MML Line Speed Improvement Campaign

[TheNewNo2]

The St Pancras to Sheffield Line Speed Improvement Project has been running for the past 2 years to my personal knowledge. It has not been "paused" like the MML Electrification. A lot of work has been completed, level crossings closed, track alignments altered, signalling alterations undertaken. One of the problems is the relatively poor braking curve of an HST compared to a 222 so differential speeds have had to be imposed. Many millions of pounds have already been spent for a few minutes gain.

I thought the whole reason the HSTs were on the stoppers was that they had better braking/acceleration profiles than 222s.

 

[AM9]

I've heard it all now. HSTs are "slow accelerating old trains".

Oh the innocence of youth? However did we survive the ordeal of a Black 5 with 9 on leaving Wellingborough on the up? (I was too young to experience the pure torture of the compounds.)

How can you be disbelieving of comments from those that regularly travel on the MML when you openly admit in post #13 "But I do not use MML regularly -", you clearly have not had much experience of just how slow the HSTs do regain linespeed when checked or after a station stop.
It's one thing looking at maximum speeds and distances in the relatively quiet parts of the MML then making assumptions of how little time a journey could take. But the reality of overall MML service is as several here have said, i.e. For the first 50 miles out of St Pancras, the 5 MML timetabled trains per hour share track access with 4 trains to Bedford, 2 trains to Luton, 2 trains to St Albans and 2 to West Hampstead Thameslink, which is the 13:00 - 14:00 off peak passenger timetable. Then add the potential congestion caused by the terminators, MML ECS movements at St Pancras and Thameslink at Bedford, plus somewhere in there there are typically 3-4 freight paths which may be taken up.
With all that, mostly the timetables are kept to within 3-5 minutes. The EMUs just nip in and out of the fast lines in their slots. When a MML service is delayed in its path, the speed drops and (particularly the HSTs) struggle to get back up to speed, which means that they are then the obstruction for the EMUs. Somehwere, I've seen a you tube video taken from a 319 whis departed at the same time as an HST. The 319 (on the slow line) was travelling at around 50mph before the HST started to catch up, (just in time to slow down for the next signal check).

 

[Hairy Bear]

I thought the whole reason the HSTs were on the stoppers was that they had better braking/acceleration profiles than 222s.

No it,s the other way round. A 222 will out brake and out accelerate a Hst.
The Hst are on the early morning and peak time trains to do the serious shifting of passengers during the peak. They will be with us until electrification and replaced by cl.800,s ?.

Long live the Hst,s horray !

 

[Joseph_Locke]

I thought the whole reason the HSTs were on the stoppers was that they had better braking/acceleration profiles than 222s.

A 2+7 class 253/254 has 500bhp per vehicle; a 222 has 750bhp - even if the 222 weighed as much as the 253/254 (unlikely), then a 222 still wins.

 

[AM9]

A 2+7 class 253/254 has 500bhp per vehicle; a 222 has 750bhp - even if the 222 weighed as much as the 253/254 (unlikely), then a 222 still wins.

And of course their power is put down through 50% of the 222's wheels whereas an HST only ever drive 16.7% or 18% of axles on 2+8 and 2+7 respectively so initially, adhesion can be an issue.

 

[Philip Phlopp]

A 2+7 class 253/254 has 500bhp per vehicle; a 222 has 750bhp - even if the 222 weighed as much as the 253/254 (unlikely), then a 222 still wins.

I'm sure many of us can still remember the timetabling chaos that ensued in the first few months of the (Arriva) CrossCountry franchise when the ex MML HST sets were introduced without the diagrams being re-timed accordingly.

It was a regular occurrence to see sets running 15 or 20 minutes late, despite it being readily obvious after looking through TRUST that there were no delays and no issues with the stock, they were keeping up with the other HST stock on the ECML, GWML and MML, but couldn't get close to the Cl.22x timings.

 

[Senex]

The EMUs just nip in and out of the fast lines in their slots. When a MML service is delayed in its path, the speed drops and (particularly the HSTs) struggle to get back up to speed, which means that they are then the obstruction for the EMUs.

Things must have improved since the time - quite a few years back now - when I was regularly using the MML. My routine experience (and I have the records to prove it) was of leaving St Pancras on time on a down Sheffield only to be brought almost to a stand before Harpenden whilst a late-running EMU got out of the way on to the slow. The lost time could not normally be recovered. In the up direction checks from the EMUs crossing over were much more varied, but a regular bad location was Kempston Road. Another very regular bad performer was the up non-stop morning service from Leicester which routinely stopped at Watling Street so that an EMU could cross to the down fast in front of it at West Hampstead.

 

[Hairy Bear]

Things must have improved since the time - quite a few years back now - when I was regularly using the MML. My routine experience (and I have the records to prove it) was of leaving St Pancras on time on a down Sheffield only to be brought almost to a stand before Harpenden whilst a late-running EMU got out of the way on to the slow. The lost time could not normally be recovered. In the up direction checks from the EMUs crossing over were much more varied, but a regular bad location was Kempston Road. Another very regular bad performer was the up non-stop morning service from Leicester which routinely stopped at Watling Street so that an EMU could cross to the down fast in front of it at West Hampstead.

Still happens. They hold us up ,we hold them up.Cross Country holds the whole country up !
.

 

[muddythefish]

Judging by my last 3 journeys into London, increasing line speed will just break the track. The fasts from St Albans to StP are in a terrible state, if you sit over the bogie you hear and feel large thumps (rail misaligned) and are shaken violently, frequently.

You're not the only one who's noticed it. I can't pinpoint exactly where but somewhere around Hendon RAF Museum the 387s rock and lurch violently. I certainly wouldn't like to be drinking a cup of tea as it would go all over the place.

 

[asylumxl]

I had exactly that experience on a 387 last Thursday. Not only bottoming but hard side shifts particularly pst Mill Hill. There weren't even any points around those spots. I wonder how the 700s will handle the track shortfalls with their short wheelbase bogies. We've got used to ageing 319s rattling along the fasts at near maximum speed but the Electrostars should fare better, - especially the 387s which are all less than a year old!

I believe the rough ride is a result of (to put it nicely) sub-optimal transitions between the different gradients on the way south. I'm not sure if this is down to poor track design or poor track laying though. I find the Meridian's somewhat wallowy ride absorbs the bumps quite well.
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You're not the only one who's noticed it. I can't pinpoint exactly where but somewhere around Hendon RAF Museum the 378s rock and lurch violently. I certainly wouldn't like to be drinking a cup of tea as it would go all over the place.

In the case of the curve at Hendon, I'm not sure that's entirely down to bad track quality.

It might be down to the cant of the track being designed for a higher speed (e.g. 110mph), it could be due to hunting oscillation of wheel sets or it could be due to a combination of things.

The dynamics of the rail/wheel interface are a rather complicated subject..

 

[70014IronDuke]

I don't understand, are you making a joke or being patronising?

Ah, I suppose this does not come over properly in a written forum. (need to sit around the pub table)

I was being self-ironic, I suppose - yes, I realise in fact the HST is 40 years old, and is out performed by a 222 - but to me, in spirit, it is still a super modern, high-powered train.
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How can you be disbelieving of comments from those that regularly travel on the MML ...

Misunderstanding. I am not.

...
-"[/I], you clearly have not had much experience of just how slow the HSTs do regain linespeed when checked or after a station stop.
...
With all that, mostly the timetables are kept to within 3-5 minutes. The EMUs just nip in and out of the fast lines in their slots. When a MML service is delayed in its path, the speed drops and (particularly the HSTs) struggle to get back up to speed, which means that they are then the obstruction for the EMUs. Somehwere, I've seen a you tube video taken from a 319 whis departed at the same time as an HST. The 319 (on the slow line) was travelling at around 50mph before the HST started to catch up, (just in time to slow down for the next signal check).

Yes, thanks for the detailed explanation. I can understand this intellectually - I just have to catch up emotionally that the HST is relatively underpowered compared to the competition ! :roll:

 

[Bald Rick]

I believe the rough ride is a result of (to put it nicely) sub-optimal transitions between the different gradients on the way south. I'm not sure if this is down to poor track design or poor track laying though. I find the Meridian's somewhat wallowy ride absorbs the bumps quite well.
--- old post above --- --- new post below ---


In the case of the curve at Hendon, I'm not sure that's entirely down to bad track quality.

It might be down to the cant of the track being designed for a higher speed (e.g. 110mph), it could be due to hunting oscillation of wheel sets or it could be due to a combination of things.

The dynamics of the rail/wheel interface are a rather complicated subject..

It's a regular bad spot. Underlying issue, not the track itself. Pway know about it.

 

[asylumxl]

It's a regular bad spot. Underlying issue, not the track itself. Pway know about it.

I assume you are talking about between the tunnel portal and Mill Hill Broadway?

If you don't mind me asking, what is the underlying issue?

 

[Bald Rick]

I assume you are talking about between the tunnel portal and Mill Hill Broadway?

If you don't mind me asking, what is the underlying issue?

Yep. The stuff that underlies the track.

 

[asylumxl]

Yep. The stuff that underlies the track.

Oh, so it's an issue with the tectonic plates?

 

[najaB]

Oh, so it's an issue with the tectonic plates?

Or one of the elephants (or the turtle...)