Transportation's Role in Reducing U.S. Greenhouse Gas Emissions ...

Transportation’s Role in Reducing U.S. Greenhouse Gas Emissions: Volume 2
million passenger miles were reduced, resulting in the reduction of 1,250 tons of GHG
emissions (State of Connecticut, 2007) or 0.42 tons per vanpooler. If this benefit were
extrapolated to a hypothetical participation of 2 percent of the workforce in the 50 largest
metropolitan areas, and netting out the current participation of 0.3 percent, the result
would be 1.22 million new vanpoolers and a reduction in greenhouse gas emissions of
0.5 mmt CO2e at current vehicle efficiencies. An alternative calculation using the same
hypothetical 2 percent participation rate, combined with other generic assumptions about
participation, mileage, and trips displaced, yields an estimated reduction of 1.3 mmt
CO2e. 38
Ridesharing and vanpooling programs can be established quickly, within less than a year
to develop appropriate ridematching tools and marketing/outreach materials. Successful
programs should grow over time; however, maximum benefits should be realized within a
few years.
Cost-Effectiveness
Ridesharing program costs consist primarily of administrative expenses along with
marketing and outreach to promote the program. Results of carpool program evaluations
from the 1970s found a project cost of $47 per new carpooler captured, or $0.024 per
vehicle-mile reduced over the project life (Wagner, 1978), or $0.08 per mile in 2008 dollars.
The 1994 literature review estimated a cost-effectiveness of $0.60 per vehicle round-trip
avoided for areawide ridesharing programs (Apogee, 1994), which at an average of 12
miles per one-way trip and inflating to 2008 dollars translates into $0.04 per vehicle-mile
reduced. Based on this estimate the cost-effectiveness of areawide ridesharing programs
would be about $80 per ton CO2e reduced. A net cost savings would be realized if private
vehicle operating cost savings are included. 39
The administrative costs associated with
rideshare matching programs are quite small compared to the costs that are required for a
broadly effective marketing and outreach campaign, and are likely to have declined
further with the advent of Internet technology.
Vanpool costs include purchase and operating costs for the vehicle as well as
administrative expenses. Costs are offset by vehicle operating cost savings to individuals,
meaning that vanpool programs can cover most, if not all, of their costs through
38 The alternative calculation assumes an average vanpool occupancy of six persons, one-way
vanpool trip length of 35 miles versus 20 miles for previous solo drivers, average mpg of 12.0 for a
van versus 20.6 for a car, 75 percent prior SOV mode share, and four days per vanpooler per week.
The fuel savings per occupant is about 50 percent of their daily commute fuel use (0.97 gallons per
vanpooler per day).
39 At a round-trip length of 24 miles and a cost of $0.55 per mile per current Internal Revenue Service
(IRS) guidance (as of January 2009), the typical commuter could theoretically save about $13 per
day (although the actual savings may be less as this includes some fixed costs such as insurance).
Even at half the IRS value per mile, user cost savings are still considerably greater than the $0.04
per-mile cost estimate.
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