Interstate H-201 is a 4.10 mile auxiliary spur of Interstate H-1 located on the Island of O'ahu in the State of Hawaii. Interstate H-201 westbound begins near downtown Honolulu at Interstate H-1 and jogs back to it at Aiea. Interstate H-201 is known as the Moanalua Freeway and was originally constructed as Hawaii Route 78.
Part 1; the history of Interstate H-201 and the Moanalua Freeway
The corridor of Interstate H-201 is tied historically to Moanalua Road which skirted the namesake Moanlau Valley. Moanalua Road was constructed during the 19th Century and originally connected from King Street in Honolulu westward to Aiea. Moanalua Road was paved in macadam circa 1899 which greatly enhanced overland travel. The Moanalua Road can be seen on the 1899 J.T. Taylor map of O'ahu listed as the "Government Road" through the Moanlau Military Reservation.
The Hawaiian Territorial government began construction of a four lane expansion of HI 103/Moanalua Road following the opening of the Triple Army Medical Center in 1948. The full scope of the expansion project would reduce the number of curves on Moanalua Road by 75% and was planned to connect with the Mauka Arterial (now Interstate H-1) in Honolulu. The westernmost 2.7 miles of the expanded Moanalua Road opened to traffic on April 28th, 1954.
On April 6th, 1988 the Honolulu Division Administrator of the Hawaii Department of Transportation submitted a request to the Federal Highway Administration to add entirety of HI 78 and the Moanalua Freeway to the Interstate System as Interstate H-1A. On November 1st, 1989 The Federal Highway Administration informed the Hawaii Department of Transportation that HI 78/Moanalua Freeway was approved to be added to the Interstate System as Interstate H-1A. The Federal Highway Administration did note that the Middle Street Interchange did not conform to Interstate standards. The Federal Highway Administration further noted the Hawaii Department of Transportation would need to petition the American Association of State Highway and Transportation ("AASHTO") Route Numbering Committee to approve the designation of Interstate H-1A.
On May 18th, 1990 the Hawaii Department of Transportation submitted an application to the AASHTO for Interstate H-1A to be designated over HI 78/Moanalua Freeway.
On June 14th, 1990 the AASTHO informed the Hawaii Department of Transportation that the consideration of the approval of the designation of Interstate H-1A was withheld pending further review.
The Federal Highway Administration in a letter to the AASHTO dated June 18th, 1990 noted that it was aware the latter was no longer approving suffixed US Routes and Interstates. The Federal Highway Administration went onto add it would ask the Hawaii Department of Transportation to seek a three digit auxiliary designation for the Moanalua Freeway given it looped to/from Interstate H-1.
On October 24th, 1990 the Hawaii Department of Transportation petitioned to the AASHTO assigned the Moanalua Freeway as Intestate H-101. On December 8th, 1990 the AASHTO Executive Committee approved the designation of Interstate H-201 on the Moanalua Freeway. In the AASHTO's response to the Hawaii Department of Transportation noted it selected H-201 given the Moanalua Freeway was a loop of Interstate H-1 and thusly an even digit auxiliary designation was appropriate. Note; odd three digit Interstate numbers are intended to denote auxiliary spur Intestates.
The designation of Interstate H-201 was not signed on the Moanalua Freeway for numerous years and the existing HI 78 signage remained in place. The Hawaii Department of Transportation over years noted several concerns over signing Interstate H-201: