Interstate H-1 was first authorized as a result of the Statehood Act of 1960.1 A portion of the freeway was completed in 1959 between Punahou Street (Exit 23) and King Street (Exit 25A). It was signed as Hawaii 72. A short extension followed in 1960 from Punahou Street west to Ke’eaumoku Street.

Interstate H1 signs were posted by 1967 along side Hawaii 72 and the Lunalilo Freeway. It was open from Kunia Road (Exit 5) to Kamehameha Highway (Exits 8A/B), from the east end of the Moanalua Freeway (I-H201) to Pele Street (Exit 21B), from King Street to Koko Head Avenue (Exit 26A). Completion of the route occurred in 1986 with the opening between Nimitz Highway (Exit 18A) and Middle Street. See the Interstate H1 guide on AARoads for a more detailed time line.

Freeway signs that showcase the name of Interstate H-1, the Queen Liliuokalani Freeway, were erected in 2002. The Queen Liliuokalani Freeway signs stand eastbound at Exit 1 and westbound after Exit 19. There are no similar name signs for the rest of H-1, which is called the Lunalilo Freeway.3

Some improvements made to Interstate H1 include adding auxiliary lanes, widening, and earthquake retrofitting. The Pearl City and Waimalu viaduct bridge deck was replaced by April 16, 2014. This work preceded restriping of the Halawa Interchange to the Pearl City off-ramp to add a shoulder lane during the evening peak hours and widening of I-H1 from the Pearl City ramps to the Waimalu viaduct. Widening also expands I-H1 westbound from I-H2 to Waikele, capping off expansion overall between Aiea to Waikele.4

Proposed Interstate H-4

Interstate H-4 was an idea once proposed for the city of Honolulu in the late 1960s. Interstate H-4 was to provide traffic relief for the congested Interstate H-1 through the downtown area of the capital city. From the west I-H4 was to begin at I-H1/Exit 18 interchange with Hawaii 92. Turning southeasterly, the freeway was to follow the Honolulu waterfront to a point somewhere between Atkinson Drive and Waikiki. At that location, Interstate H-4 was proposed to turn northeast to the Kapiolani interchange (Exit 25B) along Interstate H-1. As one can surmise, the idea of a freeway along the waterfront through Downtown was wildly unpopular and thus never realized.2