guards patrolling sidings has improved the graffiti situation. If they do get tagged, the paint is of high quality and the graffiti cleans off very well, unlike the vinyl on the 313s
Now there's a shocker, having security patrols reduces graffiti and vandalism...
 

ainsworth74

Forum Staff
Staff Member
Global Moderator
Joined
16 Nov 2009
Messages
22,023
Location
Redcar
I've finally managed to use some of these today and apart from the Irish fella trying to preach the word of God on one train and the pair of beggars on the second I was very impressed! Okay seats are rock hard but were acceptable but otherwise so much better than the grotty 313s they replaced.

However I'm wondering what regulars make of them and in particular those using them in the weekday peaks? Have they improved conditions at all I wonder?
 

ainsworth74

Forum Staff
Staff Member
Global Moderator
Joined
16 Nov 2009
Messages
22,023
Location
Redcar
I’m an occasional, rather than regular, peak user, but they have improved matters significantly.
Looking at them I'm guessing it's the hoovering up capability along with a design that lends itself to standing that's making a big difference. I also figure there's actually a good chunk of extra capacity considering there's no extra intermediate cabs and you don't have the staff only space behind the leading and trailing cabs lost to passengers?

Impressive bits of kit!
 

jellybaby

Member
Joined
27 Dec 2012
Messages
329
However I'm wondering what regulars make of them and in particular those using them in the weekday peaks?
The stopping point at my local station is still a bit variable which means I can't wait where the doors will be for better racing pregnant elderly passengers with broken legs carrying babies to the remaining seats.

Finsbury Park feels less of a shuffle when lots of people change due to more space to move about inside. On the other hand the person in the aisle seat needs to get up to let the window seat person out while in the old facing seats you could just swing your legs round a bit.

The seats are a little flimsy and it is annoying when people jam their knees into the back of yours and hence your back.

The temperatures are generally better, less drafty in the winter.

The doors that close on a timer before the train is ready to depart can be annoying if you are running for a train.

I also figure there's actually a good chunk of extra capacity considering there's no extra intermediate cabs and you don't have the staff only space behind the leading and trailing cabs lost to passengers?
More standing space but not as many seats.
 

Aictos

Established Member
Joined
28 Apr 2009
Messages
9,333
You can always use the door open button on the doors to open the door provided the driver hasn’t closed the doors....

The 717s are a massive step forward over the 313s which as much as I do like them, they are overdue a retirement!
 

jellybaby

Member
Joined
27 Dec 2012
Messages
329
You can always use the door open button on the doors to open the door provided the driver hasn’t closed the doors..
But if the door is already closed when the driver presses the door closed button you don't have the extra few seconds it takes for a door to beep and close while you jump in and reach back for your fedora.

The 717s are a massive step forward over the 313s which as much as I do like them, they are overdue a retirement!
Absolutely, I wouldn't swap a 717 for a 313. I'm just pontificating on what is different to me.
 

Aictos

Established Member
Joined
28 Apr 2009
Messages
9,333
But if the door is already closed when the driver presses the door closed button you don't have the extra few seconds it takes for a door to beep and close while you jump in and reach back for your fedora.
However if the driver hasn't closed the doors as I was trying to put across in my post then there's nothing stopping you from pressing the door open button to get on the train.

Absolutely, I wouldn't swap a 717 for a 313. I'm just pontificating on what is different to me.
Back when the 313s were introduced onto the Brighton services to Seaford, Lewes, Portsmouth etc, compared to the state of the GN 313s at that point I thought the Southern ones were the bees knees with 2+2 seating and a CIS onboard.

The fact that it's taken this long for the GN Inners to be upgraded is disgraceful but hey hopefully come May 2020 we can see the timetable take full advantage of the 717s, after all it's only taking 2 years!
 

387star

On Moderation
Joined
16 Nov 2009
Messages
5,909
700s were hated but seems these are better received
Sure they have Wi-Fi and charging points but perhaps the shorter journeys help and acknowledgment they could have gone for longitudinal seats
 

Mikey C

Established Member
Joined
11 Feb 2013
Messages
3,421
700s were hated but seems these are better received
Sure they have Wi-Fi and charging points but perhaps the shorter journeys help and acknowledgment they could have gone for longitudinal seats
The 717s were replacing clapped out 313s whereas the 700 were replacing on many routes, comfortable and still modern Electrostars!
 

Dave W

Member
Joined
27 Sep 2019
Messages
71
Location
North London
Definitely better - I use them for a mixture of commuting and leisure and I find them most agreeable. My perception is the teething troubles on introduction have mostly disappeared now.

Anecdata, I know, but I’d be left on the platform at Highbury 1 in every 3 or 4 trips on an outbound evening peak train before they came in. I’ve not been left behind once with a 717 - vast amounts of standing space.

And the plug sockets are an excellent addition - they should be in the spec for every train in the land.
 

yorkie

Forum Staff
Staff Member
Administrator
Joined
6 Jun 2005
Messages
48,253
Location
Yorkshire
I have split some posts here: https://www.railforums.co.uk/thread...tted-with-2-power-sockets-per-2-seats.195742/

If anyone wishes to post something that goes off on a tangent, please create a new thread.

If you see someone go off topic and wish to reply to it, please create a new thread, and report the first off topic post. Let us know in your report that you have created a new thread (and link to it if possible)

Thanks :)
 

choochoochoo

Member
Joined
6 Aug 2013
Messages
668
Has anyone else noticed the aircon kicking in/out when changing to/from ac/dc ?

Even in the cab, I've heard it changing after leaving/arriving at drayton park.
 
Status
Not open for further replies.

Top