Track layout between Newport and Cardiff

[MattWallace]

Hi all,

Completely new to a lot of this so have been reading the forums and lurking for a while, but thought I'd try and get an answer to something that's been bothering me on my daily commute!

Most of the track section between Newport and Cardiff is 4 tracks (apart from the various yards and spurs as far as I can tell) so I'm assuming that two are "slow" and the other two are "fast", with one of each in either direction.

My understanding is that the "up" line is the one heading towards London (told you I was new!) and therefore the "down" is heading in the opposite direction, however the tracks between NWP and CDF don't seem to be paired. As far as I can tell, they are laid out as follows:

DS | UF | DF | US

Is this "usual" for the rail network when running four tracks or is this to facilitate access to/from the yards?

Thanks in advance,

Matt

 

[Mojo]

You may be interested in this thread from earlier in the year, which discusses the various ways (and pros and cons) of the arrangement of the lines on multi-track sections, and also this one from 2012.

By the way, as this is the Great Western, the correct terminology is Main and Relief, not Fast and Slow

Between Newport and Cardiff, the track layout is UM DM UR DR. This continues for a bit to the east of Newport where the Bishton flyover takes the Up Relief over the Mains, leading to a track layout of UR UM DM DR.

 

[LNW-GW Joint]

Between Newport and Cardiff, the track layout is UM DM UR DR.

Just to be clear, I assume you mean between Cardiff and Newport?
(Mains on the north side).

 

[Envoy]

As I understand it, the 'Main' lines have a speed limit of about 95mph and the 'Reliefs' are about 60mph. Being as they both cross exactly the same country in almost a straight line, why should the 'Reliefs' be about 30mph slower than the 'Mains'? Surely, it would be beneficial to have the higher speed on all the lines between these two cities so that when the 'Mains' need maintenance, express trains can keep to schedule on the reliefs?

I also would have thought that 125mph would have been OK as there are no bends?

 

[louis97]

As I understand it, the 'Main' lines have a speed limit of about 95mph and the 'Reliefs' are about 60mph. Being as they both cross exactly the same country in almost a straight line, why should the 'Reliefs' be about 30mph slower than the 'Mains'? Surely, it would be beneficial to have the higher speed on all the lines between these two cities so that when the 'Mains' need maintenance, express trains can keep to schedule on the reliefs?

I also would have thought that 125mph would have been OK as there are no bends?

Its all down to track maintenance I think, in relation to the cost of maintaining both lines at 95mph. Given the relief lines are generally used by freight I could see why 60mph makes sense, even if it does mean a slightly slower journey time when engineering work is taking place.

I there are similar limitations that would be the reason for no 125mph running, although there are many other things that would effect that too, such as the signalling. Given that it would only be the HSTs that would do 125mph along there, I think it would cause more trouble having trains running at a mix of speeds 75, 90, 100 and 125mph - especially with the range of traffic you get along there.

 

[krus_aragon]

There are two common philosophies with regards to four tracking: slows/reliefs on the outside, or both slows on one side. As all the freight destinations between Newport and Cardiff (the docks) are south of the line, it makes sense to have all the freight lines on the south side as well.

 

[HSTfan!!!]

The track is quite capable of the higher speeds, I'm led to believe the speed difference is purely so there is an obvious difference in the type of line. The theory of the reliefs being on the south side due to that being where the industry is also what I was told when learning this section.
Not much point running at 125 for such a short distance, what with the local trains mixing in as well.

 

[D1009]

Historically the relief lines were used by many slow unfitted coal trains. So at the time multiple aspect signalling was first introduced in the 1960s, to maximise capacity the signals were placed closer together than is usual. Even now the normal line speed on the mains is 75 mph with a 95 dispensation for HSTs and other stock with superior braking. I stand to be corrected, but I believe the signalling on the reliefs is 3 aspect which is the reason for the lower line speed. This may well be changed when the area is resignalled.

 

[MattWallace]

Thanks all, this is fascinating stuff!

So if I've got this right, I should expect to travel on the "mains" (see, I'm learning! ) if on a 43/175 and the "reliefs" if on a 15x? Or are the reliefs mainly for the freight through that area?

One of the reasons I'm interested is that I quite often look out of the window at the yards as I go past to see what's sat there and it would be good to know if my view is going to be blocked by an "incoming" service

Thanks again,

Matt

 

[plastictaffy]

The track is quite capable of the higher speeds, I'm led to believe the speed difference is purely so there is an obvious difference in the type of line. The theory of the reliefs being on the south side due to that being where the industry is also what I was told when learning this section.
Not much point running at 125 for such a short distance, what with the local trains mixing in as well.

Would that be the same in other places, such as the WCML?? The signals have the same spacing, but for long distances, the track work is the same, but with a 110 (125 EPS) on the fasts, and 100mph on the slows. If they're good for the same speeds, why not have them set the same??

 

[ilkestonian]

The track is quite capable of the higher speeds,

Do you mean they are currently maintained to 125mph standards and signals are spaced for 125mph running, or that if Network Rail spent many millions on upgrades, then 125mph running might be possible subject to other traffic permitting?

 

[plastictaffy]

Thanks all, this is fascinating stuff!

So if I've got this right, I should expect to travel on the "mains" (see, I'm learning! ) if on a 43/175 and the "reliefs" if on a 15x? Or are the reliefs mainly for the freight through that area?

One of the reasons I'm interested is that I quite often look out of the window at the yards as I go past to see what's sat there and it would be good to know if my view is going to be blocked by an "incoming" service

Thanks again,

Matt

On my local route, freights share the slow lines (or Relief in your part of the world) with the local stopping services. We often get stuck behind freights, purely because the signaller has to get them out somewhere!! Some of our longer distance services do use the fast lines - usually the xx46, xx49 and xx13 off Euston, although the xx13 only uses the fasts as far as Ledburn Junction. (just south of Leighton Buzzard)

 

[Bald Rick]

The track is quite capable of the higher speeds

Sure of that? Not sure the track engineer would agree!

 

[krus_aragon]

Thanks all, this is fascinating stuff!

So if I've got this right, I should expect to travel on the "mains" (see, I'm learning! ) if on a 43/175 and the "reliefs" if on a 15x? Or are the reliefs mainly for the freight through that area?

The reliefs are mainly used for freight; almost all passenger services go along the main lines. I've enjoyed a few journeys from Cardiff to the Ebbw Valley on 150s: bombing it down the Up Main then slowing down for the trudge up the valley.

You will find some passenger services running along the relief lines, typically early or late night services, or on a Sunday. This is done on a regular basis so that drivers are still familiar with the route (maintaining "route knowledge") for any engineering work that closes the main lines, for example.

 

[MarkyT]

Just a quick word on the speed capability and differences between mains and reliefs. Often signal spacing for the highest possible speed can limit capacity for the more usual mix of train speeds, so a sensible compromise for the traffic mix is formulated. Sometimes with parallel signals on four track infrastructure, 3-aspect is used on the 'slows' and 4-aspect on the 'fasts'. I suspected that might be the case here but I was wrong.

I found a signalling notice for the final stage of the 1960s Newport resignalling, including the automatic section towards Cardiff

http://www.signallingnotices.org.uk/scans/4/1963 - W 1030 Newport Stage 7.pdf

This confirms that equally spaced 4-aspect was used on both pairs and is still there for the time being, so signalling itself is not a speed constraint on the slower relief lines compared to the mains. The speed limit according to the western sectional appendix is 60MPH for all traffic on the reliefs and 75MPH on the mains, but with a higher speed differential of 95MPH on the mains for HSTs only, with their better braking. Remember that HST brakes were designed to allow running at 125MPH without having to move signals (at great expense) on lines with signal spaced for 100 MPH. That better braking performance also applied through lower speed ranges, allowing some speed improvements on slower sections too, where desired as long as the track was suitable.

 

[louis97]

The track is quite capable of the higher speeds, I'm led to believe the speed difference is purely so there is an obvious difference in the type of line. The theory of the reliefs being on the south side due to that being where the industry is also what I was told when learning this section.
Not much point running at 125 for such a short distance, what with the local trains mixing in as well.

Even if the track is capable of a higher line speed, that would mean maintaining the line to the standard of a higher speed - therefore the lower speed allows a different level of maintenance.

Speed difference has no relevances to the need for a difference between the lines, there are sections of the WCML where the line speed is the same on the fast and slow lines.
--- old post above --- --- new post below ---

Thanks all, this is fascinating stuff!

So if I've got this right, I should expect to travel on the "mains" (see, I'm learning! ) if on a 43/175 and the "reliefs" if on a 15x? Or are the reliefs mainly for the freight through that area?

One of the reasons I'm interested is that I quite often look out of the window at the yards as I go past to see what's sat there and it would be good to know if my view is going to be blocked by an "incoming" service

Thanks again,

Matt

Generally only freight uses the relief lines, although there is some passenger services booked to use it throughout the day.
--- old post above --- --- new post below ---

The speed limit according to the western sectional appendix is 60MPH for all traffic on the reliefs and 75MPH on the mains, but with a higher speed differential of 95MPH on the mains for HSTs only, with their better braking. Remember that HST brakes were designed to allow running at 125MPH without having to move signals (at great expense) on lines with signal spaced for 100 MPH. That better braking performance also applied through lower speed ranges, allowing some speed improvements on slower sections too, where desired as long as the track was suitable.

The HST designation on speed boards is not limited to just HST sets, 158s, 175s and a few other trains are also allowed to do the higher speed too.

 

[plastictaffy]

Speed difference has no relevances to the need for a difference between the lines, there are sections of the WCML where the line speed is the same on the fast and slow lines.

There may be a very brief section at Berkhamsted, due to curvature, but there isn't anywhere else - not on the bit I sign, anyway. As an aside, there is a section of fast line on the WCML that actually has a lower speed limit than the slows. Any idea where and why??

 

[The Planner]

Colwich, S&C probably governs that.
--- old post above --- --- new post below ---

The HST designation on speed boards is not limited to just HST sets, 158s, 175s and a few other trains are also allowed to do the higher speed too.

158s and 175s match the appendix C braking curve so they can use the HST speed.

 

[plastictaffy]

The Planner - I was thinking much further south than that!!!
--- old post above --- --- new post below ---
I'm off to bed shortly - got nigh on 10 hours tomorrow - 0620-1600, so I'll tell you. It's Primrose Hill Tunnel. Fast line is 55mph, slow line is 75mph - coming down to a 40. The reason is the curvature of the fast line due the burial ground above. The tunnel goes round quite a tight right hander on entry, then comes round straight, then takes a left of a similar geometry to the right hander.
Anyway.......

 

[louis97]

There may be a very brief section at Berkhamsted, due to curvature, but there isn't anywhere else

I was thinking of between the line between Tamworth and Rugeley.

As an aside, there is a section of fast line on the WCML that actually has a lower speed limit than the slows. Any idea where and why??

Are we talking base line speed, or EPS too?
--- old post above --- --- new post below ---

The Planner - I was thinking much further south than that!!!

Much further south then!

 

[LNW-GW Joint]

JThis confirms that equally spaced 4-aspect was used on both pairs and is still there for the time being, so signalling itself is not a speed constraint on the slower relief lines compared to the mains. The speed limit according to the western sectional appendix is 60MPH for all traffic on the reliefs and 75MPH on the mains, but with a higher speed differential of 95MPH on the mains for HSTs only, with their better braking. Remember that

The Severn Tunnel-Newport section has already been resignalled so that is unlikely to change again in the near future.
Freight traffic was very heavy in the 1960s but is a shadow of itself now, and runs at a higher speed.
It would be good if local (75mph) traffic could use the Reliefs more, freeing up the Mains for 125mph IEPs.
It also affects the electrification plans - still nobody has confirmed whether the Reliefs are getting wired (on the grounds that they are only used for freight).
It would be very short-sighted not to wire them all the way from the Severn Tunnel.
I got the impression from somewhere that ground conditions played a part in the modest line speeds - much of the line is essentially over marshland.

Reading, until the recent changes, was one of those places where the Reliefs (75mph) had a higher speed through the station than the Mains (50mph), because of the lower curvature (and were the original route).
On the WCML the Down Fast has a 65mph turnout to the Stafford line at Colwich, while the Down Slow (used to be the Down Fast) is the "straight" route and can stick with the old 90mph.

 

[Envoy]

Many thanks to all who have responded about my query on the speed limits.

It has been mentioned that no decision appears to have been taken as to whether all 4 tracks between Cardiff and Severn Tunnel Junction will be wired. I would have thought that to get full value out of electrification, that it surely would be beneficial to have freights running on the GWML hauled by electric locomotives. However, what happens when they reach container terminals - like the one at Wentloog (east Cardiff)? How could the containers be lifted off trains if wires are in the way? Could the electric locomotives have small diesel engines as a back up for shunting through non-wired yards?

Presumably, if the reliefs are not wired, then the new Super Express Trains would have to run very slowly on the reliefs as they are going to be fitted with one? diesel engine for emergency use. (The Hybrid versions would of course, be able to run at full speed but I guess that those would not be in use on the south Wales route)?

I note that it has been suggested that a new station be built at St.Mellons* (east Cardiff). That being so, it would surely be built on the reliefs and therefore a higher speed limit on these lines must surely be justified.

* A new station at St.Mellons complete with a Park & Ride car park would mean that residents of east Cardiff could get by car or bus to services without the need to go to Cardiff Central. Those wishing to go directly east, at present, have the alternative of making the more lengthy trip by road to Newport. So, it would be probable that a St.Mellons station would prove highly popular, not just for the short distance hop into Cardiff Central but also for travel to/from Newport for transfer to long distance services. This would surely strengthen the case for all 4 tracks to be wired at once.

 

[NX]

From the Welsh portal to the Severn Tunnel to the station you have the UP/DN Tunnel lines, the at Severn Tunnel Junction the Main Lines UM/DM and DN Goods come in from Calidicot.

Just after the station you've got the (Tunnel to Cardiff Direction) DR/DM/UM/UR to Bishton Flyover the mains run double under the flyover, the relief lines run single either side, the UR goes over the top.

At Bishton Crossing the lines are DR/UR/DM/UM (relief lines the sea side of the railway). This continues all the way to Cardiff Canton area.

If you want releif line action on passenger trains then XX03 from Newport to Cardiff (FGW ex Taunton) are booked Reilef line from Llanwern West Junction via Platform one at Newport, to Cardiff, along with the 60 mph trundle.

The last week the 2154 Bristol to Cardiff and 2327 Cardiff to Bristol have run relief from STJ right through to Newport platform one then towards Cardiff. Due to engineering blocks on the mainlines.

The late night service from England to Wales are always good for releif line runs in both directions. Although I've yet to do the Bishton Flyerover.

NX

 

[MattWallace]

Thanks again all, this is excellent information and will make my commute a little less boring in future!

Cheers,

Matt

 

[brad465]

Having recently been along the line its 4 aspect on all tracks from what I saw, and new signalling is being installed ahead of electrification (judging by the gantry shape and knowing it will be electrified in the next few years

Are the new signals going to be spaced out more to account line speed increase? I imagine electric trains will automatically be able to run faster anyway nonetheless

 

[The Planner]

New signalling will be Cardiff end only, Severn Tunnel up to Newport has already been done and wont be touched.

 

[plastictaffy]

This is done on a regular basis so that drivers are still familiar with the route (maintaining "route knowledge") for any engineering work that closes the main lines, for example.

Nothing to do with route knowledge, as far as I know. If you sign a route, you sign a route.

 

[krus_aragon]

Nothing to do with route knowledge, as far as I know. If you sign a route, you sign a route.

Isn't there a need to 'keep current' on the routes you sign? Or does travelling just along the mains on a regular basis cover the reliefs as well?

 

[NX]

The only different aspect of the releif lines is the speed, the signals are all in the same places as the mains.

Patchway (the English limit of WROC control) and Marshfield'ish is all three aspect signalling, the former Newport and Cardiff panel areas are four aspect. But being converted to three, my understanding is that this reducing the number of times the driver gets AWS horns at yellow signals.

I've noticed that some of the new WROC signals (to be commissioned) around the Coedknewedd area outside Newport have very very minimal structures. One in particular will need a RRV with a raised platform to maintain, so once the wires arrive a isolation will be required ! Where as other new gantries have prospect platforms for maintence work to be carried out.

NX