Ask the Mayor: Why are the Speed Limits Different on Haleakalā Highway?

File photo by Wendy Osher.

Ask the Mayor

Mayor Alan Arakawa answers some of the most-asked questions submitted to his office staff.

Aloha Mayor: 

Q: I was curious as to why the speed limit going up Haleakalā Highway is 55 mph all the way up to Haliʻimaile and going down it is 45 mph?

I completely understand the crossroads in the cane fields, but those roads are rarely used. A lot of locals around Maui say it is to keep the auto shops in business, due to excessive brake usage and to keep law enforcement busy. Some, former law enforcement say the county does not want to pay to have the signs changed–same with Mokulele as well.

Myself and others would like to know the reasoning behind it please.

Thank you for your time, sir.

A: Haleakalā Highway is a state highway and according to the state DOT, the downhill 45 mph speed limit is set to ensure highway safety. Vehicles traveling at a higher rate of speed with downhill momentum have less reaction time and require far greater stopping distances in the event of an emergency stop versus vehicles traveling up the slope. As speed increases for vehicles traveling downhill, the severity of a head-on collision or impact with a static object is increased as well, reducing survivability.

This stretch of Haleakalā Highway, from Makani Drive to Keahua Road, drops in elevation from 1,550 to 590 feet in only 3.6 miles, during which there are three signalized intersections, a shoulder used by bicyclists, a deer crossing and eight truck crossings that are still used by heavy commercial vehicles. Past the Keahua Road intersection where the downhill slope is not as steep, the speed limit increases to 55 mph. Motorists are asked to drive responsibly and to follow the posted speed limits to ensure that everyone on our roads stays safe.

Want to Ask the Mayor?

Submit your questions about County of Maui programs, services, operations or policies to Mayor Alan Arakawa via email at [email protected], by phone at 270-7855 or by mail to 200 S. High St., 9th Floor, Wailuku, HI 96793. Questions submitted will be considered for inclusion in the Ask the Mayor column.