State transportation officials say the diverting of H-1 Freeway traffic to a temporary one-mile bypass in either direction between Kunia and Makakilo won't be a major inconvenience for the tens of thousands of motorists who travel through West O'ahu daily.

Motorists aren't so sure.

The six-month-long temporary bypass, which will affect Wai'anae- and Honolulu-bound traffic, is scheduled to begin this weekend and run through December. State Department of Transportation traffic counts showed a daily average of about 105,800 trips traveled in either direction during 2006.

"We don't expect it to have a major impact on traffic," said Tammy Mori, DOT spokeswoman. "We expect traffic to move pretty smoothly once (drivers) get used to the change."

While some West O'ahu residents have shrugged off the diverted lanes as a necessary evil, some neighbors are skeptical about the DOT's assurances.

Patty Teruya, chairwoman of the Nanakuli-Ma'ili Neighborhood Board, said she is a little worried about how the detours will affect traffic.

"Right now, even, the freeway can't handle the traffic," Teruya said. The ongoing construction has caused the road to curve somewhat and motorists have had some difficulty dealing with that, she said.

"You're going to (see) some brakes, you're going to see a lot of red lights," Teruya said.

Mori urged motorists "to use caution, slow down and be careful" when they first encounter the bypass.

BYPASS SPEED SLOWER

Like the freeway section in the Kunia-Makakilo area, the bypass will be three lanes in each direction, Mori said. What's different is that it will be on a curve and carry a reduced speed limit of 50 mph. The usual speed limit through the Kunia-Makakilo section of H-1 is 60 mph. But motorists have had to deal with a reduced 50-mph limit in the area already in recent months because of other construction related to the bypass, Mori said.

The existing freeway lanes in each direction are about 11.5 feet wide, said DOT site engineer Alex Oshiro. On each side of the bypass, two lanes will be about 11 feet while a third lane will be 12 feet, he said.

The rerouting marks the first time in the half-century history of O'ahu's freeways that an entire section of a freeway has been detoured, Mori said.

But the type of curving involved is not new to the freeway system. For instance, those who travel between Moanalua Freeway and H-1 Freeway at the Middle Street and Aloha Stadium interchanges also need to navigate at slower speeds through curved areas.

BUILDING 2 NEW BRIDGES

The bypass is necessary to allow construction crews to tear down an existing bridge and put up two new ones, one in each direction, that can accommodate the upcoming North-South Road freeway interchange, which isn't expected to open until spring 2010. At that point, it will connect with the North-South Road, which is expected to provide relief for 'Ewa and Kapolei motorists.

The plan calls for: