Maintenance costs for trolleybuses remain fairly stable over the period of service, whereas for conventional buses these rise after the first 10 years. In order to develop the market, manufacturers would have to reduce the weight, the bulk and the price of their components. The fixed installation components also needed rationalisation. Dual-mode trolleybuses offer the possibility of saving on the costs of system installation, via their capability of switching to conventional fuel where this is more convenient. Installation of trolleybuses is substantially cheaper than that of metro systems, and it offers the option of extension as passenger demand expands.
Trolleybuses are ideal for serving areas where quiet or non-polluting vehicles are required.
Background Various European countries had been examining the reintroduction of electric-powered urban public transport. Light rail, modern tramway, electric conventional buses and trolleybuses are attracting interest with the growth of environmental concern about urban centres. Between 1975 and 1985, more than ten dual-mode trolleybus prototypes have been developed in Europe. It was therefore seen as valuable to make a comparison of these and to research further the optimum direction for these versatile vehicles in urban public transport systems.