Isn't the trolleybus old technology?
Internal combustion powered buses have been in common use in North America since the early 1900s. The trolleybus, by contrast, did not come into widespread use until the 1940s. Evolved out of motorbus and electric streetcar, it is most certainly the newer, and perhaps as some have insisted, "more civilized" form of urban bus transport. Just as better diesel buses have been developed over time, so, too, has the trolleybus been improved upon. New trolleybuses use sophisticated electronic equipment and brushless AC motors, saving on power consumption and reducing maintenance. New trolleybuses can move considerable distances without need for overhead wires thanks to Auxiliary Propulsion Units (APUs). In some designs, the poles can lowered and raised from the driver's compartment. Even the design of trolleybus overhead has evolved considerably. The modern trolleybus is a very sophisticated piece of machinery, indeed.
The use of rail-based streetcars predates both the diesel and the trolleybus. Essentially, it is streetcar technology that underlies today's light rail systems, yet few would consider LRT to represent 'old' technology. There is even less justification for applying the term 'old' to modern trolleybuses.
Is there a trend toward abandoning trolleybuses?
No. In fact, the opposite is true. Over the past two decades, more than twice as many new trolleybus systems have been opened than were abandoned. There are considerably more trolleybus systems operating in the world today than there were twenty years ago.
In the late 1950s and throughout the 1960s, many cities around the world did trade their trolleys for diesel buses, not because diesels provided better transportation, but because they believed they were either cheaper to operate or found them to be more readily available. North American systems that were suffering ridership losses due to suburbanization (urban sprawl) simply sought ways of reducing expenses and extending service to outlying areas at minimal capital cost. In those years, there were few alarms to signal that this would turn out to be a mistake environmentally. In the United States, producers of fossil fuels and manufacturers of diesel buses (who actually stood to gain more from the sale of cars than buses) undertook to monopolize the bus industry and supplant electric transport with internal combustion vehicles, ultimately putting trolleybus producers out of business. The environmental concerns and oil crises of the 1970s drew attention to the ecological value of electric bus transport, but, unfortunately, it was too late for those trolleybus systems that had already been dismantled or were on the verge of closure. By the mid-1970s, the trend toward abandonment stopped. Ever since, the number of trolleybus systems in the world has mostly been on the rise.
In the past two decades, rising concerns about pollution have generated considerable interest in the trolleybus. A number of world cities operating trolleys are expanding their systems. Examples include Linz and Salzburg, Austria; Guangzhou, Shanghai and Wu'han, China; Bergen, Norway; Dayton, Ohio. There have even been recent proposals in Great Britain and Hong Kong to build new trolleybus systems where none currently exist. In North America, Mexico City, Boston, San Francisco and Seattle are all currently renewing their trolley fleets; San Francisco has several route extensions on the books. Vancouver has plans to renew its large trolleybus fleet in the next few years. Most North American trolleybus cities have recognized that abandonment of this mode is a step backward given what we now know about the effects of exhaust emissions. In fact, the Chair of the Toronto Transit Commission recently issued a statement that the abandonment of the trolleybus system in that city had been a regrettable mistake. Winnipeg has twice put forth proposals to rebuild its trolley system since it was closed.
How do operational costs compare with other technologies?
North American cities operating both trolleys and internal combustion vehicles generally report slightly higher overall costs for trolleys. The additional expenses are incurred essentially as a result of maintaining the overhead wire network. Maximizing the use of trolleys helps keep the per unit costs associated with trolley operations down because the expense to maintain the overhead will be divided by more vehicles operating more revenue hours or more service kilometres. It is worthwhile pointing out that a good percentage of the expenditures associated with trolley operations benefit Edmonton workers and the local power industry rather than oil companies. City budgets have been big beneficiaries of EPCOR revenues in recent years.
Put in perspective, the additional operating expenses incurred by using trolleys in Edmonton tend to be insignificant with respect to the total cost of operating the transit system. Transit's biggest costs are staffing (operators and other personnel), administration, equipment maintenance and garaging. In Edmonton, the average additional operating expense of using trolleys vs. diesels over the past 10 years amounts only to around 0.1% of the total annual transit budget.
Of cities that operate multiple modes, many report that the highest operating costs are incurred with compressed natural gas (CNG) vehicles. This is largely a result of the fuelling infrastructure required and the increased maintenance needed on CNG vehicles.
As existing world oil reserves become depleted, the price of diesel fuel will rise irrespective of our plentiful oil sources in Alberta. Increases in the cost of diesel fuel have the potential to make the electric trolley more economical in the future despite of the added cost of maintaining the overhead network.
What is the cost of installing trolleybus overhead?
The trolleybus's forte is on heavily travelled "mainline" routes with stable ridership, fairly frequent service and frequent stops. Under these conditions the trolley's efficiencies and benefits are maximized. In North America, trolleybus infrastructure costs around $1 million per km of two way overhead. Compare this to surface light rail, which runs at around $17 to 35 million per km, and one realizes that trolleybus installations are relatively inexpensive for the benefits they offer. The high patronage on mainline routes ought to easily pay for the cost of the infrastructure.
In cities with trolleybus systems, the cost of adding new lines or building extensions is small when compared to the capital value of the entire system. In fact, maximizing the utility value of the system by extending the overhead, where practical, adds to the system's worth as a public asset and increases the environmental benefits associated with this technology.
Isn't the trolleybus 'inflexible'?
In heavily travelled corridors, the investment in trolley infrastructure provides route security, a feature that is attractive to riders. Transit experts agree that the so-called "flexibility in routing" associated with diesel buses can have a steep price in terms of maintaining and attracting ridership. Frequent route changes or detours tend to discourage riders. Such changes--easily possible with diesel service--can consume service hour allocations and extend travel times. As a result, transit trips that were once direct become convoluted, time-consuming and inefficient, prompting ridership losses.
When passage along a street is completely blocked due to an accident or other emergency and traffic is brought to a standstill, diesel and other internal combustion powered transit vehicles often fare little better at getting around the situation than the trolleybus. Movement away from the overhead power supply can be made possible on modern trolleys with devices called Auxilliary Propulsion Units (APUs). These may consist of a set of batteries that are kept charged by the overhead line current. In the event of inability to draw power from the overhead, the trolley can travel several km on battery power. This is enough to move the vehicle around obstructions, through de-energized sections, etc. Trolleybuses in Vancouver and in many European cities are equipped with APUs.
The term 'inflexibility' is often used in claiming that trolleybuses cannot be operated during road construction. However, the fact that many cities around the world maintain trolleybus operations through construction zones indicates this is not so. With appropriate and planning, the trolleybus can demonstrate considerable flexibility during road construction. Roadway improvement work on main thoroughfares typically proceeds only on one side of the street at a time. Traffic is still allowed passage by using the lanes on the side opposite to the construction. Where overhead design permits, the contact wires can easily be slid over on their spans to allow trolleys to continue operating on the usable side of the street. Where overhead must be removed to allow construction work to proceed and detours along adjacent wired streets cannot be arranged, APUs can power trolleys through a de-energized or unwired section. In the case of minor roadway maintenance work, much diesel substitution is really unnecessary. Adopting the attitude that transit vehicles should have priority on our streets would go a long way to keeping trolleys on the roads at times of construction.
Are trolleybuses faster or slower than diesel buses?
Typically, the trolleybus has much faster acceleration than the diesel bus, although diesel buses have improved considerably in recent years. Trolleys do have to slow down to enter "special work" (switches and crossovers) at intersections, but prudence would dictate that buses ought not to be speeding through intersections anyway. Compared with older diesels and even modern diesel articulated buses, trolleybuses can usually work faster schedules with the consequence that less vehicles ought to be required to perform the same work. Vancouver operators report difficulty maintaining their schedules when diesel buses are dispatched on trolley runs.
Speed of operation statistics for trolleybuses typically show them operating at slower average speeds than diesels, but this is only because trolleys are used on heavily travelled routes with frequent stops, whereas diesels tend to operate into suburban areas with lower traffic density and fewer stops. Thus a speed average taken for the entire diesel system will naturally be higher than one taken for the trolley system. Diesels running on trolley routes would not better the trolley's average speed.
Isn't the trolleybus more a vehicle for use in hilly terrain?
It is true that the trolleybus performs very well on hills. Hilly cities like San Francisco certainly appreciate the superior performance that electric transit can offer. But the majority of cities around the world in which the trolleybus operates have no hills of any significance, and many of the world's hilly cities have no trolleybuses. Environmental factors, public preferences and, in some parts of the world, low electricity prices, are more significant in defining the reasons why certain cities choose to operate trolleys.
How does the trolleybus fare in cold climates?
The City of Moscow, Russia operates over 1600 trolleybuses on some 90 routes. They have one of the severest winter climates among the world's trolleybus cities. The trolleybuses in Moscow are a highly reliable and revered form of public transportation. They have been nicknamed "soldiers of the streets".
In poor weather conditions, the carbon inserts in the trolley shoe need to be changed more frequently. Special 'sleet shoes' are installed in winter to remove ice from the lines, and these need to be changed out, requiring deployment of a service team. However, consider that the trolleybus needs no refueling, whereas staff are required to refuel diesel buses on a daily basis. Additionally, refuelling diesel buses exposes workers to toxic substances.
With all the cars on the road, bus emissions make up only a small percentage of the total pollution. Why bother to invest in cleaner bus technologies?
This argument is not logical. Each car also produces only a very minute percentage of the total pollution, in fact much less than a bus. The issue in considering whether to do something about transit's emissions does not revolve around the percentage of total pollutants produced by transit. Otherwise, one could easily 'clean up' transit vehicles simply by increasing the number of cars on the road, causing them to produce an even greater percentage of the pollution and thereby reducing the percentage originating from transit.
In a world dependent on transportation, cleaner air will only be realistically achieved by making manageable reductions wherever possible--by replacing traditional internal combustion technologies with cleaner alternatives and by maintaining and increasing our use of existing types of clean-air vehicles. Promoting transit on ecological grounds while ignoring the potential to reduce its environmental impacts with cleaner vehicle technologies is hypocritical, in particular when a sizeable investment in a cleaner technology like the trolleybus has already been made.
While successful transit schemes may have the ability to move people more efficiently than individual cars and reduce congestion, the emissions from the vehicles they employ are not necessarily in the best interests of our health and the environment. Data from the Centre for Science and the Environment suggests that a new diesel bus needs to have more than 25 car-driving passengers on board for its operation to constitute and environmental gain. The California Air Resources Board found that the emissions from one conventional diesel bus have the smog-forming potential of 65 passenger cars. Inhalation of diesel emissions at curbside, inside buildings and vehicles has been linked to cancer, asthma, respiratory disease and heart disease. In heavily travelled bus corridors in any city, transit's share of the emissions and resulting health impacts is significant. Attracting more people out of cars and into buses increases the environmental and health impact of transit, particularly in these corridors! Transit agencies that do not show initiative in optimizing the use of cleaner vehicles cannot credibly claim that commuters are contributing to a better environment by leaving their cars at home and patronizing their services instead. An automobile user will find no logic whatsoever in the argument that he/she should commit to using transit for environmental reasons if the transit system exhibits no visible environmental commitment itself.
Can the latest "clean diesel" technology using Ultra Low Sulphur Diesel fuel (ULSD) and Continuously Regenerating particulate Traps (CRT) compete with electric buses in terms of emissions impacts?
No. Vehicle emissions have their greatest impacts on those directly exposed, i.e. pedestrians, transit users, those living or working in busy transportation corridors. Trolleybuses produce no in-street emissions. Unless all the emissions diesels release into the surrounding air can be completely eliminated, the diesel can never be competitive with an electric trolleybus in terms of emissions impacts.
This should not imply that efforts to reduce diesel emissions are in vain. Diesel engines will continue to be used for a variety of purposes, and every effort should be made to make them as clean as possible. Reducing sulphur in the fuel, in and of itself, is a step in the right direction. But one needs to realize that making an internal combustion engine cleaner does not make it a universal substitute for an electric vehicle.
There are a number of factors to consider:
Greenhouse Gases: Currently available data from the British Freight Transport Association (FTA, 1999) indicates that the production of ULSD [at refineries] results in some 20 tonnes more CO2 equivalent than the production of regular diesel. Indications are that powering a vehicle with ULSD also requires more fuel than with regular diesel, meaning that, while some emissions may be reduced, the amount of CO2 released by the vehicle is likely greater. Based on available data, one would conclude that the use of ULSD does nothing to reduce the greenhouse gases responsible for global warming.
Particulate Size: Trap devices such as the CRT primarily focus on reducing the amount of particulate matter (the black material in diesel exhaust) by weight that is spewed into the surrounding air. There is also some concurrent reduction in hydrocarbon emissions. Some traps claim to reduce particulate emissions by up to 90% in tests, although their performance in real-world conditions may vary considerably. In any case, some particulate is still released, and that particulate is very minute in size. It is so small that it is invisible to the naked eye, but it quickly and easily penetrates the linings of the lungs. This fine particulate is believed responsible for an increase in lung disorders and asthma and has also been linked to cancer and heart disease. Indications are that managing this type of diesel pollution will require much more than just particulate traps. German researchers concluded that even the strictest Euro IV diesel emission standards are not tough enough.
NOx Emissions: In spite of trap devices, nitrogen oxides (NOx) still form a significant component of diesel exhaust and continue to pose health risks. Nitrogen oxides are transportation's principal contributor to urban smog and poor air quality. They comprise a mixture of nitric oxide (NO) and nitrogen dioxide (NO2). In combination with the moisture in the lungs, the nitric oxide (NO) component forms nitric acid. This acid results in inflammation, leading to respiratory illness.
Eventually, all nitric oxide emissions are converted to nitrogen dioxide (NO2) in the atmosphere. NO2 is a corrosive and very poisonous gas. At concentrations above 150 ppm it leads to death. The CRT (Continuously Regenerating Trap) uses a catalyst to convert nitric oxide in the exhaust stream to NO2 because it needs the NO2 for a reaction that 'burns off' particulate matter and hydrocarbons. There is a strong likelihood that the proportion of NO2 in the NOx emitted by CRT equipped engines operating in real world conditions will be greater than is the case with non-CRT equipped diesels. If so, it would put a greater quantity of the more poisonous constituent of NOx emissions directly into the airways of pedestrians, transit users, equipment maintenance personnel and operators than would be the case with conventional diesels, where the a slower process of oxidation in the atmosphere would be required to yield the same quantity of NO2. The possibility that ULSD in combination with the CRT might actually intensify some of the health effects of diesel exhaust needs to be subjected to thorough investigation.
Negative Environmental Repercussions: The environmental benefits of all exhaust after-treatment devices (like the CRT) was recently called into question when researchers discovered heavy metals from catalytic converters embedded in the ice in remote regions of Greenland. A European Commission study found that vehicle exhausts actually erode the metals in these devices, ejecting microscopic particles into the air. This effect is likely to be worse with diesel exhaust because of the corrosive effects of nitrogen oxides. Some of these heavy metals have been linked to asthma and lung conditions. Researchers noted that some of these particles are soluble, meaning that they can be readily absorbed by vegetation and enter the food chain. Researchers queried by New Scientist magazine concluded that this is already a problem is of global proportions.
Is the fuel cell bus a viable alternative to trolleybuses?
Although the fuel cell is known since the early 1800s, its practical application for motive power has been very slow to evolve. The feasibility and reliability of fuel cells in bus applications is yet unproven, although test vehicles have been built and tried. Weight has been a one major concern. Current fuel cell buses must carry so much heavy equipment that their passenger carrying capacity is about half of a 40 foot diesel or trolleybus. Range and reliability have been others. Tests in Vancouver showed that fuel cells were unsuitable for more than a few hours of service. Operational costs are currently very high--several times the cost of a diesel or trolleybus.
In order to utilize fuel cells to produce electricity, one requires large amounts of hydrogen. Hydrogen is not a naturally occurring commodity that can be tapped in the same manner as oil. Nor is there a distribution system in place like we currently have for petroleum fuels or electricity. The most readily available methods of producing hydrogen currently involve fossil fuels. During the production process, the greenhouse gas CO2 is produced in quantities that are not vastly different from what an internal combustion engine would generate. Thus, for the time being, fuel cell vehicles would not appear to hold great potential for greenhouse gas reduction. On the other hand, electric trolleybuses can be effectively made emission-free by purchasing wind energy, an idea already adopted by Calgary Transit for its LRT.
The energy efficiency of fuel cell vehicles is poor compared to other propulsion systems, and this is unlikely to improve significantly. The amount of energy required to produce, compress and transport 1kWh worth of hydrogen, then convert it to electricity in the fuel cell and use it to drive the wheels of the bus is tremendous. Ten trolleybuses could be operated from the energy it takes to run just one fuel cell bus.
While fuel cells may hold some promise for the more distant future, "direct electric traction" where power is supplied through overhead wires is still undoubtedly the most efficient and most reliable form of electric mass transit and is likely to remain so for some time.