West O'ahu motorists heading to town on Monday morning, take note: You'll be sharing rush-hour roadways with many of the 50,000 students headed to the first day of classes at the University of Hawai'i and various private schools.

"That's when you see an increased number of freeway users," said Rodney Haraga, the director of the state's Department of Transportation, noting that the morning traffic could teeter at gridlock.

The freeway traffic will be heavier than two weeks ago when public schools opened because those students typically travel in their residential communities and don't use the state highways, Haraga said.

In an effort to ease the annual traffic jam, state and city officials yesterday unveiled a traffic campaign dubbed: "Beat the School Jam."

"We're advising commuters to leave early or later to avoid morning rush hour and make sure that their vehicles are maintained — we don't want them breaking (down) on the freeways," Haraga said.

Officials are also encouraging alternative modes of transportation, such as car pooling, van pooling, riding the bus, bicycling and walking.

Vicki Harris, executive director of Vanpool Hawai'i, said a van-pool seat, which costs $55 monthly, is an affordable alternative to driving alone. Additionally, van-pool drivers get to use the vehicles — seven-seat or 15-seat vans — after their daily commute and on weekends with insurance covered, she said.

Noting that vehicles are available, Harris quipped, "We can get you in before that day of doom comes and becomes a reality."

To further ease the congestion, the state will suspend nearly all state highway construction projects on O'ahu until Sept. 5, Haraga said. Night work will continue as scheduled.

The city will also restrict road construction, said Melvin Kaku, director of transportation services. There will be no road closures for construction activities near schools from 9 a.m. to 2 p.m., from Monday until Sept. 1. Also, there will be no major roadwork on city roads from 9 a.m. to 3 p.m. from Monday to Sept 1.

Haraga said there are about 650,000 registered vehicles on O'ahu. There are about 900,000 residents, according to census figures. "It will be a problem when we get to that one-to-one ratio here on O'ahu," he said, adding that O'ahu is the only island where the population outnumbers registered vehicles.

Haraga also announced yesterday that two signs displaying the speed of on-coming cars will be installed in Waimanalo. The signs will record data such as how many cars pass and how fast they are driving, but they will not record license plates of passing cars, Haraga said. They will be installed near Waimanalo Elementary and Intermediate School.

Reach Robert Shikina at rshikina@honoluluadvertiser.com.