When one truck makes a round with several pickups and drops, should its emissions be split by distance driven or by shortest distance, in the Greenhouse Gas Protocol example?

Question

Accepted Answer

In the Greenhouse Gas (GHG) Protocol's delivery round example, 31.5 kilograms of carbon dioxide (CO2) are split three ways. By driven tonne-kilometres shipment 3 gets 12.3 kilograms; by shortest theoretical distance it gets 6.43. The guide calls the second method a fair allocation. A truck leaves the home station A with shipment 1, 24 tonnes for customer B, 10 kilometres away. At B shipment 1 is unloaded, and shipments 2 and 3, 10 tonnes each, are picked up. Shipment 2 goes to customer C, 15 kilometres from B. Shipment 3 goes back to A, with C to A being 10 kilometres. The guide had mass, distance and mode but no fuel record, so it used the distance-based method and arrived at 31.5 kilograms of CO2 for the whole round. Each shipment's weight times the distance it rode the truck, then each one's share of the total. Shipment 1: 24 x 10 = 240. Shipment 2: 10 x 15 = 150. Shipment 3 rides from B past C to A, 15 + 10 = 25 kilometres, so 250. Total 640, or 0.049 kilograms of CO2 per tonne-kilometre. The shares are 11.8, 7.4 and 12.3 kilograms, which add to 31.5. The guide notes that shipment 2, which causes the longest leg of 15 kilometres, gets the least, and shipment 3 is punished for travelling together with shipment 2 through C. Each shipment's weight times the shortest distance between its own origin and destination, also called the great circle distance. Shipment 1: 240. Shipment 2: 150. Shipment 3: 10 x 10 = 100. Total 490, or 0.064 kilograms per tonne-kilometre. The shares are 15.43, 9.64 and 6.43 kilograms, adding to 31.5. The guide says this is a fair method because each shipment's share rests only on its own characteristics, and that the actual driven distance is of no relevance to the customer. The guide's text picks shipment 3 up at B, which gives the 250 driven tonne-kilometres, but its diagram labels C as the origin of shipment 3. The printed figures follow the text. The shortest distance for shipment 3 is 10 kilometres whether you measure from B or from C, so the 100 tonne-kilometres of option 2 holds under either label. The part-load page here says to use the distance a consignment actually travelled. That is option 1, and the guide's example shows how it can overcharge a shipment that rides along a detour. The page on actual and shortest distance says to use the shortest feasible distance when you apply a carrier's intensity built to International Organization for Standardization standard 14083, and actual distance when you apply a generic per tonne-kilometre factor. Pick one basis for every shipment and say which.

When one truck makes a round with several pickups and drops, should its emissions be split by distance driven or by shortest distance, in the Greenhouse Gas Protocol example?

The round in the guide

Option 1: driven tonne-kilometres

Option 2: shortest theoretical distance

Where the example disagrees with itself, and with a page here

The same 31.5 kilograms, two splits (the guide's figures)

What Senseible does here