Are Hawaiis Interstates ever referred to as “I-H-1,” etc.?
Thankfully, no. They’re simply called “H-1,” etc. or “Interstate H-1,” etc. In addition to looking strange with the Hawaii Interstates’ “H-” numbers, the “I-” prefix would be inappropriate because FHWA reserves that for the mainland’s Interstate network, and assigns instead the distinctive “H-” prefix to the separate Hawaii Interstate network. Thus, the FHWA route log refers to “I-4,” “I-5,” etc., but to the Hawaii Interstates as “H-1,” “H-2,” etc., with the “H-” substituted for “I-” as the prefix. Ditto for the “paper” Interstates of Alaska and Puerto Rico, which are respectively “A-1,” etc. and “PRI-1,” etc., with no “I-” (pre-)prefix.
