Daniel Convissor's Website

Pollution: Facts and Figures

Chicago Ill.: Cost effectiveness of different strategies to reduce hydrocarbon
emissions compared: 

     Secure bike parking at rail stations:   $311 per ton
     Commuter rail car-pool matching:      $3,937 per ton
     Express park and ride services:      $96,415 per ton
     Feeder bus services to stations:    $214,959 per ton

As of January 1, 1985, air pollution emissions factors per mile for the
average vehicle in the US include:

      3.33 grams volatile organic compounds       (hydrocarbons)
     27.52 grams Carbon monoxide
      2.0 grams Nitrogen oxides

But, for trips of two miles or less, 100% cold start on an average 75 degree
day those same figures are:

       5.7 grams HC   up 73%
      57.52 grams CO -- up 109%
       2.52 grams NOx   up 26%

Cold starts and the lower average speeds associated with short distance car
travel bear a heavy responsibility for pollution, and these are precisely the
journeys that could easily made by bicycle.

[63% of all trips in the US are 5 miles or less -- USDOT]

AVERAGE AUTO MILES TRAVELED IN AN URBAN AREA PROJECTED TO 1980

Average Speed Category (mph)     Annual Miles                                 

      Traveled

5                                 26,000
10                                65,000
15                               320,000
20                               300,000
25                               200,000
50                               310,000

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AVERAGE CO EMISSIONS FOR LIGHT DUTY PASSENGER VEHICLES IN AN URBAN AREA
PROJECTED TO 1980

Average Speed Category (mph)    CO Emissions (grams/mile)

5                               140
10                              100
15                               70
20                               55
25                               45
50                               25

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RELATIVE FUEL ECONOMY AND MEAN TRIP LENGTH

Mean Trip Length       Relative Fuel Economy

1/4 mi.                .1
1                      .25
3                      .45
4                      .55
5                      .60
6                      .65

Trip Length Distribution of 
Existing Midtown Bicycle Trips (Table B-4):

Trip Length Range               Percent of Trips of This Length
(miles)                          Each           Cumulative

0 to 1                           3.3              3.3
1 to 2                          16.7             20.0
2 to 3                          28.0             48.0
3 to 4                          40.0             88.0
4 to 5                           8.0             96.0
greater than 5                   4.0            100.0

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Potential Daily Bicycle Work Trips by Previous Mode (Table C-2):

Previous Mode            Potential Bike Work Trips

Auto driver                    950
Taxi                         5,600
Subway                      20,300
Bus                         32,400

total                       59,250


[If there were bikeways separated from motor vehicle traffic and sufficient
bicycle parking. Their estimate conservatively provides that all switched
trips would be under 2 miles. --dc]

125,000 Btu/gal. of gas
-----------------------     =   1136 mi/gal for bicycle
110 Btu/mi. to ride bike


125,000 Btu/gal. of gas
-------------------------   =  250 mi/gal for walking
500 Btu/mi. to walk
 
References:
energy content of gas -- Tri-State Planning Commission bike energy use --
Hirst, E. walking energy use -- Dougherty, N. and Lawrence, W.

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Energy Consumption of Various Transportation Modes (Btu/pasgr.mi.)

Mode       Full Capacity             Present Occupancy

Auto          1,635                      6,000
Rail          1,000                      4,250
Subway          750                      3,150
Bus             650                      2,500
Walk            500                        500
Bicycle         110                        110

reference:
motorized data -- Tri-State Planning Commission, Regional Propulsion
Efficiency of Tri-State Ground Modes of Passenger Transportation,
March, 1975.

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Estimate Impacts of an Auto to Bicycle Mode Shift of One Percent of NYC
Traffic [on local roads and arterial] (Table 4-2):

Factor   Annual VMT        Savings                  Total 
          Reduction          per mi.              Savings
 
Fuel     38,706,570        .07 gal          2,709,000 gal
CO       38,706,570      41.5 grams     1,606,000,000 gr
HC       38,706,570       4.2 grams       163,000,000 gr
NOx      38,706,570       3.8 grams       147,000,000 gr 
 
[these figures are underestimated due to not factoring in cold starts on these
shorter trips, which yields lower gas mileage and more pollution per mile --
dc]

--Bicycle Transportation for Energy Conservation, a report of the Secretary of Transportation to the President and the Congress, April 1980.