Modern Trolley Buses

A trolleybus is generally a standard motor bus with poles, electric controls and motors in place of an internal combustion engine and associated systems. It relies on an external source of power – two overhead wires which the poles contact (for more information see the article on electric vehicle technologies).

Vancouver operates a large fleet of trolleybuses. All 244 buses were built in 1982 and 1983. BC Transit currently plans to not buy any trolleybuses at least until the year 2003. Transport Action BC advocates not just retaining but expanding the existing trolleybus system, and would like in the short term to see BC Transit buy articulated trolleybuses to improve service and reduce crowding on existing, heavily used routes.

Issues – trolleybus versus motor bus

The major advantages of trolleybuses over buses powered by internal combustion engines are:

  • no direct emissions
  • more energy efficient
  • quieter
  • better acceleration
  • less maintenance intensive (less brake wear, motors last longer and do not require overhaul every 5 years)
  • longer lasting

The major disadvantage is the requirement to run under wires. The cost of installing the wires, support structures and electric substations is a significant sunk cost which needs to be justified. In addition, trolleybuses are significantly more expensive to buy than diesel buses, presumably due mostly to the relative market size for the two types of bus. Note, however, that trolleybuses are expected to last longer – in Vancouver the trolleybuses are expected to last 30 years, whereas diesel buses are expected to last 20 years.

Another disadvantage of trolleybuses is the requirement to pass slowly under switches. However, switches are most often at intersections where buses need to make a stop anyway.

Other differences are not clearly advantages or disadvantages. Some people think overhead wires are unsightly. Others are not bothered by them and some view them as a visible investment in public transit. Some people consider the inability of trolleybuses to pass each other a disadvantage. Others prefer that buses not be able to play leapfrog.

Latest developments

The most significant recent advance in technology is the use of brushless AC motors, which require less maintenance than DC motors. This has been made possible by advances in solid state electronics.

The low floor bus has become very popular as well, for the same reasons as for low floor light rail vehicles.

Dual mode buses are being used in many locations to allow service to areas without overhead wires but still provide quiet, electrically powered service on the busiest part of the route. These buses include both a diesel engine and electric (traction) motors. In some designs the diesel engine is used as an electrical generator, in others the electric motor powers one axle (of a 3 axle articulated bus) and the diesel powers the other. Seattle has a fleet of 236 of the latter type – these are generally used in electric mode through the downtown tunnel only.

Click here to see the electric trolleybus manufacturers and orders.

What’s out there today?

The following lists some articulated trolleybuses the author has information on. This list is far from complete and at present lists mostly dual mode buses.

Each description includes the manufacturer, city or cities in which the bus is used, the date the bus type was first delivered, the total number in service or on order, floor height(s), the bus’ length, width and mass, the number of motors and total power, and the number of seats and total capacity including standees (as claimed by manufacturer – I don’t think this is the standard 4 standees per square metre, so take it with a grain of salt).

Low floor

MAN, Kiepe
Innsbruck, 1989, ?
floor height ? mm
17.4 m x 2.5 m
15 tonnes
1 traction motor (149 kW) driving 3rd axle, 1 diesel engine used as generator (49.8 kW)
Seats 47, total 142

NAW, Hess, ABB
?, 1991, 1 (prototype)
320 mm (front door), 340 mm (second door), 575 mm (back door)
17.77 m x 2.5 m
17.4 tonnes
2 traction motors (89 kW each), 1 diesel engine used as generator
Seats 40, total 143

Van Hool AG300T
17.93 m x 2.49 m
16.8 tonnes
1 traction motor (150 kW), 1 diesel engine used as generator (150 kW)
Seats 42, total 146

High floor

Volvo, ABB
Fribourg, 1988, 12
745 mm (front and second door), 825 mm (third and back door)
17.68 m x 2.5 m
17.9 tonnes
1 traction motor (152 kW) driving 3rd axle, 1 diesel engine driving 2nd axle
Seats 35, total 140

NAW, Hess, ABB
Schaffhausen, 1991, 8
606 mm (front door), 761 mm second and back doors
17.85 m x 2.5 m
17.4 tonnes
2 traction motors (89 kW each), 1 diesel engine used as generator
Seats 42, total 149

Daimler-Benz, ABB
Zürich, 1988, 36
710 mm
17.4 m x 2.5 m
16.4 tonnes
1 traction motor (152 kW) driving 3rd axle, 1 diesel engine driving 2nd axle for emergency operation
Seats 50, total 166

James Strickland