Greenhouse Gases (GHGs) are produced by the burning of fossil fuels, like the gasoline in your car, and contribute to global warming. By riding BART, riders can cut down of GHGs they emit when comparing to driving in units of pounds of Carbon Dioxide (CO2) equivalents.
Here are the notes on the formula you can use to calculate the GHG savings generated by your BART trip:
Carbon Calculator Notes
Formula: GHG Savings = [(Road Distance/MPG) * Gas Emissions] - [BART Emissions * Track Distance]
Track Distance = BART track distance between stations in miles. (Source: BART Financial Planning)
Road Distance = Road distance between stations in miles. (Source: Galilee Enterprise using Freeway 2009 software)
MPG = 21.6 miles per gallon. The miles per gallon (MPG) estimate is based on fuel economy of the light duty passenger vehicle fleet as a whole including both new and existing vehicles (Source: US Environmental Protection Agency Greenhouse Gas Emissions from a Typical Passenger Vehicle, May 2014, Page 2, https://nepis.epa.gov/Exe/ZyPDF.cgi?Dockey=P100LQ99.pdf)
Gas Emissions = 19.62 lbs CO2 equivalents / gallon of gas. (Source: The Climate Registry, General Reporting Protocol, 2015 Default Emission Factors, Tables 13.1 and 13.9. https://www.theclimateregistry.org/wp-content/uploads/2016/03/2015-TCR-Default-EFs.pdf)
BART Emissions = 0.204 lbs CO2 equivalents / BART passenger mile. Based on 2013 Annual Passenger Miles = 1,649,251,188 and annual BART emissions = 152,979 metric tons of CO2 equivalents. (Source: BART 2013 Greenhouse Gas Inventory)
Download the spreadsheet (101k .xlsx)