Increase tolerances for cornering G force?

[SynthD]

This is why freight trains on very high speed lines such as HS1 is a dubious choice, as the curves are canted for 186mph and the freight will only run up to 90mph and is therefore almost permanently curving in cant surplus.

Have they done any higher speed trial runs? Is it economically uninteresting to the freight users of the Tunnel?

 

[Bald Rick]

This is because nobody has really wanted to run a non-tilt train above 110mph until recently, and Virgin wasn't going to give a leg up to a potential competitor so they were only interested in increasing the speed for tilting trains.

There are several fairly straight sections of the WCML, such as either side of Preston and around Lockerbie, where the geometry ought to allow a higher speed without tilt. I believe there's a project going on to investigate this further - it would also reduce journey times for future HS2 services.

We’ve covered this elsewhere.

HS2 looked at increasing the non tilt speds north of Wigan. That was a while ago, and IIRC no one is doing anything with that now. That’s not to say that it couldn’t be dusted off.

Avanti are currently looking at increasing the non tilt speeds Euston - Weaver Junction. I’m of the opinion that the answer will be ‘more challenging’ than Avanti are expecting. But we’ll see.

 

[edwin_m]

Have they done any higher speed trial runs? Is it economically uninteresting to the freight users of the Tunnel?

They'd probably need a lot of changes to the wagons to run any faster than that. In general freight wagons run at 75mph or less so even 90mph is unusual.

 

[brad465]

In the current franchise hiatus, TPE is hardly in a position to spend money to go faster than 110mph on the northern WCML.
397s could run at 125mph on the ECML or GWML if desired (and cleared for the route).
Whether passengers would enjoy the rough ride at that speed is another story.
Avanti wants to run its 80x units at higher speeds on the southern WCML, but that is a couple of years away at the least, and the franchise position is equally vague.

Yes that makes sense, especially given the RAIL edition in question was long before this year's events. Have they been tested on the GWML, as I can't see why else they would use it?

 

[Domh245]

Have they been tested on the GWML, as I can't see why else they would use it?

They haven't - only the WCML as far as I'm aware. GWML was given as an example of 125mph electrified railway but there is no intention to run them anywhere other than the current routes

 

[haggishunter]

Wasn't this tried on parts of the Far North Line a few years ago with raised linespeeds on slow twisty sections, rather than complaints from passengers the timetable ended up being made slower than at the start of the exercise because the 158s couldn't keep to the trial times? Or did it not ever get beyond being a discussion point?

 

[Deepgreen]

As others have said, it's not just about passenger comfort and safety, there is a major maintenance cost issue involved, both on track and wheels, apart from the myriad other areas where wear would increase. I remember in the 1960s and 70s speed limits were less rigorously observed than now, and countless times my train would enter a curve way too fast and the lateral forces were sometimes alarmingly strong! I remember one particular example on the Underground, when my R stock train entered Mansion House EB platform (over a left-facing set of sharp-ish points) and almost everyone standing was thrown to the floor - even some who were strap-hanging! On the West Highland line I also recall a SB run behind a 27 from Crianlarich where the brakes were very sparingly used - and we weren't even running late! Polystyrene coffee cups were sliding rapidly across formica tables - very different times!

 

[QueensCurve]

Hi,
I was wondering wether it is possible, practical or helpful to increase G-force tolerances for passenger rail services.

Most cornering forces are a fraction of that you get on say a bus, coach or even a plane.

The obvious answer is that passengers stand and move about on a train, but in my experience, the sudden jolts have a much larger impact on this than the G-forces involved in cornering. Plus, buses are always heavily accelerating, braking and cornering with standing passengers. Maybe it is worth studying in more detail, with adjustments in the speed corners come on, etc justifying how much lateral G force can be exerted on passengers.

Considering we are ditching tilting stock on a number of routes, and that HS2/3 will not reach as far north as some Northern/Scottish cities, would this be a useful consideration?

British rail increased the "cant deficiency" on which line speeds are based from 4.5° to 6° in the mid 1980s. The increase in cant deficiency brought BR into line with continental practice. Combined with 110mph running, led to a modest acceleration of of services on the WCML.

Even at the increased cant deficiency it remains a much more comfortable ride than on a bus. Long may it stay that way.

When flying an aeroplane the pilot flies a balanced banking turn using the rudder to keep the aircraft in balance. This prevents cornering forces on the passengers.

Above 6 deg, things start flying off tables - laptops, hot drinks, etc etc.

I experience that due to cant excess on Eurostar in February 2004 on a London to Paris service. We had a full stop - very briefely so likely due to poor regulation - at the end of the high speed line and the cups slid right off the table. We immediately restarted and immediately went into the channel tunnel.

 

[Wilts Wanderer]

I experience that due to cant excess on Eurostar in February 2004 on a London to Paris service. We had a full stop - very briefely so likely due to poor regulation - at the end of the high speed line and the cups slid right off the table. We immediately restarted and immediately went into the channel tunnel.

That sounds like poor table design as much as anything!

 

[a_c_skinner]

So are the MML and northern ECML are running with no complaints at a higher cant deficiency than the WCML? What no one seems to be able to quantify is how much time is saved with tilt if one were to allow this higher cant deficiency on the WCML. I suspect not much and I doubt we will see any more tilting trains ordered for the UK.

With more non-tilt stock on the WCML this nettle needs to be grasped.

 

[Jan]

I think DB have been 150 + 150 (cant + deficiency) for many years. It was certainly that back in the 1970s.

Regular value for cant deficiency is 130, 150 being the exceptional value, and I've only recently come across some article noting that values > 130 so far don't seem to have been utilised a lot in practice (the article did go into a bit more details, but I'd have to dig it out and reread it again in order to be able to give a somewhat accurate summary).

 

[Wapps]

To allow non-tilt (HS2) stock to run at 125 on the WCML, for one?

It would be so much easier to just procure tilting stock for Avanti and HS2. As I’ve said in other forums, we seem to be re-inventing the wheel. The tilting infrastructure is there, we just need the (next generation of) trains to have tilt.