Glasgow - 75mph PSR after Eglinton St Jn

[Huntergreed]

This is just an observation, but I’ve noticed that almost every time I’ve used a WCML/Lanark/Edinburgh service that uses the up fast (via Cambuslang) line after Eglinton street junction, they almost always accelerate to reach 75mph immediately after the front of the train passes the board for the PSR (just after the overbridge carrying Cathcart road/the A728)

This may seem oddly specific, but it happens more or less every time I travel on this route (and on multiple TOC’s), leading me to ask: is there an easement/exemption from the rule that the rear of the train must have passed the PSR board before the train can accelerate at this particular location, or am I just unlucky?

 

[43066]

This is just an observation, but I’ve noticed that almost every time I’ve used a WCML/Lanark/Edinburgh service that uses the up fast (via Cambuslang) line after Eglinton street junction, they almost always accelerate to reach 75mph immediately after the front of the train passes the board for the PSR (just after the overbridge carrying Cathcart road/the A728)

This may seem oddly specific, but it happens more or less every time I travel on this route (and on multiple TOC’s), leading me to ask: is there an easement/exemption from the rule that the rear of the train must have passed the PSR board before the train can accelerate at this particular location, or am I just unlucky?

There’s no such thing as an exemption from PSR boards!

However, if every train you’ve been on is doing it, that’s a cast iron guarantee they aren’t speeding. Speeding does happen occasionally - usually involving E/TSRs not signposted properly (or not seen), or a couple of mph over for PSRs.

Not knowing the area at all, are you sure that’s the first PSR board?

Also, how can you be sure the rear hasn’t passed the board? It takes a surprisingly long time for trains to accelerate.

 

[Tempest Malice]

Chances are, the front reaching the 75 board lines up with the rear passing a previous board and accelerating up to it's limit isn't complete by the time the rear passes the 75 so you just experience it as one acceleration from the front of the train reaching the 75 board.

 

[Huntergreed]

The PSR in question that I'm talking about is the one featured at just before 00:04:40 in the following video:

The previous PSR's are gradual increases from 15mph to 30mph in increments of 5mph from Gantry A at central station to just before eglington street junction (where the PSR increases to 30mph). There's then a substantial leftward curve and a passage under the M74 motorway before the track straightens out, passes under the A728 (at the overbridge at 4:38), and then passes the 65/75 PSR board. I'm fairly confident this is the first board for this PSR, but every train I've been on, I've often felt the acceleration to beyond 30mph whilst still rounding the leftward curve before I've passed signal GR 738, and quite substantially before we pass under the A728! It does seem very unusual to me, but I've noticed this extremely often, and I can't think of a proper explanation for it!

 

[ComUtoR]

Come across from L1 at 25mph and onto the 30 for the up fast. Coast through the tunnel (signal sighting risk). Touch the 75 board and accelerate through it. I don't drive ScotRail but that's how I'd do it.

The 25mph onto the 30 and you're probably waiting to clear the points to accelerate anyway so just pull through the 75 board and nudge the last 5mph as you clear it.

== Doublepost prevention - post automatically merged: 19 Feb 2022 ==

leading me to ask: is there an easement/exemption from the rule that the rear of the train must have passed the PSR board before the train can accelerate at this particular location, or am I just unlucky?

Possibly but I don't sign the route to confirm/deny.

There’s no such thing as an exemption from PSR boards!

Boards may be placed at different locations. I am reminded of a tunnel or two on my patch where the boards are placed outside the tunnel but the speed increases before the PSR board.

 

[PG]

Just a thought - would there be any clue as to this contained in the Sectional Appendix?

 

[306024]

Here is the Scottish sectional appendix, see page 187 of 1126:

https://sacuksprodnrdigital0001.blob.core.windows.net/sectional-appendix/Sectional Appendix full PDFs/Scotland Sectional Appendix December 2021.pdf

Although related to a TSR, there is currently a long running trial in East Anglia where the train can accelerate once reaching the T board, without waiting for the whole train to clear. The TSR is for pedestrians sighting the train approaching, so once the front of the train has passed the crossing, the reason for the TSR has passed. From the East Anglia sectional appendix, page 15 of 532:

https://sacuksprodnrdigital0001.blob.core.windows.net/sectional-appendix/Sectional Appendix full PDFs/Anglia Sectional Appendix December 2021.pdf

Rule Book Module SP Section 3 – Temporary Speed
Restriction (TSR)
Trial introducing a new sign similar in its appearance and specification to the existing ‘T’ indicator but bearing the letter ‘A’ meaning ‘accelerate’ located underneath the ‘T’ indicator for the temporary speed restriction.
During the trial the Driver will be able to accelerate when the front of the train reaches the ‘A’ and ‘T’ indicators. Where the ‘A’ indicator is not visible the Driver will comply with Rule Book module SP and accelerate when the rear of the train passes the ‘T’ indicator.
During the trial the ‘A’ indicator may be removed and the trial suspended if:
• • an ESR is imposed over the same section of line,
• • where there is a consecutive TSR after the trial location or
• • where a complex TSR is introduced.
The trial involves the following level crossings:
EA1012 Ipswich to Trowse Jn.
Between Needham Market and Stowmarket Gypsy Lane LC – 77m64ch
Anglia Route GI - Dated: 17/08/19

 

[driver9000]

I sign the route but obviously I can only speak from how I work my trains at that location. In my experience most trains coast through Eglinton Street without really making an effort to accelerate to 30mph as it's a failing gradient anyway so you're not experiencing the trains speeding when the Driver takes power passing the 75 PSR board. I often find the signals at Polmadie are yellow too because there is a ScotRail train crossing over towards Rutgerglen so there's no point accelerating hard just to brake again because the signals are against me.

There is no easement for accelerating when the front of a train passes a PSR board but as mentioned above there are limited trials involving TSRs.

 

[Railsigns]

Although related to a TSR, there is currently a long running trial in East Anglia where the train can accelerate once reaching the T board, without waiting for the whole train to clear.

The TSR signage trials are taking place within various regions of Network Rail.

A trial of equivalent signage for PSRs is currently under way at Bristol Temple Meads.

https://www.railsigns.uk/sect13page6.html

 

[adamedwards]

Interesting to see the video and to my completely amateur eyes curious as to why there is such a long 75mph section before it increases to 85mph. Are there short signalling sections to increase capacity at the junctions around Polmadie? All of course points to an HS2 phase z tunnel to a through station under Glasgow and faster running to avoid all this in 2075!

 

[Watershed]

Interesting to see the video and to my completely amateur eyes curious as to why there is such a long 75mph section before it increases to 85mph. Are there short signalling sections to increase capacity at the junctions around Polmadie

The headway from Glasgow to Eglinton St Jn is 2 minutes, then it increases to 2½ mins up until Rutherglen East Jn, then 3 mins up until Carstairs (with a few exceptions).

It's pretty rare for a 75mph line to have a 2½ minute headway and, whilst not having all the exact signalling plans to hand, I suspect that maintaining this lower headway, during the most congested part of the route, is the reason for the linespeed staying at 75mph until just before Rutherglen East.

 

[43066]

Boards may be placed at different locations. I am reminded of a tunnel or two on my patch where the boards are placed outside the tunnel but the speed increases before the PSR board.

Come to think of it, Kidbrooke tunnel is one of them?!

 

[bengley]

I sign the route (that's my video posted above)

There is definitely no exemption to waiting for the train to clear the board

 

[Llama]

Summit Tunnel on the L&Y is similar, but there's a reduction in permissible speed which is signed at the entrance to the tunnel in the down direction. The actual reduction commences much further in advance, about 7/8 the way through the tunnel, at 16m 40ch which is about 24ch on approach to the east end of the tunnel. The board is most likely placed where it is for sighting reasons.

Not so far away on the East Lancs lines there's an increase in permissible speed from 20 to 40 on the Down East Lancs at Lydgate Viaduct, the 40 speed board is placed after the viaduct a few chains after the mileage of the speed increase, assumedly to avoid placing a post and the speed board on the actual parapet of the viaduct, there are houses below.

 

[Starmill]

Not so far away on the East Lancs lines there's an increase in permissible speed from 20 to 40 on the Down East Lancs at Lydgate Viaduct, the 40 speed board is placed after the viaduct a few chains after the mileage of the speed increase, assumedly to avoid placing a post and the speed board on the actual parapet of the viaduct, there are houses below.

I think that the Lydgate Viaduct is a known weak structure though isn't it? It has had temporary speed restrictions on it before now (and may do now, I don't actually know).

 

[Llama]

Not necessarily, it's not had a TSR for at least 8 years and I'm fairly sure even before then, there was a long-standing TSR through Holme tunnel and the whole route via Copy Pit seems to develop a new bump or dip every time there's a monsoon or drought but no TSR. The line speed is different each direction but as far as I am aware the down East Lancs has the 20 PSR due to earthworks issues on the approach to Lydgate Viaduct from the Burnley end (as evidenced by surveying markers) rather than the actual viaduct itself.

 

[Starmill]

Not necessarily, it's not had a TSR for at least 8 years and I'm fairly sure even before then, there was a long-standing TSR through Holme tunnel and the whole route via Copy Pit seems to develop a new bump or dip every time there's a monsoon or drought but no TSR. The line speed is different each direction but as far as I am aware the down East Lancs has the 20 PSR due to earthworks issues on the approach to Lydgate Viaduct from the Burnley end (as evidenced by surveying markers) rather than the actual viaduct itself.

Oh yes, that was it, it was actually the Portsmouth level crossing wasn't it that had a "temporary" restriction. However I did hear that work might have been in hand to improve it. It is interesting indeed that it's actually the hill alongside the line rather than the viaduct that's considered a cause of concern though.

Apologies for the digression.

 

[TrainSailing]

The PSR in question that I'm talking about is the one featured at just before 00:04:40 in the following video:

The previous PSR's are gradual increases from 15mph to 30mph in increments of 5mph from Gantry A at central station to just before eglington street junction (where the PSR increases to 30mph). There's then a substantial leftward curve and a passage under the M74 motorway before the track straightens out, passes under the A728 (at the overbridge at 4:38), and then passes the 65/75 PSR board. I'm fairly confident this is the first board for this PSR, but every train I've been on, I've often felt the acceleration to beyond 30mph whilst still rounding the leftward curve before I've passed signal GR 738, and quite substantially before we pass under the A728! It does seem very unusual to me, but I've noticed this extremely often, and I can't think of a proper explanation for it!

How do you know the speed of the trains you are travelling on? You may feel acceleration but this could be from say 20mph and by the time the train has gone beyond 30mph it is now beyond the 75 board?

 

[Deepgreen]

How do you know the speed of the trains you are travelling on? You may feel acceleration but this could be from say 20mph and by the time the train has gone beyond 30mph it is now beyond the 75 board?

This is the key question here - only the driver can know what the speedo says and GPS speed measurement systems used by passengers, for example, aren't to be relied upon. It's impossible to know for sure what the speed of the train is at any given moment without sight of the speedo. Yes, also, a PSR is a PSR, no exceptions. Specific PSRs for different types (e.g. EMU and loco) are signed accordingly.