By rail vs. by sea vs. by inland waterway

Good question! I'm also interested in this, so I'll see what I can find out and get back to you. It's hard to get good data comparing different modes of frieght transport that include both inland waterways and ocean-going vessels, but the little I've seen wouldn't justify such a big differential.LEED Canada has had a mode of transport differential since it's beginning, but it just has 1x for trucks and 3x for all rail and shipping.

Sorry it took so long, but I was finally able to learn where these multipliers came from. This Alternative Compliance Path originated from the LEED International Working Group, and it's based on data from this report: "Transport at a crossroads. TERM 2008: indicators tracking transport and environment in the European Union." The relevant numbers are on page 12, and they are sourced to this German transportation impacts calculator: EcoTransitIT World.I spent a little while trying to see how the Transportation at a Crossroads report got to those numbers, but the EcoTransit methodology is pretty complicated, so it wasn't obvious how to verify them. I'm still curious why they're so different from the numbers used in LEED Canada--perhaps someone who has researched this area will help us sort that out eventually.