The driver of a van that crashed into and toppled a 69-foot marine navigation tower fell asleep at the wheel early Sunday evening, police said.

A replacement for the Kewalo Basin Entrance Rear Range Light tower will cost $200,000 to $300,000 and will take several months to be ready, the Coast Guard said. There is a possibility the driver could be held responsible.

"It's not unusual that the Coast Guard has asked people to reimburse the service for damages like that, but I'd be speculating as to the outcome," said Lt. John Titchen, Coast Guard spokesman.

The case was still under investigation, police spokeswoman Michelle Yu said yesterday.

The navigational tower helps boaters safely navigate through the channel that leads into Kewalo Basin. But boaters who use caution can still navigate safely through the channel, Titchen said.

The tower fell when it was hit by a Plymouth Voyager van driven by a 51-year-old man. The crumpled tower crashed onto the van and landed across all three Waikiki-bound lanes of Ala Moana boulevard, and onto an Oldsmobile traveling in the other direction.

The van's driver was seriously injured and his 13-year-old daughter, the only passenger, was in stable condition. No one was injured in the second car.

Mariners use two towers to line up their approach into the Kewalo Basin channel. The other tower, with the Kewalo Basin Entrance Front Range Light, is close to the water.

"(The range light) is critical, but it's not essential to navigation," Titchen said. "It's not like they can't transit without it. They just have to exercise caution."

Out at sea, boat helmsmen would line up their vessels with the two lights, putting their boats on course in the middle of the channel, Titchen said. Also at the entrance to the channel are lighted buoys — one red and one green — and mariners know to keep the red buoy to the right upon return, he said.

Capt. Ron Opy, with Kuu Huapala Fishing Co. at Kewalo Basin, said he arrived after dark on the day of the accident and had no problem entering safely. He credited recent changes the Coast Guard made to buoys in the channel, including lighting the two at the entrance and an additional buoy near where surfers enter the water off Point Panic.

Thirty years of experience and local knowledge also helps, Opy said, adding that even newcomers should be able to get in. "It's a common-sense thing, but not everybody has common sense," he said.

Bob McCowan, owner of Blue Nun Sport Fishing in Kewalo, said any long-term delay in replacing the tower could be a problem.

"We have all these new pleasure boats that aren't very experienced going in and out of that particular harbor," McCowan said. "I can't say for sure it's going to be, but I can see how it could possibly be a problem."