A clean, green, electric machine that's an alternative to trams

Published on Tuesday 12 June 2007 00:10

THE "Don't Trash Our Trams" campaign in Edinburgh is right to say that a "reliable, integrated transport system is vital for the economic prosperity of the city". But there is a tried-and-tested alternative to trams that has been neglected so far in the debate - modern trolleybuses.

For those too young to remember them (the last one ran in Glasgow in 1967), trolleybuses are vehicles with rubber tyres that are powered by electricity obtained via "trolley poles" from overhead wires.

In the UK they replaced the first generation of trams because of their greater flexibility and lower maintenance costs, but the short-term economics of renewing trolleybus systems during a period of low oil prices convinced UK operators to switch to diesel buses instead.

Using battery power or an alternative fuel source such as diesel or biofuel, modern trolleybuses can run for short distances without the wires, for example if there are diversions from the wired routes in the historic centres of cities such as Rome and Beijing.

Like trams, modern trolleybuses, are a green technology, emitting no pollutants at street level. They run so quietly that the Glaswegians mistakenly called them the "Silent Death" because of the perceived likelihood of getting knocked down. In fact, the safety statistics of trolleybuses are every bit as good as for diesel buses because of powerful brakes and the friction afforded by rubber tyres.

A key difference between trolleybuses and trams is the cost. Because a trolleybus system doesn't require tracks and the diversion of utilities, the cost of installation could be up to 50 per cent less. The electrical equipment in trolleybuses and trams is inherently longer-lived and cheaper to maintain than the diesel engine and its associated noise and emissions control systems.

If trolleybuses are so good, why were they not considered for Edinburgh? It is possible they were not thought "good enough" for a capital city - the only capital in western Europe without a tram system from Luxembourg, Cyprus and Malta.

Other alternatives mentioned in the transport debate include hybrid buses. Unfortunately the technology is still relatively new and hydrogen powered vehicles are impracticable because of their low efficiency and high weight.

A key argument against dropping the tram scheme is the amount of money that would be wasted. However, trams and trolleybuses use similar infrastructure, so if the tram scheme fails, a lot of the work done by TIE could be equally applicable to a system of "trams on tyres".

For the sake of the environment, human health and economic development it is important that we create an electric transit network in Edinburgh.

It might in the long term be possible to electrify many of Edinburgh's bus routes. And why stop in Edinburgh? If the Dutch city of Arnhem (population 142,636) can have a trolleybus network, why not Dundee (population 143,090)?

• David Sterratt is affiliated to the Electric Tbus study group promoting electric transit in Scotland.