Posted by: cjenscook | 08/16/2009

From Well to Wheel

There are few more contentious subjects in Edinburgh at the moment than the Edinburgh Tram. This project is currently running into massive problems as the streets are ripped up to to install the track creating a public and political outcry, and an accompanying commercial Mare’s Nest of contract over-runs.

Perhaps there might be a better way of approaching urban transport?

Rail and Road
In terms of energy use, the lower “rolling resistance” of steel wheels on rails compared to rubber tyres on roads, means that for given power output, rail is perhaps three times more efficient. Water transport is more efficient still, but this is only really relevant for certain types of bulk goods and commodities.

Urban transport evolved from horse drawn trams to the networks of electric trams or “street cars” which were commonplace in the first half of the 20th century alongside steam traction for inter-urban rail. Both in the US and the UK the coming of road transport saw a rapid shift to buses. The US saga of the destruction of the urban street-car network by Ford, General Motors etc is very much parallel to the way in which the UK rail barons destroyed their canal competition.

The standards of robustness of locomotives and vehicles which are applied to trains capable of high speed running between towns and cities are not appropriate for urban and suburban trams and light rail, but this fact has not really been addressed by policy-makers. The result is that vehicles are greatly over-engineered in terms of construction cost, and the resulting weight comes with an energy penalty over the vehicles’ lifetime.

Unfortunately, the Department for Transport is both stuck in the steam age – as adapted for high speed electric traction – on the one hand, and very much under the influence of the road/bus lobby on the other, of which more later.

Electric Traction
Proponents of sustainability – and I am one – who promote electrical traction often ignore the fact that the source of the electricity is for the most part, carbon based. In the almost complete absence of Combined Heat and Power (CHP) in the UK, electricity production is at best between 30 and 40% efficient. ie two thirds of energy goes up the chimney or into the river outlets. Add to that the transmission losses of electricity distribution to the vehicles, and “from Well to Wheel” the outcome in energy efficiency is pretty poor.

There is then the point that electric motors are pretty heavy pieces of kit, and when combined with over-engineered (but highly profitable) trams the result is vehicles which are so heavy that utilities have to be protected against the weight. The necessity of digging up the (imperfectly mapped) legacy of underground utilities accounts both for a large part of the cost of urban tramways, and also the huge disruption currently alienating most of Edinburgh’s population.

Finally, if we add to the energy losses the infrastructure costs of putting in place electricity cables or alternative conductors, then the result is that a modern tram network is pretty expensive. Once trams are in place, however, then, as in Nottingham, they appear to be very popular with users, and indeed attract many users who would not give up their cars for buses but will do so for trams or urban rail.

Ultra Light Rail
There are no more glorious eccentrics than British eccentrics, but it is often the case that today’s unconventionality or eccentricity may become tomorrow’s mainstream received wisdom.

Several pilot projects have been in operation in the UK for some time in the field of “Ultra Light Rail”, and it is fair to say that we probably have a lead in the field, as we once did in the field of wind turbines. These vehicles look like trams, but are typically self-powered using carbon-based forms of energy, and as the name implies, they are built to much lighter construction standards more typical of buses than of mainline trains or trams. New energy-saving developments – such as spinning flywheels – are also being tested and implemented.

There is no reason at all why fleets of such vehicles, probably powered by compressed natural gas, and with a view to running on BioGas (as with the Swedish bus fleet) should not be built and rapidly rolled out onto the streets of many British cities, and on re-opened suburban rail-lines,such as those in North Edinburgh.

Since the Department of Transport has historically been in the hands of the road lobby (although there are possibly signs that the ice is melting) we have seen such peculiarities as Guided Busways in Edinburgh and of course, Cambridge.

Here concrete guide paths have been largely laid on an old railway line between Cambridge and Huntingdon so that buses can drive along it. The cost for this initiative is £116m, and I suggest that taking Ultra Light Rail into Cambridge would have been both a better use of money, and a considerably more energy efficient route to sustainable transport.

The rising costs of the Edinburgh Tram project have already seen a couple of spur lines taken out, but my suggestion is that these could and should be reinstated. The tram network could then consist of a truncated core route using electrical traction, with the entire network being operated by ULR as well.

It will be seen that ULR is a complementary transport mode because ULR vehicles are just as happy on conventional rail as on tram lines. In other words, there is nothing to prevent ULR running on completed tram lines,and creating new routes where conventional trams are not viable financially.

A New Industry?
I believe that networks of ULR may be both rapidly rolled out (as they were a hundred years ago) at pretty minimal cost either in money or disruption, and offer a mechanism which could become one of the key elements of future cities with less automobile – centric suburban sprawl.

Certainly in Tehran – where the consequences of petrol at 20p per gallon have to be seen to be believed – and in many other energy rich nations like Nigeria, I believe that ULR offers a simple, fairly low-tech, and straightforward, key part of the transition from carbon-based fuels to renewable energy.

The UK can and should lead this process by doing what we are good at, and developing new generations of more advanced designs for domestic testing and use, which would then be licensed for production overseas.


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