Tish Acido-Mercado hopes an improved H-1 Zipper Lane will save 10 to 15 minutes on her morning commute into town.

The three-mile H-1 Zipper Lane extension and connection with the Nimitz contraflow lane opens Aug. 15. When it opens, vehicles can use the lane if they carry two or more people; the present minimum is three.

Acido-Mercado, who drives into Honolulu from 'Ewa Beach, said connecting the Zipper Lane and the Nimitz contraflow lane should prevent or limit the time she'll have to sit in bottlenecked traffic near the airport exit.

"When we have our grandson with us, that's when we can use the Zipper Lane," said Acido-Mercado, 58. "It does alleviate us from going through normal traffic. Also going down Nimitz, through the contraflow, it does help."

About 4,000 drivers a day now use the Zipper Lane. Linking the existing Zipper Lane with the Nimitz contraflow lane, now used by about 2,000 drivers daily, will makes for a continuous 15-mile commute.

The extension should provide commuters with relief during morning rush hour, said Rod Haraga, state transportation director. He estimated Zipper Lane commuters will save 15 to 20 minutes of drive time.

The modified Zipper Lane includes an entrance near the Radford Drive overpass for Pearl City and 'Aiea residents.

Haraga said he hoped drivers will get used to merging at the new entrance in time for back-to-school traffic. All public schools, including the UH-Manoa and the community colleges, will be in session by Aug. 23.

'Aiea and Pearl City residents have long requested an entrance.

"My hunch is that it will lead to less traffic in the noncarpool lanes because people with two or more drivers, like myself, can now use that," said Rep. Roy Takumi, D-36th (Pearl City, Palisades), who has pushed for a Zipper Lane entrance for Central O'ahu residents.

Drivers will still be able to exit near the airport, Haraga said, but they also can remain in the Zipper Lane and continue along Nimitz Highway on the contraflow lane until Hilo Hattie's.

The extension wasn't expected to be completed until September, but "we pushed the contractor, and we are able to open it up," Haraga said. "We wanted to get it before the back-to-school jam — that was really critical."

Federal money paid $8 million of the $9 million construction project, and the state covered the rest, he said.

Some commuters want to see the plan work before they estimate how much time they will save.

Angela Lundgren, 28, of Wai'anae, said she commutes to work with friends, and they can sit in traffic for more than an hour in the morning.

"If they connect the Zipper Lane to the contraflow lane, it'll be the same thing, if you ask me," she said.