Meridians and MML

[j0hn0]

Hi All

Does anyone know why the Meridians don't tilt?

I feel that the MML is certainly twisty enough for tilt to make a difference in journey times. Are there any planned upgrades for the MML apart from the Thameslink section that I use every day?

I might start commuting from bedford in the near future and was just wondering about the background of the line and services. 38 minutes is the top time to st pancras I believe.

cheers

 

[asylumxl]

Seeing as the plan has been to upgrade a large chunk of the line to 125mph running, I think it was deemed unnecessary.

Tilting isn't as simple as just fitting tilt. You'd need to install the necessary markers aswell. Aswell as this, most tilting trains tilt out of "normal" loading gauge, As such this would require work on lineside clearance which would further increase costs.

Check out the relevant RUS (route utilisation strategies) online, and there will be information on the planned upgrade. Unfortunately I am on my phone and can't post a link.

 

[Aictos]

Would it not mean making the interiors more narrower to fit the tilting equipment?

 

[sprinterguy]

Would it not mean making the interiors more narrower to fit the tilting equipment?

No: The bodyshells for the tilting and non-tilting Voyager/Meridian units all have the same profile.

And of course, the prescence of the tilt equipment dosn't affect the bodyshell as it is mounted below the vehicle body. It is the requirement for tilting trains to remain within the loading gauge envelope that causes them to have a greater taper or narrower body than some non-tilting stock.

 

[ChrisCooper]

No: The bodyshells for the tilting and non-tilting Voyager/Meridian units all have the same profile.

And of course, the prescence of the tilt equipment dosn't affect the bodyshell as it is mounted below the vehicle body. It is the requirement for tilting trains to remain within the loading gauge envelope that causes them to have a greater taper or narrower body than some non-tilting stock.

That's not true. I don't know about Voyagers but Pendolinos at least are out of gauge when fully tilted, hence the need for TASS to limit tilt and speed where it would be a problem.

Regarding the MML, the original plan was for tilting trains to replace the Turbostars. The problem is that the main section of the MML where tilt would have an effect is between Bedford and Leicester, but the stopping pattern of the Meridiens over this section is such that the benefits would be limited at best. On the other hand tilt equipment adds extra weight, a Super Voyager coach weights about 10t more than an equivalent Voyager coach, so acceleration would be effected. On the sort of services the Meridiens were intended to operate, with frequent stops, acceleration is important.

 

[sprinterguy]

That's not true. I don't know about Voyagers but Pendolinos at least are out of gauge when fully tilted, hence the need for TASS to limit tilt and speed where it would be a problem.

It's certainly a factor to consider when designing tilting trains, although the way I phrased that statement isn't entirely accurate: Allowances have to be made for the loading gauge with tilting trains, surely.

 

[LE Greys]

It's certainly a factor to consider when designing tilting trains, although the way I phrased that statement isn't entirely accurate: Allowances have to be made for the loading gauge with tilting trains, surely.

I believe that this was why APT did not need TASS, its body profile was even narrower than the Voyagers. So if TASS is unnecessary for Super Voyagers - which only tilt to six degrees IIRC, rather than the nine degrees of APT - why do they not tilt everywhere? The answer is probably that they do not really need to, since there are no EPS limits on any of the other lines they use. Personally, I would have left Super Voyager tilt on permanently, to reduce cant deficiency a little, but then I don't make the rules.

 

[Lampshade]

Personally, I would have left Super Voyager tilt on permanently, to reduce cant deficiency a little, but then I don't make the rules.

If it's not essential, it's just something to go wrong.

 

[LE Greys]

If it's not essential, it's just something to go wrong.

Well if it's there anyway, why not just leave it on all the time?

 

[ainsworth74]

Well if it's there anyway, why not just leave it on all the time?

It isn't at least not on XC 221s as it has been physically removed from the 221s.

Also where is the source for 221s not needing TASS in order to tilt?

 

[ChrisCooper]

I don't think Super Voyagers are actually out of gauge when tilting due to the narrower body profile than 390s and the 6deg tilt limit. TASS is still needed though as it also provides information to the tilt system about the corner coming up so the train can work out how much to tilt and when. APTs didn't need that as they used onboard accelerometers to calculate tilt required.

Using tilt to reduce cant defficiency is a bad idea as APT showed that too much tilt tended to cause passengers to become sick as they were not getting enough feel of the cornering which was conflicting with what they were seeing.

 

[DarloRich]

It isn't at least not on XC 221s as it has been physically removed from the 221s.

Also where is the source for 221s not needing TASS in order to tilt?

oh i didnt know it had been removed from the trains - i thought it had been isolated ( with a chuffing big bit of metal!)

 

[asylumxl]

oh i didnt know it had been removed from the trains - i thought it had been isolated ( with a chuffing big bit of metal!)

The equipment has been removed and big chuffing crossmembers welded in place .

 

[LE Greys]

I don't think Super Voyagers are actually out of gauge when tilting due to the narrower body profile than 390s and the 6deg tilt limit. TASS is still needed though as it also provides information to the tilt system about the corner coming up so the train can work out how much to tilt and when. APTs didn't need that as they used onboard accelerometers to calculate tilt required.

Using tilt to reduce cant defficiency is a bad idea as APT showed that too much tilt tended to cause passengers to become sick as they were not getting enough feel of the cornering which was conflicting with what they were seeing.

Can't they deal with that with software and accelerometers?

 

[Hydro]

Using tilt to reduce cant defficiency is a bad idea as APT showed that too much tilt tended to cause passengers to become sick as they were not getting enough feel of the cornering which was conflicting with what they were seeing.

The problem was APT was too good. The train was taking curves at speed and the tilt was actually taking all the lateral forces out of the equation, as it should. The passengers knew the train was taking a curve, but felt nothing at all. This apparently caused discomfort. The solution I believe was to drop the tilt back a little bit so the passengers felt slight lateral forces and what the eye saw and the body felt matched up a little better.

 

[Nym]

The equipment has been removed and big chuffing crossmembers welded in place .

Oh joy, so when ICWC starts more off route services and XC gets some IEPs to be able to cascade these back to ICWC it's going to take a hell of a lot of effort to be able to make them tilt again, well done arriva!

 

[j0hn0]

Cheers for the responses

so what is the top speed of the MML? Surely south of Bedford there are places at Luton/Flitwick/St Albans that could all benefit from a tilting train?

EMT trains certainly seem to dawdle through St Albans in the morning rush (at least compared to what I used to see at Rugby) and the fast thameslink to Bedford certainly doesn't feel much faster than 90mph.

If the MML could improve line speeds in the same way that the WCML did then towns like Bedford/Wellingbro/kettering could all grow in the same way that Rugby did not so long ago, and still is.

I personally find it very interesting to see how the 2 lines compare. eg, I have never seen any freight in the morning or evening rush, yet I've seen many on the WCML

Plus on WCML you are 6 tracked from Watford to Euston

 

[Hydro]

MML tops out at 110mph.

 

[talltim]

I beleive the 319s are 90mph max? The 317s were 100 mph, I can remember standing looking into the cab when they had two units coupled and seeing the speedo.

 

[ainsworth74]

so what is the top speed of the MML? Surely south of Bedford there are places at Luton/Flitwick/St Albans that could all benefit from a tilting train?

As Hydro says the MML currently tops out at 110mph but works are in hand to increase some sections to 125mph (sorry I'm not sure where exactly). Whilst tilting could be of some use on the MML it seems like it would be an unnecessary expense when 125mph running can be achieved by making alterations to the track layout and the signalling. To get tilt running on the MML you would need install TASS to the track as well as procure tilting rolling stock, remember 222s don't tilt and use different bogies to the 221s so it would require some significant work to retrofit tilt onto the 222s. I don't think it's a worthwhile expense when there are other ways of decreasing journey times.

I beleive the 319s are 90mph max?

Nope 319s are 100mph max.

 

[DarloRich]

The equipment has been removed and big chuffing crossmembers welded in place .

I thought the "chuffing" big cross memebers were to STOP it working - good old low tech solution. Need to nack something, whack a big bit of metal in! Perhaps i should transfer this to the "you lean something new every day thread"

BTW is "Chuffing" now a unit of measurement?

 

[MCR247]

Oh joy, so when ICWC starts more off route services and XC gets some IEPs to be able to cascade these back to ICWC it's going to take a hell of a lot of effort to be able to make them tilt again, well done arriva!

Hmm longer trains, less delays. Yes, thats obviously a bad idea :roll:

 

[222001]

The Midland Main Line will have sections of 125mph running all the way from East Midlands Parkway to London St Pancras. Most of the track between Bedford and London St Pancras is currently 110mph. The line through Bedford is also 110mph (to my knowledge).
Tilt would be of little, if any, use between Bedford and London as that is the straightest bit of the entire Midland Main Line. The corners are at Wellingborough, Kettering and Market Harborough. The speed in these corners is between 60-90mph, but again, these will be increased under the 125mph upgrade plans. In fact, looking at the documentation I have, nearly all, if not the entire line will at least have a speed upgrade of at least 5mph between East Midlands Parkway and London St Pancras

 

[Hydro]

"Corners"? CURVES! The only corner on the railway is Tattenham.

 

[ralphchadkirk]

"Corners"? CURVES! The only corner on the railway is Tattenham.

Didn't you know we have corners, bulbs in signals, and amber aspects?

 

[swt_passenger]

The intended MML speed upgrades are tabulated on page 143 of this:

http://www.networkrail.co.uk/documents/9816_EnhancementsDocumentMarch2011Update.pdf

(Large pdf though)

 

[j0hn0]

Great thanks all

 

[talltim]

"Corners"? CURVES! The only corner on the railway is Tattenham.

Dunno, there's some box near the vestibule doors on 158s with pretty sharp corners, I've got a scab on my head to prove it.

 

[asylumxl]

Dunno, there's some box near the vestibule doors on 158s with pretty sharp corners, I've got a scab on my head to prove it.