Here is the first draft of guidance for monitoring indicator 9.1.2, as of 18/12/2019. Please send comments to BlackburnA@un.org. 

Country Comments

United States (19/12/2019)

• I don’t understand the comment near the top of page 4 that “tracking transport volumes … can at least indicate whether current infrastructure is providing sufficient capacity.”  Transport volumes can only be a good measure of whether capacity is sufficient when combined with other data, such as the amount of road or rail mileage. 
• A measure of the percent of travel accomplished by sustainable transportation, such as low or no emission vehicles, or a measure of sustainable transportation vehicle sales would be a better fit than passenger or freight volumes with the sustainable development goals.  
• I don’t agree with the first sentence of 4.2: Inland Passengers.   In a country that has a large area, such as the United States, there can be a huge amount of passenger-km by the air mode.  In the United States, the number of domestic passenger-km by air is over 100 times the number of passenger-km by Amtrak (our long distance train system).  At a minimum, replace the word “typically” with “often”.