Several people avoided serious injury early yesterday when two trees fell on the Pali Highway, striking four vehicles.

The incidents came just two weeks after a tree fell on the highway and damaged several cars, snarled traffic and sent two people to a hospital.

Scott Ishikawa, spokesman for the state Department of Transportation, said high winds coupled with the fact that some of the trees haven't been trimmed in years and are very tall may be causing them to topple.

The state still plans a tree-trimming project along the Pali Highway this spring, Ishikawa said. But the Pali project will have to wait until a similar project now under way to remove or trim about 200 trees along the Likelike Highway concludes.

About half a dozen trees fell along that route last year, and some caused traffic delays, Ishikawa said.

Both of yesterday's incidents occurred between 12:30 and 1:30 a.m. The first tree came down near the tunnels and struck two vehicles, police said.

A second, larger tree fell a short time later about a half-mile from Waokanaka Road.

That tree, which was at least 3 to 4 feet in diameter at its base, also struck two vehicles, including a quad-cab Chevrolet pickup carrying four men who were traveling home to Waimanalo. The men in the pickup were treated at the scene and released.

The trees were cleared shortly before 6 a.m.

"One of the passengers in the pickup was a little shaken up; he said the tree just missed him," police Lt. Stan Lum said. "They all saw it falling about 25 feet in front of them and couldn't stop. It landed right on them."

On Dec. 28, a 30-foot tree slammed into the Honolulu-bound lanes of the highway just before rush hour. Two people were hurt in that accident.

The Transportation Department said it will meet with several private arborists and consult with The Outdoor Circle before the Pali work begins. Workers will cut back trees that overhang the highway or are deemed too heavy or termite-damaged.

They also will use a method called directional pruning, in which trees are trained to grow away from the roadway.

On the Likelike Highway, most of the problem trees are albizzias, the same species that the DOT removed along the H-2 Freeway last summer.

Most people who took the Pali Highway home yesterday were unaware of the early morning incidents, but some said the recent high winds have made falling trees more of a concern.

Kailua resident Don Dymond, 62, said he worries about falling trees, especially after heavy rains that soften the ground and make the trees unstable.

"You can't predict whether a tree's going to fall just by looking at it," he said. "If you did, you'd be a wizard."

"(The trees) add to the beauty of the drive, but the fact that they're falling on vehicles is, well, a touchy subject," said Rand Rehkemper, 44, a Kailua resident who either takes the H-3 or the Pali Highway home each day.

Rehkemper recalled past efforts to trim the Pali Highway's trees, which he said "didn't look great."

But "it's the price we pay for having that beauty alongside the road," he added.

Reach Dave Dondoneau at ddondoneau@honoluluadvertiser.com.