In addition to a $7.8 million effort to shore up the highway around Makapu'u Point, the state is studying alternative routes through the area and will discuss them with the public tomorrow night.

Alternatives include excavating the hillside, putting a cantilevered road over the cliffside's edge and boring a tunnel, said Brennon Morioka, director of the state Department of Transportation.

Estimated costs range from $50 million to more than $200 million.

"If we have to scale back the rock or build a new cantilevered road that hangs out over the cliff then we'd have to shut the road down completely for two to three years," Morioka said. "It would be closed 24 hours a day for three years."

The state is now fixing a retaining wall along Kalaniana'ole Highway at Makapu'u Point and will install netting to catch falling rocks and an "impact fence" higher up the hillside to contain larger boulders. The project should be finished by the end of the year, Morioka said.

This follows a $1.3 million project in 2002 to remove loose rocks and hang a safety net there. It closed the highway for eight hours a day and businesses struggled to survive.

Waimānalo Neighborhood Board chairman Wilson Ho said any closure would be unacceptable because of the effect on businesses and people who travel between Hawai'i Kai and Waimānalo for work.

"The businesses would die, absolutely die" Ho said, adding that the community had requested a tunnel or a cut in the mountain opposite the entrance to Waimānalo Beach Park.

"We thought for the safety of the people, it would be a better option," he said. "We told them the road is sinking (along the cliff) and they needed to do something more permanent."

The road around the lookout is not carved out of the hillside, Ho said. A retaining wall was built in 1928, fill was added and the road built on the fill.

The work being done now is to reinforce the retaining wall and anchor it to the mountain, Morioka said.

Other options are building a shield over the road or continue to maintain the present road, Morioka said.

"This process is supposed to tell us if what we're doing is appropriate for short term and long term or should we be looking at other permanent fixes," he said.