Selective speed limits

[Holly]

I recall reading that the speed limit over the Leftwich Viaduct could be raised if Pacers were banned from the route.

Is an alternative to have different speed limits over the viaduct for different types of roiling stock? Is this sort of thing done elsewhere?

 

[northwichcat]

What happened around 14 years ago Railtrack looked at Leftwich viaduct and said without any work to the track or viaduct the speed limit could be raised from 20mph to 50mph for 101s, Sprinters and 175s but could not be raised for Pacers and freight. At the time First North Western didn't have any intention of making the route Pacer free or timetabling certain services to be faster so that Pacers couldn't fill in, so nothing got done.

Yes there are differential speed limits on numerous lines. Parts of the WCML are 125mph for tilting stock and 110mph for non-tilting stock, while the Hope Valley line has sections which are 90mph for Sprinters and Turbostars and 75mph for 185s. There are other examples as well.

 

[edwin_m]

It's quite common for differential speed restrictions to be signed for different types of stock. For example only many of the "regional express" routes in the 90s, 158s were allowed to run at 90mph due to having features such as better braking than other rolling stock. And of course there are the EPS restrictions allowing tilting trains to run faster on the WCML. However I don't think any of the types of tran for which differential speed limits available includes Sprinters and not Pacers (the Rule Book and the Sectional Appendix each indicate that the other has this information!)

There are also some restrictions for specific train types that aren't provided with signs, just noted in the Sectional Appendix which the drivers must know about. As far as I'm aware these only apply to certain freight trains but others may know better.

 

[Senex]

Yes there are differential speed limits on numerous lines. Parts of the WCML are 125mph for tilting stock and 110mph for non-tilting stock, while the Hope Valley line has sections which are 90mph for Sprinters and Turbostars and 75mph for 185s. There are other examples as well.

On the WCML there are even odd examples of different speeds for Pendolinos and tilting Voyagers. On Trans-Pennine the Hope Valley, like the York-Scarborough line and the Selby-Hull line, is an example of where a good few years ago now Regional Railways on the introduction of the 158s managed to negotiate with the engineers a higher speed for the Sprinter stock.

At one stage there were differential limits for HSTs on the Newark to Lincoln line (and perhaps beyond Lincoln). And I am right in thinking that there were other places where HSTs were allowed the higher speeds in the past?

 

[najaB]

And I am right in thinking that there were other places where HSTs were allowed the higher speeds in the past?

Still are. For example between Edinburgh and Aberdeen there are differential speed limits pretty much all the way. Units e.g. 170s can use the HST limits as well, but loco hauled stock and freight cannot.

 

[kieron]

What happened around 14 years ago Railtrack looked at Leftwich viaduct and said without any work to the track or viaduct the speed limit could be raised from 20mph to 50mph for 101s, Sprinters and 175s but could not be raised for Pacers and freight. At the time First North Western didn't have any intention of making the route Pacer free or timetabling certain services to be faster so that Pacers couldn't fill in, so nothing got done.

Do you know what would need to be done to make this change? First North Western are long gone, and the ATW trains on the line (at least) are guaranteed not to be pacers.

If it was just a question of sticking up a few new signs one night when the line is closed anyway, updating a few documents and briefing the staff, wouldn't it have been done anyway?

These days, you'd want them to look at a few other classes of train, to see what limits need to apply when ATW North Wales-Manchester trains are diverted that way.

 

[Muzer]

There ARE differential speed restrictions. There are standard ones, which basically just involve a different speed restriction for passenger trains to freight trains. These are represented by the speed limit for freight trains, then a horizontal line, then the one for passenger trains underneath.

There are also so-called nonstandard ones, which have a different speed restriction for a given set of trains. There tend to be rules on what the different trains can be — if the cab interiors of two trains look very similar, but they would be subject to different speed restrictions, this can be disallowed. One example I was told of is Buriton Tunnel, which had a differential speed restriction of 40mph for HSTs (and everything else classed as an HST for speed restriction reasons, which is actually quite a lot of things) and 442s, and 70mph for everything else. This is because the tunnel has limited clearance, and 23m vehicles could collide while going around the curve if too fast. However, they had to remove this when Desiros came in, because 444s and 450s look too alike inside. At least, that's what I'm told. Someone correct me if I'm wrong!

 

[455driver]

One example I was told of is Buriton Tunnel, which had a differential speed restriction of 40mph for HSTs (and everything else classed as an HST for speed restriction reasons, which is actually quite a lot of things) and 442s, and 70mph for everything else. This is because the tunnel has limited clearance, and 23m vehicles could collide while going around the curve if too fast. However, they had to remove this when Desiros came in, because 444s and 450s look too alike inside. At least, that's what I'm told. Someone correct me if I'm wrong!

You are correct, it was a bit annoying to be on a late runner formed of 450s and having to slow for the 40 knowing full well the tunnel was good for 70 so you could make up a few minutes.

Saying that I do agree with he decision to limit all trains to the lower speed though.

 

[alexl92]

How restricted are the 185s on the route to Hull? The whole point of using 170s was to get around a speed restriction but then the turbos only ever operated a small number of services and the 185s have always worked certain Hull diagrams anyway.

 

[Muzer]

185s have very unfavourable speed restrictions. They don't come under any of the nonstandard speed classes; they don't even class as DMUs, last time I saw, presumably due to their weight. The only time they would generally get the faster speed restriction is for standard passenger/freight differentials

 

[The Planner]

Indeed, 185s are lardy things.

 

[Senex]

185s have very unfavourable speed restrictions. They don't come under any of the nonstandard speed classes; they don't even class as DMUs, last time I saw, presumably due to their weight. The only time they would generally get the faster speed restriction is for standard passenger/freight differentials

TPE seem to have form in this. When the 185s were introduced we were all told that it would only be a matter of time before they were duly authorised to take advantage of the higher differential speeds on TPE routes. It has never happened. And then we heard that in due course there would be a 110 authorisation for the 350s on the WCML, and of course that hasn't happened either. Bad planning and purchasing, or too easily led up the garden path ... ?

 

[The Planner]

Don't see why the 350s can't be sorted as LM have set a precedent, the 185s are a bit more of an expensive matter.

 

[northwichcat]

Do you know what would need to be done to make this change? First North Western are long gone, and the ATW trains on the line (at least) are guaranteed not to be pacers.

If it was just a question of sticking up a few new signs one night when the line is closed anyway, updating a few documents and briefing the staff, wouldn't it have been done anyway?

Maybe it relates to what edwin_m said earlier

However I don't think any of the types of tran for which differential speed limits available includes Sprinters and not Pacers (the Rule Book and the Sectional Appendix each indicate that the other has this information!)

These days, you'd want them to look at a few other classes of train, to see what limits need to apply when ATW North Wales-Manchester trains are diverted that way.

Apparently Network Rail told MCRUA they plan to do work to raise the speed for all traction when the signalling is next renewed.

 

[TDK]

The easy solution is to have an SP differential speed board, pacers are not sprinters could could not travel at the higher speed where sprinters and class 175's could (175's already have a special dispensation to run at SP and HST differential speeds) easy fix but the paperwork will take longer than implementing it.

 

[edwin_m]

The easy solution is to have an SP differential speed board, pacers are not sprinters could could not travel at the higher speed where sprinters and class 175's could (175's already have a special dispensation to run at SP and HST differential speeds) easy fix but the paperwork will take longer than implementing it.

Thanks for this detail - this is what I was failing to find in the standards and Rule Book.

I guess while there are still Pacers around, and a significant risk that a Pacer will turn up on a Sprinter diagram, there isn't much benefit in changing the speed because any time saving won't be reliably achieved.

 

[northwichcat]

I guess while there are still Pacers around, and a significant risk that a Pacer will turn up on a Sprinter diagram, there isn't much benefit in changing the speed because any time saving won't be reliably achieved.

I get the impression if a Pacer is significantly slower than a Sprinter it's kept off the route but if it's slightly slower the speeds/times for Pacers are used for both Pacers and Sprinters.

 

[plastictaffy]

Don't see why the 350s can't be sorted as LM have set a precedent, the 185s are a bit more of an expensive matter.

The 350's they have are already set up for 110mph running, whereas LM's early batches /1's and 2's, weren't. The /3's and 4's have always been uprated fro 110mph.

 

[MICHAEL FINCH]

I think that the pacers are a horrible unit and should have been gotten rid of years ago, every time I see one in action it is obvious how quite rightly they are nick named ( nodding donkeys ) they must be very uncomfortable to ride on, especially for anyone prone to travel sickness, and it cannot be very pleasant for the drivers of this old tat.

 

[edwin_m]

I get the impression if a Pacer is significantly slower than a Sprinter it's kept off the route but if it's slightly slower the speeds/times for Pacers are used for both Pacers and Sprinters.

I think that's so. Certainly working timetables show column headers for 14x and 150 but I think 150 and 156 are indistinguishable. Not sure about this route but if they are timed for Pacers anyway then the timetable couldn't take advantage of any speed increases.

Possibly, assuming Pacers disappear from Northern in 2019, they will be taken off the list of units cleared for the route. Assuming the restriction doesn't affect other stock types, it could then just be lifted for everything.

 

[kieron]

I guess while there are still Pacers around, and a significant risk that a Pacer will turn up on a Sprinter diagram

I don't think Arriva Trains Wales has any staff who know both Pacers and the mid-Cheshire line, meaning that they run no risk of this.

Even for Northern, there are some advantages in not timing absolutely everything on the assumption that you use your slowest available trains, particularly for a train which is scheduled to sit around for a while at the terminus anyway.

 

[northwichcat]

I don't think Arriva Trains Wales has any staff who know both Pacers and the mid-Cheshire line, meaning that they run no risk of this.

Even for Northern, there are some advantages in not timing absolutely everything on the assumption that you use your slowest available trains, particularly for a train which is scheduled to sit around for a while at the terminus anyway.

ATW have 1 service per day (Chester to Manchester Airport at around 03:30) which goes via the Mid-Cheshire line for route knowledge retention (except during engineering works) and that service has an excellent path where it doesn't get held anywhere. I'm not really sure ATW will care that much about 2 minutes coming off that service, it matters more for people travelling shorter journeys like Greenbank to Northwich where 2 minutes off would be a 40% time saving.

When ATW divert (or have ECS movements) they have to fit around other services which stop at all stations, so speeding up on one section may result in the service catching up the stopper further up.

 

[kieron]

I don't think Arriva would want this done for the time saving, but for the money. Slowing from 60 to 20 and then speeding back up again a minute later uses more fuel than only slowing to 50mph.

This isn't a lot of money each time, but it is 6 trains a week and does add up. If the cost of going from a situation where the viaduct is known to be suitable for a 175 at 50mph, but drivers are not permitted to take advantage of it, to one where they are allowed to do so, is also not a lot of money, it may be worth doing on this basis.

I'm not considering Northern here as I don't know if a sprinter journey would benefit much from the change when it's less than a mile from the next station in either direction.

 

[Joseph_Locke]

The reason why it has to wait for resignalling is probably because the signal spacing gives braking distances for Appendix A (freight) and Appendix B (passenger stock with normal braking) trains at a lower speed than that for Appendix C (passenger trains with enhanced braking) trains. Because Pacers are Appendix B passenger trains, but also come under the MU and SP non-standard differentials, there is no way of signing this.

Differential Speeds are nightmare to sort out, particularly since the guidance says we can only have three speed values on one post.

Class 185s are not covered by an MU differential just like Class 390s, but why is hard to get to the bottom of, and made odd by the fact that and HST can run at MU, despite actually being loco-hauled!

Sprinter (SP) speeds only cover a limited range of stock and they were only imposed to get round track construction issues, so no-one would suggest imposing a new one as an MU speed would allow a much wider group of trains to run faster (a class 185 can't run at SP or MU, or HST, CS, EPS come to that.)

 

[edwin_m]

Aren't 150s Appendix B braking as well?

 

[Joseph_Locke]

Aren't 150s Appendix B braking as well?

According to a handy chart I have, classes 121, 139, 14x, 150, 153, 155 and 156 are all Appendix B, as might be some class 319s (the ones that didn't get brake upgrades, but there is debate about which did and didn't, apparently).

However, Appendix B and C are pretty much the same below 75mph; and all the above can't exceed 75mph, IIRC. Of that list, only the 15x are eligible to operate under an SP speed, but the are all MU.