Trail users on Washington D.C.'s Capital Crescent Trail. | Photo by RTC/Barbara Richey
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Introduction and Methodology

In 2008, RTC published a groundbreaking report, “Active Transportation for America,” which quantified the national benefits of active transportation—for the first time. These calculations, based on the most recent National Household Travel Survey data at that time (2001) and various scenario assumptions, showed that increasing active transportation would provide tens of billions of dollars in benefits.

We have since recalculated the benefits of active transportation with more recent data from the 2009 survey and updated our methodologies. From 2001 to 2009, the average distance traveled by walking per person per year increased from 102.2 miles to 113.15 miles (0.28 to 0.31 miles per day), and the average distance cycled increased from 18.25 miles to 25.55 miles (0.05 to 0.07 miles per day).

There is a lot more room for growth in walking and biking. As of 2009, nearly half of all trips in the U.S. are less than three miles, and more than one-quarter of trips are less than one mile. Yet, most of these short trips are taken by private vehicle. What if the growth in walking and biking that happened between 2001 and 2009 continued into the future?

We extrapolated current walking and biking trips into the future to estimate the impacts and benefits of active transportation under two growth-model scenarios. In the first model, the “conservative growth” scenario, active-transportation usage increases by a constant of an additional 495,000 miles traveled by active transportation per year (calculated as the average yearly growth from 2001 and 2009 National Household Travel Survey data). The second model presents a more pronounced growth. In the “double growth” scenario, active transportation in the future grows at double the average rate of growth from 2001-2009 (about 4 percent per year). Then we asked, what are these trips worth?

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Congestion Benefits in Miles Driven Avoided

If the 37 billion miles walked and biked in the U.S. in 2009 were instead driven, the reality is that our transportation system would gridlock in some places, even though walking and biking comprise only a small portion of all person miles of travel. Traffic data services provider INRIX reported that the 3 percent drop in vehicle miles traveled in the economic crisis of 2008 produced a 30 percent drop in peak period congestion during that year.

The congestion avoidance benefits of walking and bicycling alone are astounding. For example, at the Hawthorne Bridge in Portland, Ore., between 1991 and 2010, the number of vehicles on the bridge increased by 20 percent, but because most of these vehicles were bicycles, congestion remained the same. Without the protected bicycle lane to accommodate riders, automotive congestion could have become significantly worse.

Table 1. Miles driven avoided due to bicycling and walking | View Full Image →

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Fuel Savings and Carbon Dioxide Emissions Avoided

Examining walking and bicycling trips as potentially avoided driving trips suggests additional ways to provide a baseline value for these journeys: 849 million gallons of fuel saved, valued at $4 billion in gasoline not spent in 2009, and 14 million tons of carbon dioxide not emitted, conservatively worth an additional $147 million. In the conservative growth scenario for 2030, the fuel and carbon dioxide savings from active-transportation use are offset by higher fuel standards (miles per gallons). However, in the double growth scenario, the overall quantity of increase in active-transportation usage outweighs any projected higher fuel standards.

Table 2. Gallons of fuel saved due to bicycling and walking | View Full Image →
Table 3. Tons of CO2 saved due to bicycling and walking | View Full Image →

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Health Benefits

These numbers have real significance for American household budgets. However, there is a growing awareness that the health benefits of walking and bicycling have truly major financial implications not only for individuals, but also society, given that state governments and the federal government pay 44 percent of healthcare costs in the U.S. The World Health Organization has recently published a simple to use Health Economic Assessment Tool, which assesses the reduction in premature mortality resulting from physical activity from walking and cycling. In this tool, each avoided premature death is valued with the so-called “value of a statistical life (VSL),” a measure routinely used in government transportation project evaluations (e.g., in safety analysis). The current baseline VSL, used by the National Highway Traffic Safety Administration,is $9.1 million (2009) per person. The health benefits from active transportation that result in the prevention of premature deaths added up to a value of $235 billion per year in 2009.

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Total Monetary Value of Walking and Bicycling for 2009 and 2030

By 2020, overall benefits will reach a value of between $300 billion (for the conservative growth scenario) to $400 billion (for the double growth scenario). By 2030, these will increase to between $400 billion (conservative growth) to $700 billion (double growth).

Table 4. Monetary value of benefits from bicycling and walking | View Full Image →

These benefit calculations are based on a set of assumptions, and the wide range of uncertainty about how to precisely measure these benefits and predict the growth of walking and bicycling in the future is shown in the wide range of possible benefits. Additionally, many types of benefits, such as local economic impacts, are not quantified due to lack of data. Therefore, the total benefits could be higher.

Figure 1. Active transportation benefits from fuel savings, reduced CO2 emissions and reduced premature mortality. | View Full Image →

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Calculation Assumptions

Benefit calculations are highly dependent on assumptions. Here are ours:

  • Calculations are based on miles traveled by foot and bike, as reported in the National Household Travel Surveys of 2001 and 2009.
  • Benefit calculations are conducted separately for short trips up to one mile and trips of one to three miles, as trips less than one mile are typically taken by walking, and trips from one to three miles are more often conducted by bicycle.
  • In addition, benefits from an increase in transit trips of one to 15 miles are calculated because of greater access provided by walking or bicycling to a transit location stop.
  • Three types of benefits are calculated:
       o   Fuel savings
       o   Reductions in CO2 emissions
       o   Health benefits in terms of reduction in premature mortality
  • Fuel savings are based on CAFE standard values, which are discounted by 20 percent to reflect a discrepancy between actual mileage (Label mpg) and CAFE mpg. The CAFE values used assume a 50/50 split between cars and light trucks. Future CAFE values are extrapolated up to a level of proposed 2025 CAFE standards of 49.6mpg (by NHTSA). This extrapolation assumes that by 2030, 25 percent of the fleet (all new cars since 2025, assuming a 20 years fleet turnover rate) has reached this value. For the remaining 75 percent of the fleet, the average mpg between 2010 and 2030 is applied.
  • Transit is assumed to require 25 percent less fuel than driving per person-mile.
  • From 2001 to 2013, average U.S. fuel prices were used. Thereafter, for the “conservative growth” scenario, we use the average fuel price from 2006 to 2013 ($3.10) and apply a 3 percent annual increase. For the “double growth” scenario we use the 2013 average gas price ($3.60) and apply a 3 percent annual increase.
  • COemissions are 19.6 pounds per gallon of fuel saved, valued at $10 per metric ton.
  • Health benefits calculation is based on the HEAT method, using the following data:
       o   Mortality rate for 15 to 74 years old: 457/100,000 (for walking)
       o   Mortality rate for 15 to 64 years old: 310/100,000 (for cycling)
       o   Mortality reduction due to walking: 11 percent/11.25METs (MET = Metabolic Equivalent of Task) (approximately three hours per week at 3.3 miles per hour (mph)
       o   Mortality reduction due to cycling: 10 percent/11.25METs (approximately 90 minutes per week at 11mph)
       o   Each avoided premature death is valued at $9.1 million in 2009 (thereafter increased by 1.07 percent per year).
  • Future benefits are based on two different extrapolations of miles traveled in the future:
       o   The conservative growth scenario assumes the same steady (constant, linear) growth in active-transportation miles as between 2001 and 2009 (increase of 435,000 miles per year).
       o   The double growth scenario assumes a doubling in the growth rate of active-transportation miles after 2009 (compared to the growth rate between 2001 and 2009; between 3 percent and 6 percent per year, depending on trip category).

Want More Info?
For further information about the calculations here, contact our policy team.