Automobile Dependency
Transportation and Land Use Patterns That Cause High Levels of Automobile Use and Reduced Transport Options
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TDM Encyclopedia
Victoria Transport Policy
Institute
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Updated
August 27, 2007
This chapter describes Automobile Dependency, its causes and implications.
Defining and Measuring Automobile Dependency
Automobile dependency (also called automobile oriented transportation and land use patterns) refers to transportation and land use patterns that favor automobile travel and provide relatively inferior transportation alternatives. In this case, “automobile” includes cars, vans, light trucks, SUVs and motorcycles.
The opposite of Automobile Dependency is not a total lack of private vehicles, rather, it is a balanced or multi-modal transport system, meaning that consumers have a variety of Transport Options, and incentives to use each for what it does best. Efforts to create more balanced transport systems can involve a variety of specific actions to improve travel options, create more multi-modal land use patterns, correct planning and pricing practices that favor automobile travel, and increase the prestige of alternative modes.
Many factors contribute to automobile dependency. During the last century there has been a self-reinforcing cycle of increased automobile travel, reduced travel options, and more automobile-oriented transportation and land use policies which result in a high level of automobile dependency in most communities. Figure 1 illustrates this cycle.
Figure 1 Cycle of Automobile Dependency
Automobile Dependency has many impacts. It increases total mobility, vehicle traffic and associated benefits and costs. It increases the importance of automobile travel and reduces the importance of other modes. In an automobile dependent community virtually every adult needs a personal automobile (as opposed to a household automobile shared by more than one driver). Non-drivers must be chauffeured whenever they travel, and it becomes difficult to withdraw driving privileges for people who are physically, mentally or emotionally unfit, since there are few viable transportation alternatives. Automobile Dependency reduces the range of solutions that can be used to address problems such as traffic congestion, road and parking facility costs, crashes and pollution.
Automobile Dependency is a matter of degree. There are few places in the world that are totally automobile dependent (that is, driving is the only form of transport). Even areas that appear to be highly Automobile Dependent often have a significant amount of walking, cycling and transit travel among certain groups or in certain areas, although use of these modes tends to be undercounted by conventional transportation planning (Measuring Transportation). On the other hand, even Car-Free areas usually have some automobile travel, including emergency and service vehicles, taxis and deliveries.
Several indicators can be used to measure automobile dependency, as summarized in Table 1. A community can be considered highly automobile dependent if more than 80% of personal trips are made by private automobile. Because automobile trips tend to be longer than walking, cycling and transit trips, the majority of personal mileage tends to be by automobile even in communities with balanced transport.
Table 1 Auto Dependency Indicators
|
Indicator |
Description |
Low |
Medium |
High |
|
Vehicle Ownership |
Per capita motor vehicle
ownership (usually measured per 1,000 population) |
Less than 250 per 1,000 pop. |
250-450 |
450+ |
|
Vehicle Travel |
Per capita annual motor
vehicle mileage |
Less than 4,000 miles (6,500 km) |
4,000-8,000 miles (6,500-13,000 kms) |
8,000+ (13,000 km plus) |
|
Vehicle Trips |
Automobile trips as a
portion of total personal trips |
Less than 50% |
50-80% |
80%+ |
|
Quality of Transportation
Alternatives |
Convenience, speed,
comfort, affordability and prestige of walking, cycling and public transit
relative to driving. |
Alternative modes are of competitive quality. |
Alternative modes are somewhat inferior. |
Alternative modes are very inferior. |
|
Relative Mobility Of
Non-Drivers |
Mobility of personal travel
by non-drivers compared with drivers. |
Non-drivers are not severely disadvantaged. |
Non-drivers are moderately disadvantaged. |
Non-drivers are severely disadvantaged. |
|
Market Distortions Favoring
Automobile Use |
Relative advantage provided
to automobile transportation over other modes in planning, funding, tax
policy, etc. |
Minimal bias favoring automobile travel. |
Moderate bias favoring automobile travel. |
Significant bias favoring automobile travel. |
This table summarizes various indicators of automobile dependency. The relative quality of transportation alternatives is the most accurate indicator, but is relatively difficult to measure.
Vehicle ownership is the easiest information to obtain but is the least accurate indicator of Automobile Dependency. A community can have relatively high levels of per capita vehicle ownership, but provide competitive quality walking, cycling and transit service so that automobile owners still rely on alternative modes for a significant portion of their trips, while other communities have relatively low vehicle ownership rates, but poor quality transportation options for non-drivers and so can be considered automobile dependent. The degree of land use Accessibility, the quality of alternative modes, and the amount of bias favoring automobile travel over other modes are the most accurate indicators of Automobile Dependency, although more difficult to measure.
There is no single cause of Automobile Dependency – various mutually supporting factors described in Table 2 both contribute to and result from automobile dependency creating a self-reinforcing cycle of increased automobile ownership and use, more automobile dependent transport and land use patterns, reduced transport options, and further increases in automobile ownership and use.
Table 2 Auto Dependency and Balanced Transportation Compared
|
Factor |
Automobile Dependency |
Balanced Transportation |
|
Motor vehicle ownership |
High per capita motor
vehicle ownership. |
Medium per capita motor
vehicle ownership. |
|
Vehicle travel |
High per capita motor
vehicle mileage. |
Medium per capita motor
vehicle mileage. |
|
Land use density |
Low. Common destinations
are dispersed. |
Medium. Common destinations
are more clustered |
|
Land use mix |
Single-use development
patterns. |
More mixed-use development. |
|
Land for transport |
Large amount for roads and
parking. |
Medium amount devoted to
roads and parking. |
|
Road design |
Road designs emphasize
automobile traffic. |
Road designs support
balance modes and users. |
|
Street scale |
Large scale streets and
blocks. |
Small to medium streets and
blocks. |
|
Traffic speeds |
Maximum traffic speeds. |
Lower traffic speeds. |
|
Pedestrian environments |
Mainly in private malls. |
Mainly on public streets. |
|
Signage |
Large scale, for high speed
traffic. |
Medium scale, for
lower-speed traffic. |
|
Parking |
Generous, free, rigid
requirements. |
Modest, some priced,
flexible requirements. |
|
Site design |
Parking paramount, in front
of buildings. |
Parking sometimes behind
buildings. |
|
Planning Practices |
Non-drivers are a small
minority with little political influence. |
The needs and concerns of
non-drivers significantly influence transportation planning decisions. |
|
Social expectations |
Non-drivers are stigmatized
and their needs given little consideration. |
Non-drivers are not
stigmatized and their needs are considered. |
This table compares various factors related to Automobile Dependency and Balanced Transportation.
Most North American communities are relatively automobile dependent: The majority of households own automobiles and rely on them for most trips. Land use patterns are easily Accessible by automobile but not by other modes. Public policies favor automobile travel, and few resources are devoted to non-automobile transportation. Although consumers have many choices when choosing an automobile and vehicle services, they often have few viable alternatives to driving for mobility.
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Experiencing Automobile
Dependency If
you are a typical motorist, try this experiment: Give up driving for two
typical weeks. This period should require normal travel for work, shopping,
socializing and family obligations. You’ll discover that non-drivers face
many obstacles, including limited travel options, high financial and time
costs, and poor service. As a result you may travel less, foregoing some
trips and choosing more convenient destinations for others. You may
experience embarrassment when asking for a ride or when you use stigmatized
modes such as transit, bicycling and walking. The
problems you experience as a non-driver depend on where you live. If your
community is highly automobile dependent you will experience significant
difficulties. You may have trouble getting to a store or even crossing busy
streets. If your community is multi-modal, with good transit service, bicycle
and pedestrian facilities, you may experience few problems. After two weeks you may be glad to drive again. You may also have experienced some benefits during the period of abstinence. You may discover unexpected joys from walking and bicycling, reduced stress, increased exercise, and friendship with fellow car pool or transit passengers. You may have appreciated being more home-centered and community oriented. You may take pride in reducing pollution, and saving energy. |
As a community becomes more automobile dependent, the people who rely on alternative modes becomes an increasingly small minority, so decision-makers become less familiar with their needs and their political influence declines. As a result, countless public policy and planning decisions become more favorable to automobile travel, and less consideration is given to supporting other modes.
Until recently, public officials and transportation professionals generally considered Automobile Dependency acceptable or even desirable. They assume that Automobile Dependency reflects consumer preferences and is inevitable with increased wealth. They associated automobile travel with comfort, convenience, success and economic development, and alternative modes with deprivation and failure. Most had no experience with efficient, multi-modal transportation systems.
But this assumption is increasingly questioned. Although automobile transportation provides significant benefits to society, these benefits experience diminishing marginal returns. Beyond an optimal level, increased motor vehicle traffic provides little additional benefits, while imposing increasing costs, and reducing the viability of other transport modes. These diminishing marginal benefits occur at both an individual level (although a consumer may benefit from driving 10,000 annual vehicle-miles, few would want to drive 100,000 annual vehicle-miles regardless of how low their financial cost), and at the community level (although a certain amount of vehicle traffic is contributes to economic and social activities, increased vehicle traffic does not necessarily cause more economic and social development). Automobile Dependency is harmful overall because it represents levels of automobile use beyond what is economically and socially optimal (Litman, 2000).
Automobile ownership and use tend to increase with wealth up
to a point, but they eventually reach saturation. An international study found
that per capita automobile ownership peaks at about $21,000 (1996 U.S. dollars)
annual income and levels off, or even declines due to increased congestion,
loss of novelty, and public policy responses (Talukadar, 1997). Using
Factors That Contribute to Automobile Dependency
A number of transportation and land use market distortions tend to encourage automobile ownership and use beyond what is economically and socially optimal (Market Principles). These include underpricing, inadequate consumer choice, weak competition, bias in transportation planning and investment practices, and other public policies that favor automobile travel.
Conventional Transportation Planning practices can create a self-fulfilling prophecy: past traffic growth rates are extrapolated to predict future vehicle traffic demand, and road and parking capacity is built to meet this projected demand (called predict and provide planning). Little consideration is given to the negative impacts that more dispersed destinations, larger roads and parking facilities, and reduced resources for other travel modes will have on overall Accessibility. The result is increasingly automobile-oriented transportation systems and land use patterns (Condon, 2004). More Comprehensive Planning can help create more balanced transportation systems.
Transportation Evaluation practices often favor automobile dependency. Transportation service quality is often Measured primarily in terms of vehicle traffic (e.g., roadway level of service, average traffic speed, vehicle congestion delay), with little or no consideration to other modes. Nonmotorized Transportation tends to be undervalued in conventional transportation surveys and Models, which ignore or undercount short trips, travel by children, leisure travel, and walking links to access automobiles and transit service. As a result, few resources are devoted to walking and cycling.
Current investment practices also contribute to Automobile Dependency. Transportation funding is often dedicated to roads and parking, and cannot be used for other types of transportation facilities or services, even when they are more cost effective overall. Zoning codes often include minimum parking requirements, which represent a subsidy of automobile travel, and by increasing land requirements, results in lower-density, urban fringe development. Least Cost Transportation Planning, Smart Growth Policy Reforms and Parking Management are TDM strategies that can help correct these distortions.
Automobile use is considered Prestigious, while other mode are stigmatized, many urban communities have become unattractive to middle-class residents, and some people assume, incorrectly, that automobile dependency contributes to Economic Development. The public officials and community leaders most involved in transportation planning tend to be automobile dependent, and so are particularly conscious of problems facing motorists and less aware of problems facing people who depend on other modes. This is not to suggest that public officials are unconcerned about the negative impacts of increased vehicle traffic and problems facing non-drivers. Many work hard to improve Transport Options. However, this occurs despite, rather than supported by current transportation evaluation and planning practices.
While it may seem harmful to constrain road building just to reduce automobile dependency, a more positive perspective, which often reaches the same conclusion, is that once a community has a basic road system which provides motor vehicle access to most destinations, increasing traffic capacity and speed provides diminishing benefits and increasing costs, so it makes sense to invest an increasing portion of resources in alternative modes and more accessible land use patterns in order to achieve community planning objectives. There is a strong economic case for transportation and land use policies that increase the cost of driving (Market Reforms), reduce sprawl (Land Use Evaluation) and increase Transport Options (Litman, 2000).
|
No One Goes There Anymore. It’s Too Crowded. By
Peter Jacobsen Does
improving drivability improve economic wealth? In
2003, Sperling's BestPlaces ranked 77 Curiously
enough, the least drivable cities appear to be thriving economically.
Comparing drivability against per capita income (Commerce Department shows
that the average per capita income of the ten least drivable cities is over
half again greater than the ten most drivable cities, www.bea.doc.gov/bea/regional/data.htm),
as illustrated below. Figure 2 Annual
Per Capita Income
(MSN, 2003; BEA, 2003)
The ten U.S. communities ranked least sprawled have much lower average annual per capita incomes than the ten communities that are ranked most sprawled. Although
Yogi Berra was thinking of |
Benefits and Costs
This section describes various categories of costs and benefits caused by Automobile Dependency.
Benefits
Increased Mobility
Automobile dependent transportation systems have high capacity roads and abundant parking, which maximizes automobile travel speed and convenience, and increases total personal mobility.
Affordable Vehicle Travel
Automobile Dependency is associated with minimal taxes on vehicle ownership and fuel, minimal tolls and parking fees, highly competitive markets for vehicles and vehicle services, making vehicle ownership relatively affordable even to lower-income households. Automobile Dependency tends to increase access to urban fringe land, increasing housing affordability, although this is partly offset by higher parking and public service costs (Land Use Evaluation).
Economic Development
Some businesses benefit from automobile dependency, including those involved in vehicle and fuel production, motor vehicle services, and automobile-dependent destinations (such as suburban housing and malls). However, as discussed later, this is offset by disbenefits to other businesses.
Costs
Transportation Expenditures
Although Automobile Dependency tends to minimize per-mile Vehicle Costs (fuel taxes, road tolls, parking fees, etc.), it tends to increase total vehicle costs by increasing per capita vehicle ownership and use. As a result, total transportation expenditures tend to increase with automobile dependency (Newman and Kenworthy, 1999, pp. 111-117; McCann, 2000; Litman, 2003, Table 13). McCann (2000) found that households in more automobile dependent communities devote more than 20% of household expenditures to surface transportation (over $8,500 annually), while those in communities with more diverse transportation systems spend less than 17% (under $5,500 annually). The cost to consumers is even greater because motor vehicle expenditures provide little long-term economic benefit: $10,000 spent on motor vehicles provides just $910 in equity, compared with $4,730 for the same investment in housing (McCann, 2000). This suggests that shifting consumer expenditures from motor vehicles to investments such as housing, education or savings can increase personal wealth.
Litman (2003) found that residents of the Smartest Growth U.S. cities spend 6% less of their income on combined transport, housing and food than residents of sprawled cities.
Consider another perspective. Table 3 compares the typical annual costs of a 10-mile urban-peak commute by different modes. It assumes that vanpool operating costs average 24˘ per mile, transit operating costs average $6.00 per bus-mile, and transit vehicles impose twice the roadway capacity and four times the external costs of an average automobile.
Table 3 Costs of Urban Commute (Transportation Costs)
|
Mode |
Auto Costs |
Automobile |
Carpool |
Vanpool |
Transit |
|
Passengers |
|
1 |
3 |
10 |
30 |
|
Vehicle Ownership |
$3,000/year |
$3,000 |
$1,000 |
$300 |
$0 |
|
Vehicle Operation |
12˘/vehicle-mile |
$600 |
$200 |
$120 |
$1,000 |
|
Highway Capacity |
50˘/vehicle-mile |
$2,500 |
$833 |
$250 |
$167 |
|
Parking |
$1,000/year |
$1,000 |
$333 |
$33 |
$0.00 |
|
Externalities |
10˘/vehicle-mile |
$500 |
$167 |
$50 |
$67 |
|
Totals |
|
$7,600 |
$2,533 |
$753 |
$1,233 |
|
Savings |
|
$0 |
$5,067 |
$6,847 |
$6,367 |
Alternative modes can provide significant annual savings over SOV commutes.
An average employee earns about $33,000 annually. Assuming that about half of urban automobile commutes could shift to more efficient alternative modes if given suitable incentives, the additional $6,000 in annual commuting costs associated with automobile-dependency, represents about a 10% surcharge on wages. Put another way, TDM programs can reduce urban employment costs by about 10% by providing commute cost savings. These various studies and perspectives indicate that Automobile Dependency reduces overall transportation Affordability.
Infrastructure Costs
By increasing per capita automobile ownership and use, Automobile Dependency increases costs for roads, Parking and traffic services by hundreds of dollars annually per capita (Transportation Costs). Many of these costs are borne indirectly through taxes, business overhead expenses, and housing costs.
Reduced Land Use Accessibility
Automobile Dependency creates less Accessible land use patterns, meaning that destinations are more dispersed, less mixed and less connected. This requires more mobility to maintain a given level of accessibility.
Reduced Transport Options
If resources (money and space) were unlimited, and motor vehicle travel imposed no significant safety or pollution impacts on other modes of travel, and transportation policy decisions were always balanced, it might be possible for an automobile dependent community to maintain a good range of Transport Options. But these conditions do not exist. Transportation resources are limited, motor vehicle traffic degrades nonmotorized travel conditions (and therefore the feasibility of transit), and in automobile dependent communities, decision-makers tend to be less concerned with the needs of non-drivers. In practice, increased automobile dependency tends to reduce the quantity and quality of transportation alternatives.
The costs of automobile dependency consist, in part, of reduced benefits from a more diversified transport system. There are several specific benefits from transport diversity:
·
Solving Transportation Problems. Improved Transport Options is often the most cost
effective way to address traffic congestion, facility costs, road risk,
environmental impacts and consumer costs. Automobile dependency reduces the
range of solutions that can be applied to such problems.
·
Consumers benefits. Improved options allows consumers to save money, avoid stress, and
reduce their need to chauffeur non-drivers.
·
Efficiency. Consumer choice is necessary for economic efficiency (Market Principles). Improved
transportation choice allows consumers to choose the most efficient option for
each trip.
·
Equity. Inadequate transport options often limits the personal and economic
opportunities available to people who are physically, economically or socially
disadvantaged. Increasing transportation options can help achieve equity
objectives.
·
Livability. Many people value living in
or visiting a community where walking and cycling are safe, pleasant and
common. There are also public Health
benefits from increased walking and cycling. As a result, transportation
options can help communities become more “livable,” resulting in increased
property values and commercial activity.
·
Security and Resilience. Improved transportation
options results in a more diverse and flexible transportation system that can
accommodate variable and unpredictable conditions. Even people who do not
currently use a particular form of transport may value its availability as a
form of insurance to accommodate future needs.
The transport problems facing non-drivers in an automobile-dependent community can be defined in two different ways which suggest two different types of solutions. One defines the problem in terms of inadequate mobility, which suggests solutions such as making cars more affordable and subsidizing special bus services. The other approach defines the problems in terms of inadequate Accessibility, which suggest solutions that involve reducing the overall degree of Automobile Dependency and changing transport and land use policies. For example, to insure that students in transport disadvantaged households can get to school, officials can either fund special bus services (a mobility-oriented solution), or they can locate schools and manage road systems to insure that most students can easily walk to schools (an accessibility-oriented solution). Of course, most communities use a combination of both approaches, but some tend to emphasize one or another. In general, accessibility-oriented solutions tend to provide the broadest range of benefits to people who are transport disadvantaged.
Transportation System Cost Efficiency
Transit services and pedestrian facilities experience economies of scale: unit costs decline as the number of users increase, resulting in better facilities and services, and better integration with other components of the transportation system. More balanced transportation increases the efficiency of alternative modes.
Automobile dependent regions have lower transit system cost recovery (Newman and Kenworthy, 1999; Litman, 2004). Similarly, automobile dependency reduces the cost effectiveness of nonmotorized modes. Sidewalks and paths are not considered worthwhile investments in Automobile Dependent areas, because they receive little use. Communities must either provide less service or increase subsidies to maintain a given level of transportation options.
Traffic Crashes
Although Automobile Dependency includes vehicle and highway improvements that tend to reduce per-mile crash rates, they encourage more and faster driving, which increases total crashes (Evaluating Safety Impacts). This explains why per capita traffic deaths are far higher in sprawled communities, as illustrated in Figure 3.
Figure 3 Annual
Traffic Death Rate (
The ten U.S. communities ranked least sprawled have much lower annual traffic fatality rates than the ten communities that are ranked most sprawled.
Health Impacts
Automobile-oriented transportation systems are associated with reduced exercise and unhealthy weight gains, and TDM strategies that increase walking and cycling can provide significant health benefits (Health Impacts). Many experts believe that increasing active transportation (walking, cycling, running and skating) is the most practical and effective way to improve public fitness. One major study concluded, “Regular walking and cycling are the only realistic way that the population as a whole can get the daily half hour of moderate exercise which is the minimum level needed to keep reasonably fit” (Physical Activity Task Force, 1995).
Congestion
Automobile Dependent transportation and land use patterns result, in part, from efforts to reduce Traffic Congestion by continually increasing roadway system capacity and design speeds. However, this tends to be offset by increased per capita vehicle mile