Sunday, July 27, 2008

Effective Speed

Which is faster? We all know that in the city you can get around much quicker on a bike. But is your car eating up more time than you think? How many extra hours are you spending at work in order to pay for it?

Is it worth investing hundreds of hours per year to pay for a mode of transport that might save you only half of that in travel time? This report by Paul J. Tranter from the School of Physical, Environmental and Mathematical Sciences in Canberra was prepared for the Australian Greenhouse Office, part of the Federal Department of the Environment and Heritage. The report considers the concept of ‘effective speed’, where speed is calculated on the basis of the total amount of time consumed by a particular mode of transport. Applying this concept of ‘effective speed’ provides some surprising results in the comparison of cars and bicycles.

Cars are more expensive than we believe they are. Many car drivers base their estimates of the
costs of driving on the amount they pay for fuel ‘at the pump’. Yet fuel accounts for only about 20% of direct car operating costs in Australia (NRMA, 2004). Motorists tend to ignore (or
underestimate) the other direct costs that they themselves pay to keep their car running (RACV, 2004), and very few drivers consider the external costs of car ownership (the costs that are not paid directly by them, but which are borne by society). A study by the RAC (Royal Automobile Club) in the UK found that drivers grossly undervalue the costs of motoring, estimating their expenditure at a level of less than 40% of the real average cost.

Perhaps the most pervasive belief about cars is that they give us the advantage of high speed. The promise of high speed is used to sell motor vehicles throughout the world. In Australia, many car companies use speed (or the suggestion of speed), along with clear links to motorsport, to sell theirhigh performance cars (and the rest of their models as well). Honda uses Formula One sounds and cars in its advertisements. Mitsubishi has used rally racing to help sell its Magnas. Ford and Holden have used success in V8 Supercar motor racing events to sell their Falcons and Commodores. Even Daihatsu has used car racing footage in its advertisements for its tiny Sirion! “automakers are selling speed because they know that speed sells” (Healey, 2004).
Despite the advertising hype, average driving speeds (trip speeds) are remarkably low in most
cities, particularly in inner city areas where traffic speeds are not much higher than walking speeds. Even if you could travel at high speed in your car the advantage over other modes of transport is questionable when the total time devoted to the car is considered. The ‘effective speed’ of the car is limited by the time investment needed to keep cars mobile.

Effective speed can be calculated using the formula:
“Speed = distance divided by time”, where
• distance is the total kilometres travelled, and
• time is the total time devoted to the mode of transport (including the time spent at work to earn the money to pay all the costs created by the particular mode of transport).
In the calculation of car speed, the time required for car travel is rarely adequately considered.
Most drivers consider only the time spent in the car while it is moving (and perhaps while it is
idling) when estimating their average speed. They ignore the considerably larger amounts of time that must be devoted to their cars. As well as the time a driver must spend sitting in a car, he or she must spend time earning the money to make the car travel possible. During this time, the driver is effectively going nowhere; hence their speed for this time is zero. When this time is taken into account, along with other time devoted to the car, it is apparent that the car does not save us nearly as much time as we think it saves us.

The implications of this are profound. If our transport goal is to increase speeds (and I am not
arguing that it should be), it is far more effective to spend money on supporting cycling than it is on increasing car speeds. The majority of any increase in trip speed for a cycling commuter is reflected in increased ‘effective speed’. This is reinforced by the fact that as cycling infrastructure improves and more people switch to it, it becomes even more effective. The reverse is true for the car. The more cars that use the roads, the more congestion will slow cars and the higher will be the per kilometre running costs.

Mass car use also involves considerable external costs. One of the major external costs of mass car use involves the generation of greenhouse gas emissions. As well as greenhouse gas emissions, external costs include “costs for congestion, crash risk, roads and parking facilities, traffic services and environmental impacts” (Victoria Transport Policy Institute, 2003). These costs are difficult to measure, but are significant. They are not paid by individual drivers, but are shared by all users. Many of these external costs are not borne by today’s generation: “their full effects felt only by subsequent generations” (Harris et al., 2004). The magnitude of these costs indicates that “reductions in motor vehicle travel can provide substantial benefits to society” (Victoria Transport Policy Institute, 2003).

The health cost of transport related pollution, including in-car pollution is significant. Researchers are only just beginning to understand the full impact of pollution, and recent research indicates that“in-car air pollution may pose one of the greatest modern threats to human health” (International Center for Technology Assessment, 2000, 5). The number of deaths caused by transport related pollution are higher than the number of deaths from vehicle accidents (World Health Organization, 2002). The health cost of the lack of exercise associated with car use should also be considered (Vandegrift and Yoked, 2004). Society pays a heavy cost for the dubious speed advantages of mass car usage.

Non-motorists subsidise all users of motorised transport in Australia. The subsidy to road users has been conservatively estimated to be approximately $8 billion per year (Laird, 2000). If car drivers were required to pay the full cost of using their cars, including parking costs and the environmental and health costs associated with these cars, then their effective speeds would be even lower. About 1/3 of total (car) transport costs are external in North America: " … user costs would need to increase 50% to internalise all costs" (Litman, 1999, 7). If we apply the same multiplier to the Australian case, effective speeds would be as low as 9.6 km/h (for the Toyota Landcruiser), and even a cheap car like the Hyundai Getz would be going much slower than the average cyclist.

A geographic perspective provides an important insight into the issue of speed in cities. Not only is the effective speed of car travel in urban areas lower than we may have thought, we now have to travel further to get to destinations because of the impact of the car. The number of vehicle kilometres travelled is increasing far more rapidly than other indicators; almost three times the rate of population growth in Sydney between 1981 and 1997 (Newton, 2004). Shops, schools and other services are now spread further apart than they were before cars became the dominant mode of transport. People have to travel further now to gain access to the goods and services that they need. This is largely driven by the apparent mobility advantages of the motor vehicle, which have led tothe demise of smaller shops and services close to where people live. Not only do cars give us minimal (if any) advantage in effective speed over such modes as bus, train and cycling, but everybody is further disadvantaged by the extra distances that the car has created. “In the final analysis, the car wastes more time than it saves and creates more distance than it overcomes” (Gorz, 1973).

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