Interstate H-3 is an intrastate interstate highway located on the island of O'ahu in the state of Hawai'i, United States. Despite the number, signage is that of an east-west highway, although most residents consider the route to run north-south. Its western terminus is at an intersection with Interstate H-1 at Halawa near Pearl Harbor. Its eastern end is at the main gate for Marine Corps Base Hawaii. This route satisfies the national defense purpose of connecting the Marine Corps base (MCBH) with the U.S. Navy port at Pearl Harbor off Interstate H-1.


Interstate H-3 viaduct in Halawa Valley
looking towards the Ko'olau crest

Table of contents
1 Number of Miles
2 Towns Along the Route
3 Intersections with other Interstates
4 Spur Routes
5 Notes

Number of Miles

Total: 16

Towns Along the Route

Halawa, Kāne'ohe, Kailua, Marine Corps Base Hawaii.

Intersections with other Interstates

Spur Routes

None

Notes

This road is an engineering wonder, and perhaps the most expensive (on a cost per mile basis) of any Interstate constructed. It crosses the Ko'olau mountain along a viaduct and through a long tunnel. For many years, the completion of this highway was uncertain, as it runs through culturally and environmentally sensitive areas and some park lands were used. But now, this is a beautiful freeway running through a tropical forest and over the rugged spine of windward O'ahu.


Interstate H-3 viaduct in Ha'ikū Valley
An interesting story relates to the elevated section passing through Ha'ikū Valley (see photograph at right). In this valley (the most scenic section of H-3) the viaduct passed beneath the antenna of a
U.S. Coast Guard radio transmission facility. It was thought that the energy field from the antenna could interfere with heart pace-makers — a potential detriment to drivers and passengers on the roadway. A giant metal cage was designed to surround the roadway through the valley. Before H-3 was opened, the Coast Guard closed their transmitting facility, obviating the need for the cage. Although the full cage was never built, buried within the roadway was the bottom of the cage. HDOT decided to remove this steel mesh (at considerable expense) prior to opening of the freeway to minimize inconvenience to the motoring public at some later time.