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INFORMED SOURCES June 2004

Rail loses the environmental advantage

Nothing can equal the steel wheel on steel rail for environmentally friendly transport. Right? Not any more.

Looking back, the last time I wrote about energy consumption in transport was in April 1977 – before some of today's readers were born. And pretty erudite it was too.

One table showed the number of seats you could fit in trains at road coach seat-density, doing away with luxuries like toilets, buffets and luggage space. The answer for a 2+7 HST formation was 1,342.

‘Here we have a positive warning sign for when the energy crisis is upon us', I wrote ‘the sight of an HST arriving at Paddington after a highly energy efficient journey and 1,300 people alighting and making a bee-line for toilets and the buffet'.

So what happened next?. Well trains got less energy efficient, thanks to Health ‘n' Safety and the disability Taliban. Crumple zones and disabled toilets and regulations for running multiple units at over 100 mile/h mean that we now fit fewer, not more, passengers into trains which weigh more not less.

Progress?

Think I'm exaggerating? Look at Table 5 where a nine call all aluminium Pendolino weighs the same as a Class 87 + 10 Mk 3 coaches, with an increase in train mass per seat of 17%.

How's that for 27 years of railway engineering progress? The new 550 seat Airbus A380 with maximum fuel load ready ready to load will weigh less per seat than a Pendolino.

Table 5 West Coast train parameters 1977-2004

This retrospection was prompted by a paper to the Railway Division of the Institution of Mechanical Engineers by an engineer oft quoted in this column – Roger Kemp . Following influential roles at British Rail Research and GEC Alstom – where his team made Eurostar work, Roger is now Professor Kemp at Lancaster University .

His paper was on the environmental impact of high speed rail, but what caused some sharp intakes of breath were his intermodal energy comparisons of the latest cars trains and planes. Base line was the energy consumption per seat of a north of London Eurostar running on a notional high speed line between London and Edinburgh .

You have to allow for the losses in the train and the transmission system which together mean that the energy generated at the power station increases to 88 kWh. Next, modern power stations have an efficiency of around 40% and after converting kWh into the amount of oil needed to provide the same energy we get 22 litres of primary fuel per seat.

Table 6

Source R Kemp 2004

Now the primary purpose of the analysis summarised in Table 6 was to compare high speed lines with other modes and the surprise here is that a short haul airliner uses much the same amount of fuel to take a seat from A to B as a high speed train running at 350km/h.

But look at the modern diesel car, which has a similar consumption per seat as the conventional train. And compared to 125mile/h high speed trains the speed differential is not so marked on point-to-point journeys.

Table 7

Table 7 is the log of the outbound leg to a holiday cottage we were renting in Cornwall between Hayle and Helston.

Had we left home at around the same time, walked to the station and gone by train we would have arrived at Penzance Station (323 miles from WGC by rail) at the same time that the car pulled up outside the cottage.

And the Government is spending lots of money on roads so that highly efficient cars and lorries can cruise along with the minimum of braking and acceleration , which is what exacerbates energy consumption.

Load factor

Note that Table 6 assumes that all seats are occupied. I am beginning to have doubts about the validity of load factor adjustments in these discussions. On our trip to Cornwall we had a load factor of 50% throughout. The alternative IC125 out of Paddington would have seen the load factor start high and fall the further West it went.

Chart 1 summarises the effect of load factor on energy consumption per seat. This suggests, and I expect this will generate some howls of protest, that a family of four going by car is about environmentally friendly as you can get. Particularly as the car cuts out ‘dead' mileage to and from the airport or main line station.

More importantly, the chart demonstrates that high speed has an environmental cost. This is amplified in the graph of journey time versus energy consumption per seat.

So if we are really serious about the environment railways should be looking at lighter weight, higher seat densities and running more slowly.

Overweight

So where is the state of the art? Consider a four car Class 221 Voyager. Because it runs at over 100mile/h, HMRI rules bar passengers from the front third of the two driving vehicles. There are also seat-free crumple zones at the intermediate vehicle ends.

Then, some genius at Virgin thought three Classes were necessary. Thus, under the Rail Vehicle Accessibility Regulations the Voyager has three disabled toilets, each of which sterilises space for eight seats.

Finally, all the vehicles are total lardbutts, which is not noticed in performance terms because of the lusty, and very efficient, 750hp Cummins engine underneath. The net result is a train which has 186 seats and weighs 227 tonnes – a massive 1220kg per seat, or 40% heavier than a 2+8 IC125 at around 850 kg/seat.

As with so many aspects of energy policy it looks as if self delusion is the order of the day

Continues.........

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