Japanese to English Science Environment & Ecology

The document in question addresses the amount of carbon produced by a variety of human activities. 一式 appears in a table as a unit of measurement for modes of transportation, specifically motor vehicles and mass transit (i.e., train/subway). Other units of measure are 人 and 回, which obviously refers to number of passengers and number of trips. I can’t figure out what 一式 refers to here, however, unless it is the number of modes of transportation (vehicles, trains) themselves. It seems like 本 for trains and 台 for motor vehicles would be more likely however. I am wondering if this might not mean something like “fleet” as it appears for each of taxi, rail, passenger vehicle, van, mini-bus, micro-bus and two-ton truck.

Any suggestions sincerely appreciated.