Electric solutions for social problems
With the advent of bus rapid transport (BRT) upon us, FRANK BEETON suggests that the trolleybus is the natural way forward.
Two years ago, FOCUS on Bus and Coach speculated on the possibility of a comeback for the trolleybus, and we have carried the theme forward in more recent articles. The original article was sparked by news of an initiative in the United Kingdom to bring about the reintroduction of this vehicle type in the midlands city of Leeds. We pointed out, at the time, that, despite the demise of trolleybuses in their former British colonial strongholds, use of these pneumatically tyred, electric, passenger-carrying vehicles drawing current from overhead wires had continued uninterrupted in countries such as the United States, Canada, Poland, Russia, various Western European countries, China, Brazil and New Zealand.
Trolleybuses have always had their protagonists and detractors. Nobody can argue against their obvious virtues such as silence, good hill-climbing ability, lack of pollution and smooth operation, but the naysayers will always point out that, when the electricity supply goes down, all trolleybuses grind to a halt. In the days when these vehicles were required to operate in normal traffic, there was also the problem that trolleybuses drawing current from one set of wires could not overtake one another, so tended to run in “pods”, with everyone’s progress determined by the slowest vehicle in front. Other problems included traffic disruption from stationary vehicles when the trolleys “dewired”, and the safety risks associated with long stretches of exposed high-voltage electric circuitry. The demise of the British trolleybus was also hastened by the disappearance of cheap (usually municipal) electricity supplies after the end of World War II.
However, the present era – where environmental and energy-saving issues have become paramount, and public transport systems are making increasing use of alternative driveline technology – has the potential to bring the trolleybus back into play. The bus rapid transit (BRT) scenario, which is gaining increasing favour as a congestion-solving, lower-cost alternative to light rail in urban and suburban environments, provides a segregated right-of-way with controlled public access and no competing traffic, which could be seen as a favourable operating scenario for trolleybuses. The widespread adoption of hybrid and fuel-cell buses has also introduced a new generation of electric traction technology, which would be equally at home in an all-electric vehicle, whether powered by a battery, an outside power source, or a combination of both. Both of these alternative scenarios have also conditioned operators to accept “different” vehicles, because the risk of running new and relatively untried technology on fixed routes, relatively close to maintenance infrastructure, is considerably reduced when compared to the free-for-all of unrestricted operation.
The trolleybus offers all the benefits of the other environmentally friendly technologies without the complication of the on-board internal combustion engine, multiple transmission functionality and batteries associated with the hybrid equation, or the questionable safety of a fuel-cell vehicle carrying volumes of liquid hydrogen fuel. Once the (initially expensive) supporting overhead catenary infrastructure has been put in place, the operator is positioned to offer a relatively simple, clean, quiet, non-polluting service, even if he chooses to retain the battery option in order to provide some measure of power-down emergency mobility.
If there is any widespread reawakening of interest in trolleybuses in those areas where they previously fell from favour, it will be very interesting to see which manufacturers emerge to exploit the potential business. The trolleybuses operating in Europe and North America tend to be modified versions of mainstream motor bus designs, which suggests that their technical layouts may be far from optimal. However, with the increasing global interest in hybrid and fuel-cell buses, new thinking is increasingly evident in the bus-making arena, and this means that even the traditional makers of motor buses have been taking a fresh look at how they configure electric vehicles. The main advantage of the trolleybus is that it potentially dispenses with the need to provide space for items like engines, transmissions, generators and battery packs, making more space available for passengers. The historical use of large underfloor traction motors, driving conventional axles by way of propeller shafts and differentials, has also been made completely redundant by the adoption of smaller electric motors mounted at the axles, driving the road wheels directly. This development removes the need for “live” axles, allowing the adoption of independent suspension layouts, and freeing up additional space for completely flat floors.
Since the demise of the Soviet Union and the dismantling of the Iron Curtain, vehicle manufacturers from the former Soviet bloc have been taking tentative steps to enter a broader world market. Given that these countries were substantial trolleybus users, it follows that well-established bus builders were numbered among the industries that were now adopting a more outward approach. One such firm is Belkommunmash (BKM), which was founded as the Tram and Trolleybus Overhaul Plant in Minsk in 1973. This Belarus trolleybus and tram manufacturer has appointed ONS Industry of Hamburg, Germany, as its sole distributor outside of its home country, Russia and the former CIS States. At the UITP Expo 2009 held in Vienna in June, the company exhibited its newly introduced model 42003A trolleybus, which has already attracted an impressive total of 780 unit orders in 2009.
The bus is 11.8 m long and 2.5 m wide, with 29 seats and total accommodation provided for 100 people in the standard version. The design features a flat floor, and has two door apertures with the forward door situated behind the front axle, and a self-contained driver’s cab. Traction is provided by a Skoda ML3550 electric motor rated at 185 kW and 1 200 Nm, and the air-suspended axles are sourced from ZF or Raba (the latter is an alternative source for the rear drive axle only). The service brakes are dual-profile drum units with ABS, and secondary braking is available from the traction motor. Optional equipment includes a battery to enable a
6-km range independent of the overhead power supply, or the vehicle can be configured as a hybrid, when it is also equipped with a 120-kW Steyr diesel engine and Jenoptik generator, to further extend its “disconnected” range potential.