Replacing DMU/EMU fixed formations - are we creating more problems in the future?

Hi Admin - please more if this isn't the correct forum.

Looking at the fixed formation DMU's and EMU's on Intercity services especially, is the rail industry wrong to focus on replacements such as 5 car IET's with projected population growth and potential increasing passenger numbers? Aren't we going to have overcrowding again in a few years?

This is probably particularly pertinent to TPE and X-Country.

Should we not be thinking of instead going Bi-mode Loco hauled with the new Mk5 carriages (like TPE are introducing), allowing for being able to add extra carriages in line with increasing demand?

The Mk5 sets on TPE are as long as the infrastructure currently allows, as far as I'm aware. They're also not a standard type of rolling stock like most LHCS trains used to be. Back in the day, operators could string together all sorts of different carriages and the sheer number of them across the network made it viable to produce them fairly constantly. With the new Mk5 and Mk5a carriages the likely only opportunity to extend them is when CAF is still interested in producing more of the same design, which is pretty much the same as for any EMU or DMU.

Technically speaking if it gets to a point of overcrowding, additional vehicles could be ordered. I know that hasn't happened much in the past, but anything can happen.

The fixed formation has been the norm since the HST era, although hauled stock was numbered in sets in Southern Railway days, so semi fixed formations is decades old.

Always been the case that a train will have excess capacity at certain parts of its journey or certain times of day. It may then form a working which is very busy so need the capacity.

What has been lost with fixed interval timetables is the old technique of timetabling a relief train 5-10 minutes earlier from a selection of busy stations to ease loadings on main train.

Responding to the specific query, on GWR there needs to be Swansea electrification and new 10 car (or 11 car if 290m platforms agreed) electric sets allowing the 5 car bi modes to replace those short HSTs. And in an ideal world I would also move the 4 car voyagers to routes like Portsmouth-Cardiff and get some longer trains for Cross Country. But I’m not rail minister so this would be a fantasy.

There is also a bit of a planning and purchasing problem (due to DfT franchise bidding stupidity) where taking options for additional vehicles in the event of growth seems to be discouraged.

Reliefs are compatible with a regular interval timetable, you just have to put them on top without changing the interval. VT have run one on a Friday evening for ages.

Snow1964 said:

What has been lost with fixed interval timetables is the old technique of timetabling a relief train 5-10 minutes earlier from a selection of busy stations to ease loadings on main train.

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Get these on the south end of the Snow Hill lines (however I think most run 5-10 mins after the main train rather than before.). Quite a few added in the May timetable and they work really well!

Bletchleyite said:

Reliefs are compatible with a regular interval timetable, you just have to put them on top without changing the interval. VT have run one on a Friday evening for ages.

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All that's doing is running the xx57 path for one extra hour on a Friday - i.e. where structural timetable space exists for it. And the crowding problem it was put there to solve was one created by the fares policy and peak/off-peak cut off.

You couldn't, for example timetable a relief train through the standard hour at Manchester Piccadilly or Birmingham New Street very easily.

NotATrainspott said:

The Mk5 sets on TPE are as long as the infrastructure currently allows, as far as I'm aware. They're also not a standard type of rolling stock like most LHCS trains used to be. Back in the day, operators could string together all sorts of different carriages and the sheer number of them across the network made it viable to produce them fairly constantly. With the new Mk5 and Mk5a carriages the likely only opportunity to extend them is when CAF is still interested in producing more of the same design, which is pretty much the same as for any EMU or DMU.

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The CAF Mk5a coaches are unpowered multiple units, effectively.

The CS Mk5s aren't, though (other than in software), which is a very odd thing. I'm surprised TPE didn't order them in a more standard way so they could be reformed to fewer longer sets later if appropriate. It could have been done with 2 types of vehicle - driving brake first open, then all the others as standard opens.

I think the screw coupling on the loco end mandated the reinforced end of that vehicle, but as the locos are dedicated why not fit a buckeye instead?

Snow1964 said:

And in an ideal world I would also move the 4 car voyagers to routes like Portsmouth-Cardiff

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Absolutely not. They would offer less capacity than the current (and future) rolling stock and not reflect the fact that this is a regional route that carries a high local load between the stations on the route.

Snow1964 said:

There is also a bit of a planning and purchasing problem (due to DfT franchise bidding stupidity) where taking options for additional vehicles in the event of growth seems to be discouraged.

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Very difficult because the payback period on additional vehicles is shorter than that of the original fleet. That makes lengthening existing rolling stock very expensive. Platform lengths often cause a problem as well.