Scotrail InterCity 125 (HST) units, do they actually run at 125mph?

[Choo choo 66]

Yes, but my point is that this doesn't apply for ex-FGW sets as the power cars do not brake at the same rate as trailers. Not in the same way as the original HST set up with the two-stage brake but enough that GWR restrict 3-car Castle sets to 90mph for instance.

Pretty sure gwr 2+3 sets are permitted to do 100

 

[John Bishop]

Just wondered, fastest they run on my local line (Dyce to Aberdeen) is 75mph.... and that's only for probably 3 or 4 miles. Seems such a waste.

It’s 75mph all the way to Inverurie and from outside Keith all the way to Inverness, quite a bit longer than 3 or 4 miles as you say.

 

[brad465]

Yes, but my point is that this doesn't apply for ex-FGW sets as the power cars do not brake at the same rate as trailers. Not in the same way as the original HST set up with the two-stage brake but enough that GWR restrict 3-car Castle sets to 90mph for instance.

I once got a 3 car Castle set in August from Bridgwater to Taunton and couldn't understand why they are run like that, unless there was a Mk3 shortage, as I thought they were all 4 car, or if 3 cars a 158/165/166 would operate it (I thought it would be one of them when the departure display said (formed of 3 coaches).

Are there any plans to increase the Scotrail HST sets to 5 coaches, which was being talked about before (although I wouldn't be surprised if Covid has made that redundant for a while)? If length is a problem in running above 100mph an extra coach would in theory allow higher speeds than that, but, as has been mentioned, they'd have to operate south of Edinburgh/Glasgow, and/or there would have to be plans to upgrade some 100mph stretches within the Central Belt.

 

[Deltic1961]

Apparently 5 car sets being introduced in this months timetable change.

 

[najaB]

Are there any plans to increase the Scotrail HST sets to 5 coaches, which was being talked about before

Most of them are being extended to 5 carriages. You should see a lot more of them from the timetable change.

 

[Ken H]

I am going back a little now but dont trains going above 100mph need double manning? or has that gone?

 

[scotraildriver]

Only 4 being extended according to the Scotrail website. Weird .

 

[Mag_seven]

I am going back a little now but dont trains going above 100mph need double manning? or has that gone?

Went years ago.

 

[Ken H]

Went years ago.

thanks

 

[hexagon789]

I think you are correct. Although drivers understand the different braking performance of the various traction they sign, minimising the effect of different train formations is good practice.

Well then, thats far more logical a set up than it originally seemed.

Also short form HST sets are unlikely to be operating on routes requiring significant high speed running.

I suppose so, though you had GC with their 2+5 sets covering a fair mileage at up to 125mph speeds for some years.

And while GWR and SR might not do those speeds, both have not insignificant 100mph running.

Really, I never knew that!

I was replying to your "I haven't read of other TOCs being affected though.", which confirms that it didn't affect at least one other operator.

I think I misunderstood what you meant, sorry

The 385's do 0-60mph in around 44 secs compared to around 64 secs for a 2+4 HST. But the 60mph to 90mph time shows the HST's superiority once rolling - 50 seconds vs 60 secs for the 385. I measured 0 to 99mph in around 2.5 mins for both. What's interesting here is the Class 385's superior start gives it around a 20 second advantage from rest to 2.5 miles over the HST. Both limited to 100mph though! One of the issues for the HST is the slow releasing brakes compared to a unit, and the fact drivers can't give them full power from a start.
I'd love to see what the MTU's connected to a modern AC drive would achieve.

Interesting how the 385s compare to the short HSTs and vice-versa. I'd have expected the 385 to have superior performance not just from a stand but right through the speed range. The fact that the HSTs do better in the upper speed range is interesting, because I would have thought the way the amps really begin dropping off at 70mph+ would have equated to a noticeable drop in performance while the straight electric 385 I presumed could rely on sustained motor performance.

Pretty sure gwr 2+3 sets are permitted to do 100

I'm just going with what I was informed of:

0-2 trailers: 75
3 trailers: 90
4 trailers: 100
5 trailers or more: 125

I am going back a little now but dont trains going above 100mph need double manning? or has that gone?

Went at privatisation. BR negotiated to 110mph, GWT & GNER negotiated the full 125.

Apparently 5 car sets being introduced in this months timetable change.

They've already been introduced.

Only 4 being extended according to the Scotrail website. Weird .

Where does it say that?

 

[scotraildriver]

 

[najaB]

Only 4 being extended according to the Scotrail website. Weird .

I saw that too but assumed it was a mistake. The plan was (if I remember correctly) all bar four would be extended to five carriages. The four-carriage sets being largely confined to Inverness-Aberdeen services.

 

[CEN60]

Every 25mph quicker you travel, you save *roughly* 10 seconds per mile.

75mph = 48 seconds per mile
100mph = 36 seconds per mile
125mph = 29 seconds per mile

75mph to 125mph means saving around 20 seconds a mile, which, by the time you factor in the longer acceleration and braking, you end up no better off than when you started on services that stop every 10-20 minutes.

So take a straight set of line, say a classic example like St Madoes to Monorgan (between Perth and Dundee). 90mph throughout, and 10 miles long. If you wanted to increase that to 125mph, which is perfectly doable on that alignment, you'd need to factor in the additional time to accelerate and brake. Given the line-speed transitions, set this at, say, 1 mile such that 125mph is covered across 9 miles.

90mph = 40 seconds per mile = 40 x 10 = 400 seconds
125mph = 29 seconds per mile = 29 x 9 = 260 seconds
----
= ~2.3 mins journey saving time between Perth and Dundee on current timings

Aberdeen to Dyce line max speed stretches (3 miles)...

75mph = 48 seconds per mile = 48 x 3 = 144 seconds
125mph = 29 seconds per mile = 29 x 3 = 86 seconds
----
= ~1 min journey saving time between Aberdeen and Dyce (assuming you could raise all speed limits with a max of 125mph on current 75mph stretches)

The cost to upgrade that infrastructure to 125mph would run into the tens of millions. Whereas you can introduce faster accelerating rolling stock which can off-set at least a minute in the very same journey time without the upgrades, which is exactly what ScotRail have done with short HSTs vice 170s/158s. The same applies to Glasgow to Edinburgh, where a 385 can cover all stops between Waverley and Queen Street in exactly the same time as it would have taken a 170 to run semi-fast with calls at Haymarket, Falkirk High, and Croy.

Moral of the story? Upgrading existing line speeds isn't as promising as it seems for short stretches of diesel lines.

In the example of Dyce to Aberdeen, the best investment that can be made to decrease journey times isn't raising line speeds on existing alignments in most cases. Instead it is by electrifying the lines so that acceleration can off-set line speed upgrades. Ie, a 385 would cover Aberdeen to Dyce slightly quicker than a 4-car HST, at a much lower operational cost. Just like how a HST can cover the same journey quicker than a 170/158, albeit at a much higher operational cost.

"All" of the curvature will not support 125mph between Aberdeen and Dyce.
And for the record - 75mph is your max between Dyce & Inverurie. Again there are quite a few curves that limit the speed to 75mph

 

[Deltic1961]

So why did Scotrail spend all that time and money refurbishing 70s and 80s units when more up to date trains could carry out essentially the same job?

It's a gamble at Dyce whether it will be a 4 far HST or a 2 car 170 so why bother with the HST at all?

 

[The exile]

I once got a 3 car Castle set in August from Bridgwater to Taunton and couldn't understand why they are run like that, unless there was a Mk3 shortage, as I thought they were all 4 car, or if 3 cars a 158/165/166 would operate it (I thought it would be one of them when the departure display said (formed of 3 coaches).

Are there any plans to increase the Scotrail HST sets to 5 coaches, which was being talked about before (although I wouldn't be surprised if Covid has made that redundant for a while)? If length is a problem in running above 100mph an extra coach would in theory allow higher speeds than that, but, as has been mentioned, they'd have to operate south of Edinburgh/Glasgow, and/or there would have to be plans to upgrade some 100mph stretches within the Central Belt.

Think the GW 3 car castle was a temporary measure making use of what was available at the time

 

[JamesT]

So why did Scotrail spend all that time and money refurbishing 70s and 80s units when more up to date trains could carry out essentially the same job?

It's a gamble at Dyce whether it will be a 4 far HST or a 2 car 170 so why bother with the HST at all?

Because there aren't enough 170s in the UK for every franchise that wants them to have them. If Scotrail were running their full pre-Covid timetable as planned they would need the HSTs to provide enough capacity.

 

[Deltic1961]

OK, thanks.

 

[najaB]

So why did Scotrail spend all that time and money refurbishing 70s and 80s units when more up to date trains could carry out essentially the same job?

Because there weren't enough DMUs to go around and it's too early in the Scottish electrification process for it to make sense purchasing bi-modes.

 

[plugwash]

So why did Scotrail spend all that time and money refurbishing 70s and 80s units when more up to date trains could carry out essentially the same job?

Between the withdrawl of all the pacers and many of the 153s* due to politics and/or PRM, the fact that most high-profile "full fleet replacement" programmes have been on electrified lines or London mainlines and general gorwth in passenger numbers (pre-covid) there hasn't exactly been a ready supply of local/regional DMUs for operators to choose from.

Now one way around that is to order new, but there are problems with that, firstly that it takes years from placing the order to actually receiving the trains. Secondly ordering diesel rolling stock for lines you hope to electrify soon isn't exactly a smart move. Bi-modes are an option but tend to be towards the expensive end.

So you end up with intercity stock freed up by the intercity express programme and it's offshoots being used for regional work to make up the numbers until a long term plan comes together.

* TFW did some PRM conversions but at a heavy price in passenger capacity. Scotrail also had a few converted as "bike/baggage vans". Other than that I think the 153s still in service are not PRM compliant and very much on borrowed time.

 

[Peter Mugridge]

I saw that too but assumed it was a mistake. The plan was (if I remember correctly) all bar four would be extended to five carriages. The four-carriage sets being largely confined to Inverness-Aberdeen services.

Could it simply mean four entering service in five car formation on this date ( with the rest to follow later )?

 

[Steven_G]

Because there weren't enough DMUs to go around and it's too early in the Scottish electrification process for it to make sense purchasing bi-modes.

It is also Scotrails response to the rival operators 800’s running Glw/Edi north and taking revenue away. Modern luxury travel v Turbostar…… what would you choose?

 

[alangla]

In what way is 75/100mph ”a waste”?

It’s more 4500hp and 35m or so of unusable train (and platform) length in a 100mph, 4/5 car train that’s the real waste. Still think it’s insane, given diesel prices both at the current time & the recent past, that there wasn’t a mod done to allow one of the power cars to stop & start its engine while on the move.

 

[Clansman]

It’s more 4500hp and 35m or so of unusable train (and platform) length in a 100mph, 4/5 car train that’s the real waste. Still think it’s insane, given diesel prices both at the current time & the recent past, that there wasn’t a mod done to allow one of the power cars to stop & start its engine while on the move.

To add insult to injury, the interior specs by ScotRail for the Mk3s don't exactly provide much of an increase in standard class seats vs a DMU. I had an Inverness 158 from Aberdeen to Glasgow recently and must say I am starting to prefer them over the HSTs.

"All" of the curvature will not support 125mph between Aberdeen and Dyce.
And for the record - 75mph is your max between Dyce & Inverurie. Again there are quite a few curves that limit the speed to 75mph

I'm fully aware of the constraints of that line. I was more so highlighting the OP's point that even if you were to somehow get the speed up on current alignments, that even 125mph wouldn't make much of a meaningful difference in journey times.

 

[Prestige15]

The shorter carriage sets aren't permitted to run at 125 mph anyway as they have insufficient brake force. I don't necessarily view it as a waste - yes, they're now working in a role where their full capability isn't required, but it doesn't minimise the fact that in their previous roles that high-speed capability was relied upon for many years.

Grand Central/Hull Trains/Network Flying Banana use to run the HST in 4/5 car formation at 125mph

 

[dodecahedron67]

I had an Inverness 158 from Aberdeen to Glasgow recently and must say I am starting to prefer them over the HSTs.

What are the differences between a regular 158 and an Inverness 158? Is it just the seating? (sorry for off topic)

 

[Railperf]

To be fair - the biggest constraint regarding journey times seems to be single line running and the fact that trains have to wait in loops for those coming in the opposite direction. As the loops are not exactly equal distance apart - there can be a fair amount of waiting time at each loop - especially if the oncoming service is running late. Add to that many loops are still on an older signalling system that does not allow simultaneous entry of trains from both directions into the stations. A couple of Highland line loops were resignalled to allow this - notably Pitlochry and Aviemore. But the loops at Kincraig, Carrbridge, Moy and Tomatin only seem to allow one train movement at a time.
If you were going to increase linespeeds - closer to 90mph might make a difference and resignalling the loops to allow simulataneous arrivals.

 

[TrainTrackJack]

I'd love to see what the MTU's connected to a modern AC drive would achieve.

Google ‘Saturn V Rocket’ for a good comparison

 

[Clansman]

What are the differences between a regular 158 and an Inverness 158? Is it just the seating? (sorry for off topic)

ScotRail's 158 fleet is split between 2 depots, Inverness and Corkerhill (formerly Haymarket). With the exception of the Far North line (which require RETB signalling which only the Inverness units are fitted with), they run interchangabley on all other routes 158s operate.

Difference between them is the high refurbishment standard. Inverness 158s were refurbished in the First days ~2007 to a very high standard, whereas the Haymarket (now Corkerhill) sets were left untouched. In recent refreshes the Inverness sets just got the new colour scheme touch up and a deep clean as well as a few minor modifications. Recently, the Corkerhill sets were refurbished, but not to the same standard, leaving a difference between the 2 in terms of seating provision, ambience, luggage space, legroom, and bike space.

Whilst it's up for debate which of the two are better, some (including myself) would argue the Inverness 158s are better than a ScotRail HST for standard class (bigger tables, greater legroom, more toilets, greater luggage and bike space, USBs provided in addition to plugs).

 

[najaB]

Google ‘Saturn V Rocket’ for a good comparison

I like the idea, but as an amateur space-nerd (and professional pedant ) it's not the best analogy. The Saturn V was slow off the mark (it took more than 10 seconds to clear the tower), I think a MTU plus modern AC would be more like a solid rocket (e.g. Polaris).

 

[dodecahedron67]

ScotRail's 158 fleet is split between 2 depots, Inverness and Corkerhill (formerly Haymarket). With the exception of the Far North line (which require RETB signalling which only the Inverness units are fitted with), they run interchangabley on all other routes 158s operate.

Difference between them is the high refurbishment standard. Inverness 158s were refurbished in the First days ~2007 to a very high standard, whereas the Haymarket (now Corkerhill) sets were left untouched. In recent refreshes the Inverness sets just got the new colour scheme touch up and a deep clean as well as a few minor modifications. Recently, the Corkerhill sets were refurbished, but not to the same standard, leaving a difference between the 2 in terms of seating provision, ambience, luggage space, legroom, and bike space.

Whilst it's up for debate which of the two are better, some (including myself) would argue the Inverness 158s are better than a ScotRail HST for standard class (bigger tables, greater legroom, more toilets, greater luggage and bike space, USBs provided in addition to plugs).

Ta!