How your Transportation score is calculated:
Greenhouse gas emissions are calculated here based on a comparative life cycle assessment of each mode of transportation, in kilograms of greenhouse gases per mile travelled (GGE/PMT), which is then converted to kilometers.
This accounts for all GGE from production, distribution, use and disposal of each type of vehicle. Hybrid/motorcycle/scooter scores (not part of the original life cycle study upon which this calculation relies) are estimated based on average fuel consumption rates as compared to gasoline powered sedans, at roughly half the fuel consumption (1). Skytrain scores are only an estimate based on BART GGEs. Trolley buses are reported to rate comparably to Skytrain in terms of GHGs (2).
It is estimated that transportation accounts for 36% of all greenhouse gas emissions in the province, as compared to 11% for all residential and commercial use, and 2% for GHGs attributed to electricity (2). Therefore, any changes we make in our transportation choices can have the most impact. At the time of the development of this app we do not have verifiable GGE ratings for Seabus, so this rate is nominally reported as equivalent to that of an on-peak diesel bus (2).
Actual emissions vary depending on a number of factors, including (A) diesel, gasoline, or articulated trolley buses; (B) using Seabus, Skytrain, or bus; (C) whether buses are used at capacity (peak hours) or during off peak times. Your score represents a weighted average of the following scores, weighted according to Translink’s reported total passenger boardings for the first 6 months of 2011 for each mode (6). Since figures showing the various rates for on- or off-peak and trolley vs diesel buses are not available at this time, the GGE rating for all bus services is averaged among those three modes. Admittedly this is probably an overestimated GGE rating, as off peak ridership should by definition be weighted minimally.
Total Translink Passenger Boardings – January to June 2011 (6)
Bus services 110,196,269
Expo / Millennium Lines 39,832,800
Canada Line 19,185,093
West Coast Express 1,422,204
Diesel bus on peak: 53 GGE/PKT. 37 million=1,961,000,000 GGE/PKT boardings
Diesel bus off peak: 418 GGE/PKT. 37 million=15,466,000,000 GGE/PKT boardings
Articulated trolley bus: 84 GGE/PKT. 37 million=3,108,000,000 GGE/PKT boardings
Skytrain: 84 GGE/PKT. 59 million=4,956,000,000 GGE/PKT boardings
Seabus: 84 GGE/PKT. 3 million=252,000,000 GGE/PKT boardings
Total GGE/PKT boardings=25,743,000,000
Divided by Total Passenger boardings (173 million)
=Weighted Average Transit GGE/PKT: 25.7 billion/173 million= 148.8
Cars, trucks and motorcycles rank among the highest rates of emissions per passenger. The score here is a mean score for cars of various types. Your car or truck may actually emit more (or less) GGEs in its life cycle than this figure indicates. For information on the emissions and fuel economy of your car’s model, see this link.
Weighted automobile GGE/PKTs were calculated based on ICBC licensing statistics, as follows:
Pickup: 384 GGE/PKT. ~900,000 licensed=345,600,000 GGE/PKT
SUV: 277 GGE/PKT. ~900,000 licensed=249,300,000 GGE/PKT
Sedan: 237 GGE/PKT. ~900,000 licensed=213,300,000 GGE/PKT
Hybrid/motorcycle/scooter: 119 GGE/PKT. ~116,000 licensed=13,804,000 GGE/PKT
Total GGE/PKT in the BC population of vehicles: 822,004,000
/Total number of vehicles (=2,816,000)
=Weighted Average GGE/PKT: 292
Bicycles are by far the least carbon intensive form of individual transportation. While some CO2 is produced from the cardiovascular workout you get by doing the act of bicycling, and some CO2 is expended in the manufacture, distribution and disposal of bicycles, they still produce less CO2 than other forms of transport, by a wide margin. Electric bicycles produce roughly the same amount of GGEs in life cycle analyses as conventional bicycles.
Buses (and Seabus):
When and how you use the bus matters. If we are using a diesel or gasoline-powered bus during peak hours, we are responsible for less CO2 emissions than if we ride the same bus with fewer passengers (during off-peak hours), because the amounts of emissions on both trips would be approximately the same, but divided by a different number of passengers. When we use articulated trolley buses (which are electric), we emit a similar amount as when we ride the Skytrain (according to Translink’s emissions reports).
While Skytrain is an energy intensive endeavor to build and maintain, it runs on electricity, which in B.C. Largely comes from hydroelectric dams. Hydroelectric dams account for comparatively little in terms of GHG emissions, but do account for some. In other cities, where electricity is generated via coal or oil plants, emissions from rail transport are understandably higher.
Walking, believe it or not, also produces CO2, but in negligible quantities.
1. The comparison of hybrids and all-gasoline powered vehicles is an estimate based on a comparison of city MPG ratings for a 2012 Prius hybrid and a 2012 Toyota Corrolla.