requiring mileage-based exit numbers on tier 1 highways.

HB 1785 requires all New Hampshire tier 1 highways (excluding I-393) to adopt mileage-based exit numbers that align with federal traffic control standards. This affects drivers traveling on major highways like I-93, I-89, and the Turnpike, as well as the New Hampshire Department of Transportation (NHDOT), which must replace existing exit signage by 2038. The bill mandates using the Federal Highway Administration's manual for exit numbering, based on mileage in NHDOT's system, with implementation beginning as early as fiscal year 2031. Costs will be phased over time, with initial planning starting in 2031 and construction through 2038, funded primarily through federal highway grants.