In the consultation document, "FROM WORKHORSE TO THOROUGHBRED A better role for bus travel", no direct attention e.g. a section of its own, is given [although there is indirect attention e.g. in 1.1, 2.2, 3.2, 4.1, 4.6, 5.2 and 10.9], to the opportunity to achieve substantial improvement to the local environment of our urban streets and to the environment in general, by encouraging more environmentally friendly bus propulsion systems.

In particular, no attention is given to the opportunity to encourage electric buses.

The environmental advantages of electric vehicles are, or should be, well known, but are worth summarising:-

1. Zero emissions in the streets
2. Lowest possible noise levels
3. Lowest possible emissions into the environment as a whole
4. Lowest possible consumption of non renewable resources
5. Lowest possible release of ‘green house’ gases like CO2

Advantages 1 and 2 are, hopefully, obvious, and well worth having in their own right.

Advantages 3, 4 and 5 are linked and are due to the simple fact that a small number of large stationary energy converters [power stations] offer the following environmental advantages over a large number of small mobile energy converters [internal combustion engines]:-

1. Much higher conversation efficiencies - hence less fuel consumption and less CO2 production - in large fixed plant operating under stable conditions than small mobile plants operating under continually varying conditions
2. Ability to control emissions like CO, NOx, SOx, HCs or particulates, more readily in large fixed plant operating under stable conditions than small mobile plants operating under continually varying conditions
3. Ability to use energy resources that are impractical or impossible in vehicles e.g. like wind and water power or solid fuels

Clearly, when and if, development in storage battery technology, produces batteries that can compete in terms of size, weight, cost, ease of recharging, etc., with say, a tank for diesel fuel, all vehicles could be electric, with all the environmental advantages that would bring.

However, this is very unlikely to happen in the foreseeable future and the only generally practicable system for getting electric power to moving vehicles is via an energy conductor system.

Where vehicles operate a fixed route at sufficient frequency, it is both practicable and economic to provide an energy conductor system. Thus in many railway, and virtually all light systems, electric propulsion via an energy conductor - conductor rail or trolley wire - is the norm.

The same could and should be true for many of the intensive / guided bus routes envisaged in the consultation document.

Thus there would seem to be a very good case, in environmental terms, for actively encouraging the re-establishment of trolleybus systems in the UK. Since the last trolleybuses ran in public service in Britain in 1972, there have been many advances in the technology of trolleybuses, both in the vehicle technology e.g. the introduction of AC instead of DC propulsion systems and in the power supply systems e.g. solid state instead of mercury arc substations and improvements in the design of the overhead wire systems.

To give some figures, courtesy of Kevin Brown of the University of Alberta, based on Canadian [Edmonton] experience, comparative emissions for the latest technology diesel and trolleybuses [expressed in grams of pollutant emitted per vehicle kilometre driven] are:

Diesel bus Trolleybus

CO2 1657 891

CO 4.3 0.06

NOx 13 1.98

SO2 0.2 Nil

Particulates .7 Nil

HCs 1.5 Nil

In environmental terms, the trolleybus is clearly the cleanest vehicle going. Obviously this advantage can only be achieved if bus routes are wired up and this wiring has a cost, which has to be paid. However, on reasonably intensive routes, the full costs of providing the overhead wiring, should be able to be recouped from savings in the much lower maintenance costs of electric trolley vehicles compared with internal combustion engined vehicles - reference West Yorkshire PTE "Alternative Tractions Options Project" report 1980.

A current problem is the price of new trolley vehicles. When trolleybuses were in regular production in the UK in the past, a trolleybus cost about the same as a diesel bus. With the limited number of trolleybuses now being produced within the EU, the best price currently for a new trolleybus [e.g. for Athens], seems to be around double that of an equivalent diesel bus.

Initially, encouraging trolleybuses, would probably involve some additional funding from passengers, taxpayers, etc., compared with diesel buses. However, if the trolleybus were to be actively encouraged [in the UK] and a regular market for new trolleybuses built up, there is no reason why new trolleybuses should not compare in price with diesel buses. In such a situation, all the environmental advantages of trolleybuses could be obtained without passengers, taxpayers, etc., having to fund them as such [compared with diesel buses]. Indeed, trolleybuses may well cost less!

As well as some initial additional funding, encouraging the development of trolleybuses in the UK will require attention to the removal of barriers or disincentives to the establishment of new trolleybus routes. In particular, the climate of UK bus regulation since 1986 has not been favourable to trolleybuses, and approval procedures for new trolleybus routes - which seem to be geared more to light rail requirements - are unduly onerous and expensive compared with those for motor bus routes.

Eur Ing Irvine Bell BSc CEng MIMechE CDipAF PGCE

June 1999.