Tuesday, October 23, 2012

Cars More Efficient than the Train ?


This was of course a bit of a wheeze of academia.

I wonder very much if Univ. Lancs wanted to attract some wonga from the car industry?

The ground breaking iMECHe paper is strangely not available on google now, probably because as a it did not stand up to scrutiny as a published academic work. In other words they seem to have got their sums wrong and not thought at all about the apples and the pairs, the swings and the roundabouts as we mere mortals love to laugh at : a lack of common sense and a lot of finding what you want to.

Firstly the measure is wrong actually, a completely wrong calculation in terms of benefit: the measure is fuel per seat per mile. It is apples and oranges- the car takes 8 to 10 hours, the 225km train half that, the 350  train would then be about 30% faster (with limited stops), 20% faster with the current stops. The actual calculation then which is the cost-benefit ratio is fuel per seat per hour: or just fuel by hour.

Example Table CO2 emissions 2011  which shows the IC 225 on its sub 5 hour journey being only slightly poorer than the 9 hour bus run. The plane is pretty awful compared to a Prius or a Polo blue motion, but is actually much better than anything Jeremy Clarkson would choose to drive in a traffic jam at 6.30 am to get to the beeb.

So train and plane get you there faster: the collective transport versus car comparison is then either bus or non super-express train ( ie 140 kmh). Then you have a like to like comparison, and in fact I find modern busses about as comfy as DMU/EMU trains and in fact given me as the driver can snooze, read, face book and even stretch legs at driver swaps. Buses weigh between 14 and 20 tonnes, and at an occupancy of even 50% than means they are taking more passenger per tonne of vehicle than cars. Bus fuel consumption varies. So does that of cars.

Averages for per mile were based on published mpg for the car, on a track at the most economic constant speed,  and in fact not an average based on constant, artificial speed, but was that a total consumption kwh for the trains as measured on the actual journey? So it is likely to be a theoretical car versus an actual consumption IC 225 train, or an average per real 100km in use on say the ECML (east cost main line) - the plane seems to be this too: ignoring the large amounts used on take off and landing and idle on say, Edinburgh - London: 15mins idle, 20mins climb, 10 minute descent, 10 minutes idle. The IC 225 and its replacement use small amounts while ideling at rest or deccelerating as mentioned below, less per the whole stock than supplying say the motorway service stations, over head lights and the airport air conditioning that are all part of the cars system.

The load factor is the next interesting qausi statistic: firstly you have to take the above into account: the car does not get 56mpg on the M1 at 85mph max and an average of about 60mph without stops, 45 with stops. With load 25% that is one passenger per 1.2 tonnes approx. At load 25% a 450 seat train has then 125 people which is then worse at 3 to 5 tonnes per passenger depending on train. However the train is then lighter and uses below average consumption. As loading goes up the car decreases fuel economy because the magical 56mpg is with 1.0 test driver with 0.0 luggage on a barmed track for 100 miles, or the metric equivalent. The train does not decrease in efficiency as much at 100% because relative to rolling resistance it increases its energy requirement less. The IC225 train has a peak of about 7000hp but continuous averaging about 2.4 kw / 3000hp. So that is the same hp per tonne per passenger as a car but comes from a source of energy which on the ECML is electricity and therefore open for increasingly renewable sources or CO2 bore well storage. Weight in a plane is far more prominent an issue in fuel consumption that pilots must calculate in to determine safe range, safe stacking time over destination, and when to refuel.

The train actually needs to be heavier per 25% loading which is  and the need in fact for  momemntun due to the way electrical gearing works ( the train must essentially roll on momentum to "change gear" it must roll through the slight pause of the electrical shift in volt/ amps) Also the train per tonne will coast very much further without making power and electric locomotives actually have had recirculant (rheostatic) electrical breaking where the motors act like generators and supply power to the system when decreasing speed.

Also the car occupancy is in fact 1.6 per car on average in the uk, in peak times, when most people want the benefit of fast, efficient travel. When public/ collective transport is over 100% per seat due to standing room.

So if you left London in peak time to make Edinburgh for dinner time in a car, even non stop, you would be leaving at rush hour or meeting a rush hour somewhere on the M1 or if you left later, you would meet Newcastle or Edinburgh rush hour.  Then your very ambitious, steady driving passat 56mpg can be forgotten. You go down and down as you sit keeping the motor warm in the rush hour. Trains are in fact little affected by the rush hour because their advertised, and actually very dependable timetable aka "diagrams" are fixed and there are procedures and sidings used in clearing conjestion which have evolved with the railway capacity at peak hours.

It is very frustrating when a train or signal or points fails. But on an express you can most often get up and buy a coffee. Outside the M6 RAC building north of Wolverhampton you will have had your coffee and be in need of a urologist by the time you reach spagetti junction.

Of course London to Edinburgh is some imperialist hangover of a yardstick: Manchester /NW to London SE is a more likely journey and as Jeremy Clarkson knows his v12 merc will be using gallons per mile as he even hits the RAC building at 0645. The 0710 train from Manchester glides out as you sit and look at the RAC building, and continue looking at it. I have sat outside its 1km vista and thought of the Irony that it lies before the motor cars worst. Or Bristol to London. Or anywhere to anywhere big which already has good collective transport solutions, and most of the key employment centres outside Slough, Swindon and Basingstoke, have excellent public transport links.

Both Jeremy Clarkson and "The Temporarily Smug blue motion Passat driver" with other half and two kids would be very pleased then that more people chose the train, because then they who choose the car get to destination, Edina -the shortbread tin capital- with less ques. But the passat driver in using 8 hours saves himself and family a lot over the price of intercity rail faires, capital costs of the car excluded.

No comments:

Post a Comment