The state plans to create an H-1 Zipper Lane for the afternoon rush hour that may open in 2011, the state Department of Transportation said yesterday.

The existing H-1 Zipper Lane uses a concrete divider to convert two 'ewa-bound lanes into one diamondhead-bound lane during morning rush hour, then restores the 'ewa-bound lanes afterward. Though the idea has been discussed for years, there is no Zipper Lane for heavy 'ewa-bound traffic during afternoon rush hours.

The new PM Zipper Lane would run from Radford Drive, near Aloha Stadium, to the Waiawa Interchange, where the freeway splits into H-1 Wai'anae-bound and H-2 Wahiawa-bound.

Tammy Mori, a DOT spokeswoman, said a consultant has already completed a feasibility study. Bidding for the project, estimated to cost $45 million, would begin by March.

"The project design will take an estimated seven months after a contract is awarded and construction is projected to take a year," Mori said. "Basically, it will take less than two years to design and construct the project ... which puts us at an early 2011 completion date."

To further assist west-bound traffic, a related construction project will begin a short time later, Transportation Director Brennon Morioka said. That would create a fourth west-bound lane of H-1 from the Waiawa Interchange to the Waikele off-ramp using the existing, right-side shoulder lane by the Waikele shopping center, he said.

Eventually, a Zipper Lane or some other contraflow measure to help afternoon west-bound traffic would start at the Nimitz Highway/Ke'ehi Interchange, Morioka said.

Most of the PM Zipper Lane project will be paid for by the federal government, Mori said.

"We are implementing the PM Zipper Lane because we believe the AM Zipper Lane has been a success," Mori said. "We want to continue to offer an incentive to drivers who choose to carpool, as well as help alleviate some of the congestion in the afternoon rush hour."

When Zipper Lane rules changed in July so that only vehicles with at least three people could use the lane, Zipper Lane use dropped by an average of nearly 2,000 vehicles a day during morning rush hours.

Since then, Zipper Lane use has climbed and now averages 2,546 vehicles daily. It is open from 5:30 to 8:30 a.m. on weekdays.

Maeda Timson, chairwoman of the Makakilo/Kapolei/Honokai Hale Neighborhood Board, said she thinks the PM Zipper Lane is a bad idea, as long as the state continues to use three people as the threshold for vehicles in the Zipper Lane.

Much more people would carpool, and the Zipper Lane would be better used, if vehicles with two people were allowed, she said.

"It's unnecessarily causing more traffic," Timson said, adding that she's miffed the department did not take the plan to the neighborhood boards of the affected communities before deciding to proceed. "It's just making congestion worse."