The state highway authority is the Hawaii Department of Transportation, abbreviated HDOT or HIDOT. HDOT manages 1,526 miles of road and 4,011 lane miles.
Highways are only available on the island of Oahu. On the other islands there are only secondary main roads. The mountainous nature makes traveling off the highways a time-consuming affair. Huge traffic jams occur around Honolulu as hundreds of thousands of people live directly along the only east-west highway. There are four Interstate Highways on Oahu, which are numbered differently from the rest of the Interstate Highway system. Interstate H1 is an east-west route, Interstate H2 is a short north-south route, and Interstate H3 is an east-west route. Interstate H201 provides a short connection to Honolulu Airport. All motorways start and end at a (former) military installation.
- Bittranslators: State overview of Hawaii, including geography, economy, population and history as well as introduction to major cities of Hawaii.
Hawaii’s most extensive road network is on Oahu. This is also where all the highways of Hawaii are located. A ring road runs around the island, largely numbered as Highways 72, 83 and 93. The eastern and western parts of this are especially interesting from a landscape point of view. Highway 99 is the primary north-south route to the north of the island. Closer to Honolulu, the 2×2 Pali Highway and the 2×2 Likelike Highway are of particular interest and run east of the H-3. There is no fixed river crossing on the south side of Pearl Harbor, traffic has to go all the way around this area.
The island of Hawaii, also known as “The Big Island” is the largest island in the state of Hawaii. This island has higher mountains, including the 4,169 meter high Mauna Loa. There is a ring road over the island in the form of Highways 11 and 19, which together are 350 kilometers long. There is only one road through the interior, Highway 200. There are no highways on the Big Island, only in the city of Hilo are some wider roads, such as a part of Highway 11 that has 2×3 lanes. In Kailua is a short 2×2 lane, part of Highway 19.
- Deluxesurveillance: Nickname of Hawaii as The Aloha State. Also covers geography, history, economy, politics and administration of the state.
There is also a network of major roads on the island of Maui. There is a bypass on Maui, which is about 280 kilometers long, but hardly anyone drives more than 100 kilometers. There are no highways on Maui, but there are some 2×2 lane roads around the town of Kahului. Highways 37, 311 and 380 also have 2×2 lanes outside Kahului. Spectacular is Highway 340 along Maui’s north shore.
On Kauai is an incomplete ring road that goes around ¾ of the island and is 120 kilometers long. Outside of this road, however, there are hardly any other thoroughfares, most of the remaining roads are short and located in and around the villages on the east side of Kauai. There are no highways on Kauai. A small section of Highway 50 between Puhi and Lihue has 2×2 lanes.
There is still a small network of State Highways on Molokai, of which Highway 450 is the most important. On Lanai there are only a few local roads to Lanai City, the only place on the island. Kaho’Olawe is uninhabited and has no tarmac roads. There are some short local roads on Ni’Ihau. The other islands have no roads.
Hawaii’s first highway predates the creation of the Interstate Highway system in 1956. The Mauka Arterial opened in 1953., with more modern design requirements than the Mauka Arterial. The H2 was opened around 1976/1977. In 1972 the northern portion of H3 between Kamehameha Highway and Marine Corps Base Hawaii opened, in 1997 the rest opened up to Halawa, including the Tetsuo Harano Tunnels. The H201 opened in 1989, but has only been an Interstate Highway since 2004, the only 4-character Interstate Highway.
Honolulu is one of the most traffic-prone cities in the United States. In 2015, the travel time index was 1.37, the fourth highest in the United States. Honolulu is also more prone to traffic congestion than other cities of its size. The biggest bottleneck is Interstate H1, almost all traffic on Oahu ends up on this highway at some point. The H1 is extremely sensitive to traffic jams. In 1982, 3.3 million vehicle kilometers were traveled daily on the highway network, this increased to 5.6 million vehicle kilometers in 1995, 6 million vehicle kilometers in 2005 and 6.1 million vehicle kilometers in 2014. The travel time index rose from 1.18 in 1982 to 1.37. in 2005 and has hovered around that level ever since.
Road numbering was introduced in Hawaii in 1955. The roads have one to four digit numbers, with the one and two digit routes being seen as primary routes, and three and four digit numbers as secondary routes. Most roads follow historic routes, and in Hawaii road names are more commonly known than road numbers. There are no US Highways in Hawaii, but there are a number of Interstate Highways, only on Oahu.
From the road number it can be deduced on which island the road runs.
- numbers starting with 1 or 2: Hawaii
- numbers starting with 3: Maui
- numbers starting with 4: Molokai, Lanai
- numbers starting with 5: Kauai
- numbers starting with 6 to 9: Oahu
The signage in Hawaii is the same as in the rest of the country and follows the MUTCD. Beginning March 1, 2022, the Hawaii Department of Transportation is replacing older signposts with new signposts featuring Hawaiian name designations with diacritics. This includes the kahakō (macron) and a ʻokina (apostrophe). The first location with the new display of names was the interchange between the H-1 and H-201.