A major point of the interstate system is to connect all parts of the nation in the most direct and efficient way possible. Over the last near century, this has been accomplished, even in the states that aren’t in the contiguous United States. To differentiate from the connected states, Hawaii’s interstates are prefaced with an H instead of an I and their number system is much more simplified, ranging just from 1 through 3. This simplification of Hawaii’s interstate system is far from representative of their interstates. In fact, H-3 is the most expensive interstate project in the history of the interstate system, involving some of the most complex designs, unique obstacles, and award-winning press events.
Unlike the connected United States, “H” does not stand for “highway,” but literally for the state of “Hawaii.” These interstates (criticized for not being highways within the states) still have to follow the same interstate standards, with the design focused on handling high volumes of traffic safety. H-1 is the longest at 28.16 miles (43.71km) running through Honolulu on the island of Oahu, and is the southernmost and westernmost interstate of the entire US. East of Honolulu’s Middle St., the interstate is known as Lunalilo Freeway after the former Hawaiian King, and the western side is called the Queen Lili-oukalani Freeway after the queen. This interstate was authorized a year after being admitted as a state in 1959, joining with already existing corridors and completing the “new” areas of construction by 1963.
Only 8mi long, H-2 was built to connect H-1 to the north shore of the island. This interstate also connects Pearl Harbor Naval Base and Hickam Air Force Base to Wheeler Air Force Base. Another name for this interstate is the Veterans Memorial Freeway. After construction began in 1971, an interesting discovery was unearthed: the ruins of Cabrini Chapel. This was a a small church built by Italian prisoners of war housed at Sand Island from 1944 to 1945. The interstate was completed and open to the public in 1977.
Then came plans for H-3—a project that required decades, multiple teams from a range of fields, and has been estimated to be the most expensive interstate highway on a cost-per-mile basis, ranging from $80 million to $1.3 billion a mile. This was the biggest construction and public works project Hawaii has ever undertaken, involving 20 separate contracts, a “cut and cover” tunnel, multiple viaducts, the Trans-Koolau twin tunnels, and more. Hawaii’s Department of Transportation hired experts in the fields of botany, zoology, archaeology, Hawaiian culture, and water, noise and air to conduct and validate studies that would become integral to the planning process. For our purposes, we’ll focus on the construction aspect of this highway.
The first feat was the construction of the Hospital Rock Tunnel, a 690-ft “cut and cover” with separate inbound and outbound tunnels. This type of tunnel cuts through the mountain completely, leaving the top open to the daylight. The tunnel itself is constructed and then the cover is completed. The Hospital Rock Tunnels were approximately $18 million to complete.
A much more difficult project was the completion of the Trans-Koolau Tunnels, running through the Koolau Mountains. To begin, a 14-foot-wide exploratory tunnel was bored for engineers to gather geological information, prior to designing the main tunnel. Though this cost $12 million, it saved HDOT much more by allowing engineers to see future obstacles and also reduced the expense of the finished project.
The construction involved two contracts, one for $89 million and another for $108 million. Tunnelers sprayed a mixture of cement, sand, and water to bore through and bolted rock for temporary support for the first 300 feet into the Halawa side, but then the rest was tunneled through good rock. Rain water needed to be filtered by creating a waterproof seal to avoid any drips. Then the focus was ventilation, which was accomplished by adding a false concrete ceiling throughout the entire length, separated into two sections with a concrete divider. One side removed exhaust air and the other distributed fresh air using large fans. (This process was discussed more deeply in our blog about the Eisenhower Tunnel in Colorado, if you’re interested.)
Finally, there are the impressive Windward Viaducts: one-mile-long structures that connect the Trans-Koolau Tunnels to the Hospital Rock Tunnel. These viaducts consist of 23 sets of piers ranging from 12 to 160 feet in height, and their structure makes them appear arched. The Department of Transportation actually goes into extreme detail over how these were made, from the width and length of each shaft pile, to the uniquely designed steel erection truss system. However, since they’ve said it best, we’ll go ahead and link that here if you’d like to know more.
Once these aspects of construction were completed, there were still a few more setbacks. There was the question of what to do with the United States Coast Guard’s (USCG) Omega Station, once critical for worldwide navigation, now made obsolete with the creation of GPS. These bombproof, 3-meter thick reinforced concrete walls with six cable antennae 600 meters above the valley were too close to the desired highway; plus, they emitted radiation, which posed a hazard. While the original solution was to install a Faraday Shield to protect anyone from the radiation, this was thankfully unneeded when the station closed in 1997, in time to have the antennae dismantled before H3’s opening.
Before H-3 officially opened, HDOT ran a test to see how the general public reacted to the new interstate. They did this by offering four open houses ran by volunteers and taking people on bus rides to showcase the views and state-of-the-art tunnel technology. Without a budget, HDOT earned money by selling merchandise, concessions, and tickets to the event. This proved to be a wild success, as tickets were sold out prior to every open house, with over 30,000 attendees that experienced the 6.5k bus ride and 1.5k walk through the tunnel and over the viaduct. This was so successful that HDOT won an award from the American Association of State Highway and Transportation Officials for the best public relations event in the under-$50,000 category.
(Side note: HDOT decided to do a similar event the following year but instead hosted a 10k “fun run” on Mother’s Day. Over 17,000 people from around the world participated, and samples of the H-3 tunnel tiles were adapted into Mother’s Day souvenirs.)
After 37 years and at immense financial cost, H-3 was ready to open. The Hawaii Department of Transportation held an invitation-only event, shuttling in guests to the official event. The Marine Corps band played as people settled in, and promptly at 11am, the festivities began. First was the Oli, a Hawaiian welcoming ceremony and in this case, a cleansing ritual performed by the Nation of Ku. This group had fought the interstate for years and asked to perform the ceremony to make peace with the interstate and cleanse any curses that may befall the natives. Afterward, there were several speeches from major contributors to the completion of the highway. The closing ceremony was the untying the Maile Lei — made from a Hawaii-local flower called the Maile that is never cut, but tied when an object has not yet come to life. Instead of a ribbon-cutting, the Maile Lei was untied to signify the object “coming to life.”
This nearly four-decade-long project is one of the most complex Hawaii has ever accomplished, involving technology, experts in diverse fields, and dedicated consideration for the culture, the land, the wildlife, and the locals. H-3 is also considered on of the most beautiful scenic interstates ever constructed. If you find yourself on that island, remember that Interstate Signways made the signs that marked the way!
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