Each mode of transportation generates an estimated amount of CO2 in pounds per mile traveled. The following estimates are based on national averages from the Federal Transit Administration:
- Bus: 0.64 lbs
- Train: 0.45 lbs
- Trolley: 0.36 lbs
- Carpooling (2+ passengers per vehicle): 0.43 lbs
- Single-occupancy vehicle: .85 lbs
- Walking, Bicycling, or other non-motorized: 0.0 lbs
For each commute trip, CO2 estimates are multiplied by the number of miles traveled. The amount of CO2 generated from traveling alone is subtracted from the amount of CO2 generated by using the alternative mode.
Example calculation for carpooling 10 miles to work = (.43 lbs x 10= 4.3 lbs) – (.85 x 10 = 8.5 lbs) = 4.2 lbs of CO2 saved
Non-motorized modes, such as walking or bicycling, produce 0 lbs of CO2; therefore 0.82 lbs of CO2 (= 1 mile driving alone) is saved for each mile commuted by non-motorized modes.