2 emissions attributable to different
commuter transportation modes (see Table F.1). Calculations are
performed for a 10-mile commuting trip, which is the national
average (Pisarski, 1987).
The second step is to calculate the way in which solo commuters
will redistribute themselves among alternative transportation modes
in response to parking restrictions. This analysis assumes that the
percentage of those who use bus, rail, carpool, or vanpool will be
proportional to the current "mode split" (excluding pedestrians and
those who work at home). Where
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TABLE F.1 Carbon Dioxide Emissions by Commuting Mode
(tons/year)
Mode
Btu per Passenger Milea
Yearly Energy (MBtu)b
Equivalent Gallons Gasolinec
Amount of Yearly CO2 Emissionsd
Difference from Solo Driving
Solo driving
8,333
41.66
333.3
2.98
—
Bus
2,121
14.77
118.2
1.06
1.92
Rail
1,935
13.84
110.7
0.99
1.99
Carpool
3,788
18.94
151.5
1.36
1.62
Vanpool
882
8.58
68.6
0.61
2.37
aFor solo
drivers, the figure is per vehicle-mile for automobile
commuting.
bEnergy
use = (Btu per passenger-mile) × (10 miles per commuting
trip) × (2 trips per day) × (250 commuting days per
year). In addition, for bus, rail, and vanpool modes, it is assumed
that commuters drive alone 1 mile (at 8333 Btu/mi) each way per day
to get to the transfer point. For rail, energy use for commuter
rail is used (rather than the lower energy use for transit
rail).
cAssumes
that 1 gallon of gasoline = 125,000 Btu (Davis et al., 1989).
d(Gasoline
usage) × (19.7 lbs CO2/gal
gasoline)/(2200 lb/t).
parking spaces are eliminated, it is assumed that none of the 9
million displaced solo commuters continue to drive alone, and all
are divided among the four remaining modes. Where parking spaces
are priced to reduce the solo driver mode share to 50 percent, the
shares for the remaining modes are proportional to those calculated
for elimination of parking spaces. (To account for the remaining
solo drivers, the other mode shares add up to 50 percent, rather
than 100 percent, of all commuters.) The mode splits for displaced
drivers are presented in Table F.2.
These mode splits are then applied to the 9 million solo drivers
affected by the parking elimination component and the 27 million
solo drivers affected by the parking management component. As shown
in Table F.3, the combination of these two measures would produce
annual emission reductions of 49 Mt of CO2.
Calculation of Cost-Effectiveness
A parking demand management program of the type described in
this appendix would involve several types of costs and savings:
• employees' out-of-pocket costs or savings from the use of
alternative transportation modes (a figure that includes fuel
savings);
• employers' out-of-pocket operational costs or savings
from parking management and provision of transportation
alternatives;
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TABLE F.2 Calculation of Mode Shares for Multiple
Occupancy Vehicle Modes When Parking Spaces Are Eliminated or
Restricted
Current Mode Share (%)
Elimination—Adjusted Mode Share (%)a
Surcharge—Adjusted Mode Share (%)b
Solo driving
64.4
0.0
50.0
Public transit
Bus
5.2
19.3
9.6
Rail
2.8
10.4
5.2
Group ridec
Carpool
16.8
62.2
31.1
Vanpool
2.2
8.1
4.1
aAssumes
no solo driving; share of each mode when considering only the 20.09
million metropolitan commuters currently commuting by bus, rail,
and group (carpool and vanpool) ride (Pisarski, 1987).
bAssumes
50 percent solo driving; share of other modes calculated by halving
adjusted mode shares calculated (in column 2) when all solo driving
is eliminated.
cPisarski
(1987) gives the "group ride" mode share as 19 percent but does not
give separate mode shares for carpooling and vanpooling. The
assumed mode shares are based on the proportion of carpooling to
vanpooling in Table 3-17 of Pisarski (1987) (20.1 percent
carpooling versus 2.6 percent vanpooling) and the census estimate
that 1.6 million people used vanpools in 1980.
TABLE F.3 Carbon Dioxide Emission Reductions from Parking
Management Program
Mode
New Passenger Trips—Parking Elimination
(million trips/yr)a
New Passenger Trips—Parking Surcharge
(million trips/yr)b
Total New Passenger Trips (million trips/yr)c
CO2 Emission
Reduction (Mt/yr)
Bus
1.74
2.59
4.33
8.31
Rail
0.94
1.40
2.34
4.66
Carpool
5.59
8.40
13.99
33.16
Vanpool
0.73
1.11
1.84
2.98
TOTAL
9.0
13.5
22.5
49.05
aApplication of mode shares from table F.2 to 9 million
solo drivers affected by elimination of parking spaces.
bApplication of mode shares from Table F.2 to 27 million
solo drivers affected by surcharges on parking spaces, 13.5 million
of them continue to solo commute.
cMultiply
total new trips for each mode by CO2
emission reductions, compared to solo driving, from Table F.1.
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• employers' capital savings from the avoided costs of
constructing parking spaces; and
• monetized costs or savings from changes in the lengths of
commuting trips.
The first category—employees' out-of-pocket costs—is
calculated by considering costs such as variable automobile
operating expenses, bus and train fares, and vanpool fees. The
second category—employers' operational costs—involves
increased costs for running carpool and vanpool programs, offset by
savings from avoiding the annual operating and maintenance costs of
providing parking spaces for bus, rail, and some ridesharing
commuters. The third category—employers' capital
savings—represents the avoided costs of constructing parking
spaces at an average investment of $3000 per space. Finally,
changes in the length of commuting trips cause productivity losses
or gains that can be monetized.
TABLE F.4 Combined Employer/Employee Out-of-Pocket
Costs/Savings of Alternative Commuting Modes per Daily Round Trip
Commute (1987 dollars)
Mode
Worker Cost ($)
Employer Cost ($)
Total Cost ($)
Difference from Solo Driving ($)
Solo driving
1.44a
0.26b
1.70
—
Bus
1.24c
-0.26d
0.98
-0.72
Commuter rail
2.60e
-0.26d
2.34
0.64
Carpool
0.65f
-0.22g
0.87
-0.83
Vanpool
2.40h
0.04i
2.44
0.74
aBased on
7.31 cents per mile for 1987 variable operating costs of an
automobile (Davis et al., 1989) for 20-mile round trip.
bBased on
average employer cost of $64 per year to operate a parking space
(Wegmann, 1989).
cRounded,
based on 1987 average one-way transit trip cost of $0.62 (U.S. DOT,
1989).
dEmployer
savings from not providing a parking space for bus rail riders.
eBased on
1987 average commuter rail fare equivalent to $0.13 per mile (U.S.
DOT, 1989) for a 20-mile round trip.
fAssumes
that an average of 2.2 persons (Pisarski, 1987) splits the cost of
solo driving.
gBased on
providing 1/2.2 (average carpool occupancy) of a parking space and
administrative costs of $25 per employee for carpool matching
program.
hBased on
monthly fare of $50 per vanpool rider (Toruemke and Roseman,
1989).
iBased on
providing 1/10.7 (average vanpool occupancy) of a parking space and
employer administrative costs of $4.50 per employee per year for
running vanpool program.
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TABLE F.5 Out-of-Pocket Employee and Employer Savings
from Switching from Solo Driving to Other Commuting Modes
Mode
New Passenger Trips (million)a
Commuting Cost Differential ($ billion)b
Bus
4.33
-3.12
Rail
2.34
1.50
Carpool
13.99
-11.61
Vanpool
1.84
1.36
TOTAL
-11.87
NOTE: Not counting avoided cost of constructing
parking spaces and productivity gains/losses.
aFrom
Table F.3.
bNumber of
new passenger trips multiplied by cost differential per trip from
Table F.4.
The first two categories of costs are elaborated in Table F.4.
Once the cost per commuter trip for each mode is calculated, the
total out-of-pocket costs/savings of a parking management program
are calculated by multiplying the number of former solo commuters
using each alternative mode by the cost differential. The results
are presented in Table F.5. Savings to both workers and employers
exceed costs, resulting in an overall program savings of -$12
million.
In addition to these savings, employers save money by avoiding
the capital costs of providing parking. Constructing a parking
space costs between $1,000 and $15,000 (Institute of Transportation
Engineers, 1989), with one survey finding an average cost for added
spaces of $3,920 (Wegmann, 1988). Even if a space has already been
constructed, employers can realize savings from eliminating the use
of the space for employee parking and using the space for paid,
commercial parking or other purposes. This parking management
program would eliminate the need for 16.9 million parking spaces, 9
million directly eliminated and 7.9 million freed when solo
commuters shift to less parking-intensive modes. If only 10 percent
(or 1.69 million parking spaces) are spaces that would otherwise
have been built at an average construction cost of $3000, the total
employer capital cost savings is $5.1 billion.
Finally, the program will change the length of commuting trips
in two ways. First, traffic congestion will be reduced because 22.5
million solo commuting cars will be replaced by 6.7 million buses,
carpools, vanpools,
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TABLE F.6 Changes in Annual Commuting Time for Different
Modes Relative to Base-Case Solo Commuting Without Parking
Management
5 Percent Increase in Speedb
20 Percent Increase in Speedc
Mode
Base-Case Speeda (mph)
Speed (mph)
Delay/Savings (hours)d
Speed (mph)
Delay/Savings (hours)d
Solo driving
32
34
(8)
38
(25)
Bus
13
14
200
16
150
Rail
23
23
58
26
58
Carpool
32
34
(8)
38
(25)
Vanpool
29
30
(8)
35
(17)
aTravel
speeds for solo driver, bus, and rail are from Table 3-23 in
Pisarski (1987). Although Pisarski lists the speed for carpoolers
at a faster 34 mph, this was adjusted to 32 mph to account for
pickups/drop-offs. The speed for vanpooling was estimated at 10
percent slower than carpooling to account for additional
pickups/drop-offs.
bThis case
assumes that travel speeds for highway modes (solo driver, bus,
carpool, and vanpool) increase 5 percent relative to the base case
due to reduced traffic congestion.
cThis case
assumes that travel speeds for highway modes (solo driver, bus,
carpool, and vanpool) increase 20 percent relative to the base case
due to reduced traffic congestion.
dTime
delays/savings are compared to the base case for solo commuters.
Annual travel time is based on 250 round-trip commutes annually,
with an average trip length of 10 miles each way (Pisarski,
1987).
and solo commuters. With one-third fewer commuter vehicles on
the road during peak hours (there are currently 48 million solo
commuters in metropolitan areas of the United States), traffic
congestion will be reduced and travel speeds increased for all
highway modes (solo drivers, carpools, vanpools, buses). This
analysis considers two scenarios, one in which travel speed is
increased by 5 percent and one in which travel speed is increased
by 20 percent.
Trip lengths will also change because shifting to modes such as
buses and vanpools will increase commuting times relative to solo
automobile travel. Data presented in Pisarski (1987) indicate that
commuting by bus and rail is slower than commuting by automobile.
Table F.6 calculates the relative changes in annual commuting time
accounting for both of these factors. Table F.7 then converts these
figures into total commuting time delays/gains and monetizes the
resulting productivity changes at values ranging from $5 to $10 per
hour. These figures are consistent with values of $5 to
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TABLE F.7 Monetized Value of Changes in Trip Lengths Due
to Parking Management Program Relative to Base-Case Solo
Commuting
5 Percent Increase in Speedb
20 Percent Increase in Speedc
Mode
Number of New Passenger Trips (million
trips/year)a
Change in Travel Time (hours/persons/yr)d
Change in Value of Travel Time (G$/yr)e
Change in Travel Time (hours/persons/yr)d
Change in Value of Travel Time (G$/yr)f
Solo driving
13.50
(8)
(1.08)
(25)
(1.69)
Bus
4.33
200
8.66
150
3.25
Rail
2.34
58
1.36
58
0.68
Carpool
13.99
(8)
(1.12)
(25)
(1.75)
Vanpool
1.84
(8)
(0.15)
(17)
(0.16)
TOTAL
7.67
0.33
aFrom
Table F.3.
bThis case
assumes that travel speeds for highway modes (solo driver, bus,
carpool, and vanpool) increase 5 percent relative to the base case
due to reduced traffic congestion.
cThis case
assumes that travel speeds for highway modes (solo driver, bus,
carpool, and vanpool) increase 20 percent relative to the base case
due to reduced traffic congestion.
dFrom
Table F.6.
eEach hour
of change in travel is valued at $10, as explained in the text.
Total savings is (number of passenger trips) × (hours of
delay or savings) × ($10 per hour).
fEach hour
of change in travel is valued at $5, as explained in the text.
Total savings is (number of passenger trips) × (hours of
delay or savings) × ($5 per hour).
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$7 per hour used by the Federal Highway Administration and
transportation researchers to value time spent in traffic delays
(U.S. General Accounting Office, 1989; Wegmann, 1989). (Only the
upper-bound and lower-bound cases are presented in Table F.7; the
lower bound assumes a 20 percent increase in highway speed and
values delays at $5 per hour, while the upper bound assumes a 5
percent increase in highway speed and values delays at $10 per
hour.)
Thus the total cost of this parking management program is as
follows:
Out-of-pocket costs (employers and employees)
($0.01 billion)
Avoided parking space construction
($5.07 billion)
Productivity gains/losses
$0.33 billion to $7.67 billion
The total cost thus ranges from -$4.75 billion to $2.59
billion.
Note
1. Throughout this report, tons (t) are metric; 1 Mt = 1 megaton
= 1 million tons.
References
Davis, S. C., D. B. Shonka, G. J. Anderson-Batiste, and P. S.
Hu. 1989. Transportation Energy Data Book: Edition 10. Report
ORNL-6565 (Edition 10 of ORNL-5198). Prepared for the U.S.
Department of Energy. Oak Ridge, Tenn.: Oak Ridge National
Laboratory.
Institute of Transportation Engineers. 1989. A Toolbox for
Alleviating Traffic Congestion. Washington. D.C.: Institute of
Transportation Engineers.
Pisarski, A. 1987. Commuting in America: A National Report on
Commuting Patterns and Trends. Westport, Connecticut: Eno
Foundation for Transportation.
Pucher, J. 1988. Urban travel behavior as the outcome of public
policy: The example of modal split in Western Europe and North
America. The Journal of American Planners Association
54(4):509–520.
Toruemke, D., and D. Roseman. 1989. Vanpools: Pricing and market
penetration. Transportation Research Record. 122:83–87.
U.S. Department of Transportation. 1989. National Transportation
Statistics. Washington, D.C.: U.S. Department of
Transportation.
U.S. General Accounting Office (GAO). 1989. Traffic Congestion:
Trends, Measures and Effects. Washington, D.C.: U.S. General
Accounting Office.
Wegmann, F. 1989. Cost-effectiveness of private employer
ridesharing programs: An employer's assessment. Transportation
Researh Record 1212:88–100.
Representative terms from entire chapter:
solo driving
