"It's going to be inconvenient, to say the least," said George Okuda, who uses the tunnel every day as part of his commute between Kane'ohe and Manoa. "We knew it was coming, but now that it's here we'll find out how bad it's going to be."

The tunnel closing is a necessary last step in a $13.8 million project to improve traffic safety along the Likelike Highway corridor used by some 30,000 motorists a day, officials said.

During the next month, workers will tear out the aging, rutted concrete floor of the Kane'ohe-bound bore of the tunnel and replace it with a new grooved concrete surface. Then, after a break in August, the process will be repeated in reverse as the Honolulu-bound tunnel is shut down for 30 days of repair and rejuvenation.

When the whole project is done sometime in October, a trip through the tunnels should be drier, brighter and safer, officials said.

"We don't want any more of the 15-car pile-ups like the one we had inside the tunnel last year," said Transportation Department spokesman Scott Ishikawa.

Fred Raymond, left, and Eddie Bright of A-1 Construction apply 4-inch-square tiles to the walls of the 50-year-old Wilson Tunnel. Deborah Booker • The Honolulu Advertiser

Almost from the first times in the early 1940s when officials proposed building a cross-Ko'olau tunnel to accommodate increasing urban and residential pressures on O'ahu, the project was filled with financial, political and practical pitfalls.

Political fortunes rose and fell as city and state leaders bickered and squabbled over the right route. Construction companies prospered and went bankrupt as the work ensued. At least six men lost their lives in the building of the tunnels.

And by the time the first bore of the city-sponsored Wilson Tunnels (named for three-time Honolulu Mayor Johnny Wilson, a big supporter) was finally opened to traffic in 1958, the slow deterioration of the tunnels had begun.

"The once shiny white concrete walls are dirt brown and stained from water seepage," said one newspaper report from April 1960.

Since then:

• The original concrete floor, hard and smooth, soon began to crumble and rut, so much so that up close today it looks like a pock-marked crater impact zone, almost a half-inch below its original level.

• The walls, despite regular cleanings, are dim, dingy and water-stained, filled with the exhaust grime from the more than 1.1 million vehicles that pass through the 14-foot-high, 2,800-foot tunnels each year. Cracks in the walls, although not dangerous, can be seen almost everywhere.

Put it all together, DOT officials say, and you have the need for an overhaul. Just like a solidly built home that needs an updating every so often, the tunnels will get fresh flooring and wall coverings, plus a waterproofing job designed to last well into the future.

To reach the point of the tunnel closing, dozens of workers have been toiling through the night for more than four months, often hidden from view of passing motorists.

"The first thing we did was clean the air plenum area above the length of the tunnels," said Terrence Tadaki, the civil engineer in the DOT highways division.

Pictures of the air shaft before the cleaning make it look more like something out of the Ploiocene Epock than a man-made structure. That's because it is hollowed out from the porous basaltic rock formed in what is known geologically as the Ice Age and modified ever since by the slow dripping of water through the mountain cracks.

Although city officials contracted for work to deal with leaking water in the tunnels in 1976, 1977 and 1979, problems continued, water continued to fall onto the roof of the tunnel and eventually made its way onto the roadway. Now, a polyurethane coating on the arched ceiling of the air shaft will direct water to existing downspouts and rain gutters inside the tunnel.

With the walls dry and cracks filled in, work began last month on the most dramatic part of the tunnel transformation, lining the tunnel walls with more than 1 million tiles in three shades of green.

Working through the night as one bore of the tunnel is closed, dozens of workers put up the 4-inch-square tiles in a rapid-fire progression, using a quarter-inch rope as a spacer and covering a standard bathroom-sized section of wall in about 15 minutes. From bottom to top, the tile colors change from dark to light in an intricate, computer-designed pattern meant to keep drivers' eyes on the road, not the side of the wall.

"It makes a great difference in how bright the tunnel appears to a driver," Ishikawa said.

The final phase of the work involves replacing the half-century-old concrete. That's the part of the project that necessitates closing the tunnels for 30 days at a time, Tadaki said.

Starting today, crews will begin sawing the concrete pieces into manageable-sized chunks, have them picked up with a front-end loader and hauled away to an approved landfill site, he said.

Then a new floor will be put down: first 6 inches of a compacted sub-base soil, then 6 inches of a permeable gravel base and finally 10› inches of concrete — 4,600 cubic yards in all, or enough to build several hundred large backyard swimming pools on O'ahu.

Windward motorists say they understand the need for the tunnel closing and don't expect to be traumatized by the work.

"We'll just play it by ear and make some adjustments as we go along," said Becky Tyksinski, a Kane'ohe travel agent who frequently uses the tunnels in her daily travels. "Hopefully, the inconvenience will be worth it. The end result should be good, that's for sure."