I-H-201  Hawaii (link)

Proof! Interstate H-201 is shown on this 1997 AAA map of Hawaii. (From its 1990 inception until July 2004, this freeway was posted only as state route 78.)

4.10 miles [1]; this is the portion of the Moanalua Freeway from I-H-1 near Aiea to I-H-1 heading for Honolulu. Appropriately, its name sounds like water (say it aloud).

I-H-201 is Hawaii's only three-digit interstate, and the nation's only four-character interstate. (In the past, Idaho's I-184 was known briefly as I-180N.) Until July 2004, it was also a "secret" interstate, signposted only as state route 78.

How H-201 came about

H-201 is unique not only in name but in history: its designation arose from a Hawaii DOT (HDOT) intent to correct a "nonconforming condition" at the eastern H-1 / HI 78 junction. At this point, three lanes of mainline road serve HI 78, which should be a right-hand exit; and two lanes of right-hand exit serve H-1, which should be the mainline. (See diagram and details by Oscar Voss.) Motorists not expecting this could miss the turn and no longer be on an interstate highway. HDOT's plan was to designate HI 78 as an interstate.

You might ask why the interchange was built this way. The answer: the airport segment of H-1 was the last to open, and was connected via ramps to the existing H-1 / HI 78 mainline. Here are the approximate opening dates of each freeway leg leading from the interchange:

• West: Moanalua Freeway, HI 78 WB; most of it opened in early 1960s, and upgraded in the 1980s
• East: Lunalilo Freeway, H-1 EB; completed in mid-1960s to mid-1970s
• South: Queen Liliuokalani Freeway, H-1 WB; completed in 1986

Rather than tear up the east-west mainline, the south leg was connected by two ramps, creating the left exit onto HI 78 from H-1 westbound.

The addition of HI 78 to the interstate highway system was approved by the FHWA on Nov. 1, 1989. [9] Before we get to the number selection, which occurred later, consider two things:

• The same procedure to fix left exits on I-84 in Connecticut would result in 13 new interstates
• The deficient condition in Hawaii still remained, it violated interstate standards, and the new (non-chargeable) designation obligated no federal funds at all to fix it.

We need a number; or, "H-1B" has political overtones

So... how would you number a loop of Interstate H-1? (By the way, Hawaii interstate numbers officially have a hyphen after the "H", even if some signs omit it. [5])

On June 2, 1990, HDOT requested the number "I-H-1A," to which AASHTO's response was "Action Withheld." (Interstates with letter suffixes, fairly common 30 years ago, are discouraged today.)

On December 7, 1990, HDOT went forward with plan B: proposing "I-H-101." AASHTO thought better of this suggestion, but because the road met H-1 at both ends, it approved the highway instead as I-H-201. [3]

What about the "secret" designation mentioned earlier?

Not only did the new H-201 number neither fix the interchange nor help in funding, for over a decade HDOT decided it was better not to signpost it. Three reasons were cited for this:

• Conventional wisdom: interstate route markers cannot legibly contain four characters (H, 2, 0, 1)
• HDOT encourages motorists to use the newer, better H-1 route
• The highway was already known as highway 78, or the Moanalua Freeway, and adding another designation was not constructive [4]
• Motorists might confuse H-201 with nearby H-2 [10]

For 14 years, the H-201 designation remained "secret": in the federal route log, and on some maps, but not signposted.

C. C. Slater wrote: "I don't like the [renumbering], logical though it is. Heck, I grew up riding up and down that road -- seeing the big elevated junction at Kam Highway for the first time was what got me started in roads anyway. The [SR 78] designation has sort of a sentimental value!" [2]

In mid-2004, no longer secret

However, in July 2004, as part of a road rehabilitation project, HDOT upgraded the guide signs and added the H-201 designation. [7] The "new interstate in town" was a surprise to some motorists. [8]

Why was H-201 signed at this point, after 14 years? HDOT spokesman Scott Ishikawa (no relation) told the Honolulu Star-Bulletin that since they were erecting new signs, they were required to use the new H-201 designation instead of Route 78. [10]. (However, there are at this writing 13 unsigned 3di's.)

Oh well. After a while it just seems really mainland to worry about such things.

State highway H201? No, that's an error

Some 2004 atlases show H-201 as state route H201, which is incorrect; the route's designation hasn't changed. A typo in the Hawaii DOT's website, which uses the state designation, could have misled some mapmakers. [6]

See also:

• Hawaii Road Signs (Oscar Voss)
• H-201 exit list (Oscar Voss)
• What's the story with H-201? (Oscar Voss, Hawaii Highways FAQ)
• Roads and Highways under State Jurisdiction, Oahu (Hawaii DOT)
• 3di table (includes list of unsigned 3di's)

Sources

1. Route Log and Finder List - Interstate Highways, FHWA, Oct. 31, 2002.
2. C. C. Slater. "Ack! Ack! Ack! Interstate H201?!?" Personal email, Sept. 6, 1997.
3. AASHTO Route Numbering Committee notes, thanks to R. V. Droz
4. Voss, Oscar. "Supplement to H201 listing on your 3di site." Personal email, Jan. 7, 2001.
5. Voss, Oscar. "Another nit-pick on H201 page." Personal email, Jan. 7, 2001.
6. Voss, Oscar. "Interstate H-201 update." Online posting, misc.transport.road, Sept. 17, 2003.
7. Voss, Oscar. "The secret's out on Hawaii's Interstate H-201." Online posting, misc.transport.road, July 27, 2004.
8. "Moanalua is actually part of interstate." Honolulu Star-Bulletin, July 27, 2004. (Thanks to Oscar Voss)
9. Voss, Oscar. "Hawaii Highways FAQ page 4." http://www.hawaiihighways.com/FAQs-page4.htm#H-201 (29 July 2004)
10. "New freeway designation demystified." Honolulu Star-Bulletin, Aug. 30, 2004. (Thanks to Oscar Voss)