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INFORMED SOURCES July 2006

New trains getting heavier

Hauling surplus weight around imposes extra costs – financial and environmental

Back in June 2004 (on-line archive Alycidon Rail at www.alycidon.com) this column made itself unpopular by pointing out that rail was in danger of losing its green credentials. This had been inspired by a typically provocative paper by my old chum Prof Roger Kemp of Lancaster University

What upset people was the claim – backed up with the usual tabular overkill from the two Rogers – that cars and aircraft were becoming more energy efficient while trains were getting less efficient. Various reasons for this situation were adduced, not least the impact of sundry well meaning legal requirements on the number of seats in each vehicle. There was also the tendency of post-privatisation vehicles to obesity – reflecting their continental heritage.

Interestingly, or perhaps depressingly, ministers at the Department of Transport embraced what some saw as the Kemp-Ford heresy and used it to beat railway managers over the head. Now-shuffled-off Transport Secretary Alistair Darling picked up the theme at a conference in March.

On the popular view of rail as one of the greener ways to travel, Mr Darling commented, ‘it is, but only up to a point'. Looking 20-30 years ahead, ‘the picture is not as straightforward', he said.

According to the Transport Secretary, 20 cars today produce fewer emissions than one car built in the 1980's. This is, typically, misleading, since it excludes CO2.

Anyway, in comparison ‘rail has not done as well as it could'. Acknowledging, a trifle optimistically, that the MTU diesel enngines in the re-engined IC125 power cars would give an ‘18-20% reduction in fuel use', he warned tnat elsewhere ‘the picture isn't so good'.

In particular he pointed to the increasing weight of European rolling stock. The Transport Secretary equated the weight per seat of a Class 390 Pendolino to ‘half a Landrover Discovery', which causes ‘a lot of wear and tear on the track'. He contrasted this with Japanese trains, which are down to under 500kg per passenger and falling.

Sumo imports

Well, in Japan , yes. But not for export.

A four car Bombardier Class 357 Electrostar weighs 560kg/seat. The six car Hitachi electric multiple units for Channel Tunnel Rail Link Domestic Services will be a third heavier at 740kg/seat.

In some ways this comparison flatters the incomer because the Class 357 spreads the extra weight and dead space of two cabs across four vhicles versus the Japanese train's six. On the other hand, the Hitachi will include first class seating and will probably lose space to higher-than-necessary crashworthiness requirements

I will return to Japanese experience later. But what set off this piece was the weight of the latest trains from the Siemens, the Desiro class 185 DMUs for Trans Pennine Express.

Table 1 DMU vehicle weights

Notes:

* Cummins QSK 19 engine rated at 750hp

1) No air conditioning

2)Average weights.

3) 9-car Meridians only

DMU history

Table 1 lists the modern 23m long DMU vehicles in service today. The first thing to note is that, in retrospect, the air conditioned Class 158, at the time Regional Railways top of the range DMU, was a weight conscious piece of design.

Note, next, the difference in weight between the Class 165 and Class 166 which suggests that in the early 1990s, air conditioning added around 2tonnes per vehicle.

After 1074 days without an order, during which the train builders refined their designs for the new privatised railway, Adrian Shooter ordered the first new DMUs for Chiltern. This was the Class 168 Turbostar which launched the Class 170 dynasty.

Note that compared with the Classes 158 and 166, the Class 170 takes the weight of an air conditioned DMU vehicle to over 40 tonnes. I should add, here, that because the basic Class 168/Class 170 design comes in so many different flavours, Bombardier has given me the average vehicle weights.

If you think the Class 170 is a bit portly, then look at the steel bodied Class 175. Washwood Heath was never into light weight; compare, for example, the neo-brutalist Mk4 body shell with the structural elegance of the much older Mk 3 which is both lighter, yet stiffer, stiffness being one contribution to that magic carpet ride. However, even with air conditioning, 10 tonnes heavier than the Class 156 is some achievement.

Muscle

All the vehicles mentioned so far are powered by either the Cummins 14 litre, Perkins 12 litre or, in the case of the Class 170, the MTU 11 litre, engines. Now we come to Captain Deltic's favourite muscle trains, with the 750hp 19 litre Cummins QSK19 engine shoe-horned into the underfloor raft. And there is more than just the weight of the larger engine to consider.

More power at the flywheel means more waste heat to dissipate which equals a bigger and heavier cooler group. More power equals more fuel, which means bigger tanks. Plus, running at 125mile/h requires cab-ends with additional energy absorption to meet crashworthiness requirements.

We can see the difference in the Alstom Class 180, which is 4-5tonnes heavier per vehicle than its lower powered, slower sibling. The table also confirms that when it comes to building efficient steel body shells, my Bombardier chums in Brugge have better CAD programmes than Alstom at Washwood Heath.

But then we have der Dicke. Every Siemens Class 185 vehicle is over 50 tonnes and the driving vehicles are around 4 tonnes heavier than the Class 222. If you create a notional three car Class 222, using the heavier of the two Motor Seconds, the Siemens design is hauling around an extra, and unnecessary, 14.63 tonnes – and I have used the painted weights on the vehicle ends.

Costly complacency

But that's not all. In the bidding for the TPE order, Bombardier were offering a high performance Turbostar (Informed Sources April 2003). Table 2 shows the difference.

Three car DMU weights (tonnes) and variable track access charges (all 2004-05 prices except Class 185 2005-06

At the opening of the Ardwick Depot, my colleague Tony Miles raised the issue of the overweight DMUs with both TPE and Siemens. TPE said ‘we have not been advised of anything. The trains have received their VAB approval and the issue of their weight has not been raised as an issue by Network Rail. The sets are currently running at the prevailing line speeds'. Siemens explained that, unlike the products from other train manufacturers, the Class 185s were built to last.

Hmmm. This complacency shows why rail is losing its environmental advantage. And First Group seems to have lost its commercial marbles.

I calculate that, compared with a Turbostar, a Class 185 uses an extra 1.8 litres of diesel fuel to get to 100mile/h. Even against a Class 222, the difference is a litre. If the comparison with a Class 158 got into Government hands it could be the end of railways as we know them, but you can e-mail me.

With the high price of oil this difference has to hurt the train operators' bottom line. It will also hurt the environment since a litre of diesel produces 2.63kg of CO(subscript)2.

And the track does suffer, as reflected in the variable usage component of an operator's track access charges. A Class 158 pays 11.26 pence/mile per vehicle (2004-05 prices) while a Class 170 pays 14.19 p/mile.

When we get onto the heavy metal, a Class 220 Voyager pays 20.61p/mile, a Class 180, with French bogies, comes in at 24.52 p/mile and a Class 222 21.46 p/mile. Since track dynamics are speed related the 100 mile/h Class 185 costs 19.13p/mile per vehicle, although this may be revised.

Assuming eight million unit miles per year for the TPE fleet, then where Class 158 operation cost £2.7million a year in variable TAC, the Class 18s will be around £4.6million a year. So that's another £1.9million of the taxpayers money being going to waste.

Track

As for Network Rail being happy, here is a quote from the company's 2006 Business Plan:

‘Network Rail are working with Transpennine Express to find ways to allow the Class 185s to operate at some of the previously sprinter only speeds on the Hope Valley route. If this is not possible the higher acceleration of these units on other sections of the route should help to offset the affect of running at the non sprinter speeds'.

Let's just run through this last sentence again. The track forces are too high to allow operation at the enhanced speeds permitted for Class 158s but, hopefully, by unleasing more horsepower (and CO2) to accelerate surplus weight faster everything should be just fine.

Lightness

Now back to the Japanese experience. An article in the May 2006 issue of Railway Gazette International gives the weights of the latest JR East Tokyo suburban EMUs. A 10 car Type 209.500 set, formed with 20m long vehicles including four motor cars. weighs just 255 tonnes and provides 518 seats.

Comparing the Type 209 with the preceding Class 205 of 1985 vintage, the weight of a motored car has fallen from 32.61tonnes to 27.7tonnes. Now compare those numbers with the weights in Table 3.

Table 3 EMU train weights

All weights in tonnes

*No air conditioning

One point must be made. As anyone who has travelled in a Desiro knows, the ride is superb. This is partly a function of the ratio of sprung to unsprung mass, with a heavy vehicle giving a better ride. And the trim is unmatched when subjected to the fist of quality – so the weight is partly my fault.

Meanwhile, what's to be done? New Rail, the Centre for Railway Research at the University of Newcastle upon Tyne , is currently looking at materials substitution to save weight and provides a classic example of the corporate knowledge that was lost with British Rail Research.

In the Railway Gazette article quoted, New Rail Director Prof Mark Robinson and his Japanese co-Author comment, ‘We might reasonably ask why there has not been a greater use of lightweight materials such as composites in European rail vehicles. JR East uses composite for interior panels to cut manufacturing costs'. They concede that there may be … barriers preventing the introduction of lightweight materials in some areas, for example fire performance.

Switching to weary old fart mode, New Rail's first task should be some intensive desk research into what Old Rail knew. A starting point might be the papers from the 1987 IMechE seminar on ‘Materials for rolling stock'. Killing two birds with one example, British Rail Engineering had developed production techniques for composite components, ranging from cab ends to interior panels, using phenolic resins to meet fire regulations.

But while every little helps, reversing the weight gain is down to the structural engineers and a willingness to trade off manufacturing cost against whole life cost. That 1987 conference included a paper on prototype aluminium freight bogies and MBB of Germany described a composite 250km/h passenger bogie aimed, among other things, at reducing weight. And shouldn't we take another look at stainless steel?

But we also need to ask who has the incentive to mount a serious attack on train weights in the UK ? Not the ROSCOs, not the TOCs, not DfT Rail – all of whom want to buy cheap proven products off the shelf.

However, one organisation would benefit financially from lighter more track-friendly rolling stock and that is Network Rail. And with their government-backed loan facilities, they might even fund as well a specify and procure.

Continues.........