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Travel Impacts

Automobile Dependency typically doubles automobile ownership and use, and associated Costs, including vehicle ownership and operating costs (and therefore the portion of household budgets devoted to transportation), road and parking infrastructure costs, per capita traffic fatality, energy consumption, pollution emissions and land use consumption. These impacts can be perceived by comparing travel patterns between transit-oriented and sprawled neighborhoods in U.S. cities (Figure 3), by comparing differences in travel patterns between multi-modal and more sprawled U.S. cities (such as between Davis, California where residents average 13.9 daily vehicle-miles and Houston, Texas where residents average 34.0 daily vehicle-miles), and by comparing U.S. travel patterns with those of other wealthy countries, such as Norway and Switzerland. For example, U.S. residents devote approximately 20% of household incomes to transportation (motor vehicles, public transit and residential parking), which is about twice the amount spent on average by Swiss residents. Interestingly, there are no measurable differences in the amount of time that people spend on transportation between multi-modal and automobile dependent locations; residents of more automobile-oriented communities are able to travel somewhat faster, but their destinations are more dispersed so they save no time overall.



Figure 3 TOD Impacts On Transport Activity in Portland, Oregon (Ohland and Poticha 2006)



People who live in transit-oriented developments drive less and rely more on alternative modes. “Daily VMT” indicates average daily vehicle miles traveled per capita.

By creating more dispersed Land Use patterns and reducing transportation Options, Automobile Dependency tends to significantly increase per capita vehicle travel and reduce use of alternative modes. For example, U.S. residents drive about twice as many annual miles as German residents of similar incomes living in communities with similar densities due to a combination of lower fuel prices and reduced transportation options (Buehler 2009) In Automobile dependent communities households use automobiles for most trips. In Transit Oriented communities they rely on a mix of modes. In Carfree communities, most trips are by non-motorized modes and public transit, automobile travel is reserved for work trips (such as delivery and service vehicles) and out-of-town travel, as illustrated in the table below.



Table 2 Typical Mode Share By Trip Purpose For Various Transport Systems

Trip Purpose

Automobile Dependent

Transit Oriented Development

Carfree

Work commuting







School commuting







Work-related business







Personal travel (errands)







Social and recreation







Total car trips

21

9

3

Total transit trips

1

5

6

Total non-motorized trips

3

11

16

Total trips

25

25

25

Residents of automobile-dependent communities use automobiles for most trips. Transit oriented development results in the use of mixed modes. Carfree development results in minimal driving.

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 – Inequity

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.

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