Intercity Express Programme (IEP) - ongoing discussion

[whole diary]

[JayMac]

Could 2+9 or 2+10 climb Rattery Bank after a standing start from Totnes?  I know the 2+9s used on the Summer Newquay services do - but they are not booked to call at Totnes.

If 2+9 at least is cleared for the route then I'd assume (dangerous, I know!) they'd be fine starting from Totnes. After all there's the potential to be signal checked for whatever reason even if they aren't calling.

[The SprinterMeister]

Could 2+9 or 2+10 climb Rattery Bank after a standing start from Totnes?  I know the 2+9s used on the Summer Newquay services do - but they are not booked to call at Totnes.

If 2+9 at least is cleared for the route then I'd assume (dangerous, I know!) they'd be fine starting from Totnes. After all there's the potential to be signal checked for whatever reason even if they aren't calling.

2+8 HST^▸ (High Speed Train)'s on one engine are not permitted to call at Totnes and must have a clear run from E96 signal (East of Totnes) to DM227 (top of Tigley bank). The weather / rail conditions must be conducive and no temporary or emergency speed restrictions must be in place. If the OEO^▸ (One Engine Only) 2+8 HST stop's in the section for whatever reason it is not permitted to attempt a restart on the steep rising gradient. All you will do is burn the traction motors out.

I will find out what the instructions are for 2+9 HST's over the Devon Banks. I have a feeling they are not permitted west of Newton Abbot on one enghine though.

[broadgage]

A 2+8 HST^▸ (High Speed Train) with both power cars running, but with one at reduced power output, seems to climb away from Totnes OK, so I would expect that a 2+9 would be fine with both engines at full power.

I remember one Christmas that a non standard* 2+9 set was on the 18-03, due to stop at Totnes, which it presumably did without incident.

As it appears that some HSTs are to remain in service for many years yet, I believe that serious consideration should be given to lengthening to 2+10.
Two power cars will easily move 10 coaches on level track at 125MPH, but acceleration and ascending inclines would be impaired.
This could be overcome by the fitting of a battery bank and traction motors in one coach, another 500HP would help considerably.
This tried on a prototype some years ago, and the idea sounds worth re-visiting.

*it had TWO coach "A"s, one at each end. So counting from the London end it was A,H,G,F,E,D,C,B,A. This was most perplexing for once a year travellers who thought that the coach A at the london end was the total for steerage, and not that five other vehicles were available.

[Southern Stag]

I will find out what the instructions are for 2+9 HST^▸ (High Speed Train)'s over the Devon Banks. I have a feeling they are not permitted west of Newton Abbot on one enghine though.

On the Western Region HSTs of more than 8 trailer vehicles on one engine only are not permitted unassisted:
Newton Abbot to Plymouth
Plymouth (Tavistock Jn allowed) to Newton Abbot
Paignton to Newton Abbot
Par to St Austell
Bromsgrove to Blackwell (Lickey Bank)
Llandeilo Junction to Cockett Tunnel (Llanelli to Swansea)
Fishguard Harbour to Clarbeston Road Junction

[Timmer]

I always thought that 2+9 was the max for an HST^▸ (High Speed Train) set though I guess if the MTU^▸ (Motor Traction Unit) engines are more powerful than the previous Valentas that might not apply anymore?

[broadgage]

I always thought that 2+9 was the max for an HST^▸ (High Speed Train) set though I guess if the MTU^▸ (Motor Traction Unit) engines are more powerful than the previous Valentas that might not apply anymore?

Not certain what the ultimate limit is.
It would depend on the route.
An HST on one engine will still eventually reach 125 on level track, so presumably a lot more than 9 can be handled with both engines working.

Whilst the new MTU engines have a greater potential output than the Valentas that they replaced, AFAIK^▸ (as far as I know) this does not help since the limiting factor is not the engine HP but the capacity of the main generator and traction motors that were retained.

[Gordon the Blue Engine]

I think perhaps that the key issue for an HST^▸ (High Speed Train) starting (or not losing speed) on a gradient on OEO^▸ (One Engine Only) is the weight of the power car.  Whatever the installed power (ie the diesel engine), and the transmission characteristics (ie max traction motor current, final drive gearing etc), the drawbar pull (or push) is limited by the weight of the power car and the adhesion limits you can expect.

The anti-wheelslip control on an HST power car is less sophisticated than on some modern 6-axle freight locomotives, and HST power cars are thus less able to maximise the adhesion available to translate into drawbar pull (or push).

[woody]

I seem to recall that when the East Coast mainline HST^▸ (High Speed Train) power cars were re-engineered at Brush shortly after the Great Western ones it was to a higher standard than Great Westerns power cars in that in addition to receiving new MTU^▸ (Motor Traction Unit) diesel engines they also received a larger brush radiator/cooler group together with all new control electronics with better anti-wheelslip control maybe something that could be incorporated into a future Great Western life extension along with possibly a higher rated MTU/traction alternator and traction motors combination to deal with 2+9 or 2+10 HST sets if it was cost effective.

[dog box]

partly right the ECML^▸ (East Coast Main Line) power cars did receive upgraded electronic and wheelslip equipment and FGW^▸ (First Great Western) have 2 of these powercars 43053 is one of them, although every Power car fitted with an MTU^▸ (Motor Traction Unit) Engine is fitted with a uprated VOITH Cooler Group as this is what mtu specified as being compatable with there engine

[The SprinterMeister]

I always thought that 2+9 was the max for an HST^▸ (High Speed Train) set though I guess if the MTU^▸ (Motor Traction Unit) engines are more powerful than the previous Valentas that might not apply anymore?

Not certain what the ultimate limit is.
It would depend on the route.
An HST on one engine will still eventually reach 125 on level track, so presumably a lot more than 9 can be handled with both engines working.

Whilst the new MTU engines have a greater potential output than the Valentas that they replaced, AFAIK^▸ (as far as I know) this does not help since the limiting factor is not the engine HP but the capacity of the main generator and traction motors that were retained.

The MTU engines are indeed limited by the power input of the alternator / rectifier / traction motors they are attached to. The 16V4000R41 is in essence a 1800 rpm engine derated to produce the same BMEP at 1500 rpm to give the required power output. Furthermore below 40 mph the traction system is power limited even further in order to keep traction motor currents at a reasonable value, the more current you put through the motors the more heat is created in the motors themselves. You aren't putting anything like 1775 rail HP down until you hit 40 mph, the actual rail hp diminshes with speed below that speed value. It does on all diesel electric locomotives but it is more noticeable with HST due to the higher mechanical axle gearing needed to achieve 125mph running without running the motors at ridiculous rpm figures.

43167-170 were trial fitted with Mirrlees MB190 engines set to 2400 flywheel bhp at 1500 rpm, a major rectifier fire caused the power output to be reduced back to the usual 2250 at 1500 rpm.

There are two other reasons why you may not run the MTU at 1800 rpm, one being the mechanical properites of the alternators themselves and the other being the three phase AC ETS^▸ (Electric Train Supply) / Auxilary systems which will not accept current at 60 hz / 1800 rpm due to the mechanical /electrical properties of the various motors and devices fed from the supply on both the power cars and the trailers.

[The SprinterMeister]

I seem to recall that when the East Coast mainline HST^▸ (High Speed Train) power cars were re-engineered at Brush shortly after the Great Western ones it was to a higher standard than Great Westerns power cars in that in addition to receiving new MTU^▸ (Motor Traction Unit) diesel engines they also received a larger brush radiator/cooler group together with all new control electronics with better anti-wheelslip control maybe something that could be incorporated into a future Great Western life extension along with possibly a higher rated MTU/traction alternator and traction motors combination to deal with 2+9 or 2+10 HST sets if it was cost effective.

You will not change the basic ability of the power cars to haul a given load over the banks merely by fitting a different wheelslip control system. You may in fact reduce it slightly as the Brush system (which is also fitted to FGW^▸ (First Great Western) 57/6) picks up more wheelslips than the basic 'current imbalance' one used on the FGW power cars. You will however reduce the tendency for out of control wheelslips / traction motor damage although if axle 3 on a GW^▸ (Great Western) power car slips up to 128 mph the traction power is removed from that power car anyway. The power you can transmit to rail is ultimately limited by the adhesive weight on the rails, the gearing / spcification of traction motors used and whether the traction unit is fitted with sand or not where poor rail conditions further limit adhesion.

[The SprinterMeister]

An HST^▸ (High Speed Train) on one engine will still eventually reach 125 on level track, so presumably a lot more than 9 can be handled with both engines working.

No it wont. 110 - 115 is as much as you will get and thats after about 25 miles or so.

[woody]

So franchise wise on the the Paddington/Penzance route it all seems to boil down to whether the next TOC^▸ (Train Operating Company) thinks its ok market wise to soldier on with a train whose performance remains largely frozen in a 1970s time warp or does it justify seriously uprating the HST^▸ (High Speed Train) power cars to improve their performance.Or do you go for say Meridians released by Midland main electrification or even more IEPs^▸ (Intercity Express Program / Project.).We will have to wait for the winning Great Western franchise bid for the answer to that one.Also given that the line speed profile is now the limiting factor here would it matter if train performance remains unchanged on FGWs^▸ (First Great Western) West of England main line.
   Given the transformation that is going to take place from 2017 with electrification and IEP on the rest of Great Western,performance wise the HSTs must start showing their age by then and there could be pathing  issues between Paddington and Reading on a then virtually all electric high density railway regards the slower accelerating HSTs say from signal checks.Of course ultimately its all down to cost and what the market/Government will bare of course.

[The SprinterMeister]

So franchise wise on the the Paddington/Penzance route it all seems to boil down to whether the next TOC^▸ (Train Operating Company) thinks its ok market wise to soldier on with a train whose performance remains largely frozen in a 1970s time warp or does it justify seriously uprating the HST^▸ (High Speed Train) power cars to improve their performance.Or do you go for say Meridians released by Midland main electrification or even more IEPs^▸ (Intercity Express Program / Project.).

Ultimately its all down to cost and what the market/Government will bare of course.

Of course if you go down the Meridian route (no matter how much you muck about with it a Meridian is still a Voyager in 'polished turd' format) your increased performance comes at a cost of more engines to maintain, less seating capacity per train and greatly increased fuel consumption. And more complaints about underfloor engine noise and worse luggage storage in all probability.

[IndustryInsider]

An HST^▸ (High Speed Train) on one engine will still eventually reach 125 on level track, so presumably a lot more than 9 can be handled with both engines working.

No it wont. 110 - 115 is as much as you will get and thats after about 25 miles or so.

I concur.  Also, it's worth saying that most of these operating rules are based on a worst case scenario, i.e. during leaf-fall, and what seems perfectly possible in fine weather soon changes when conditions are different.