Police plan on increasing enforcement on O'ahu roads and at Ala Moana Beach Park in anticipation of a busy weekend that will, in effect, stretch through Tuesday because of the Fourth of July holiday.

The Honolulu Police Department yesterday said it will set up more sobriety checkpoints to try to cut down on drunken driving. It will also post as many as 130 officers at the beach park Tuesday to discourage illegal fireworks and prevent injuries during the Fourth of July celebration there.

"We want to try to get it under control a little sooner compared to what was happening in the past," police Sgt. William Axt said. "We want to make it safe and enjoyable for families to come."

Fireworks in the park are a large concern because many people don't know fireworks are illegal in the park, Axt said.

Meanwhile, police began operating sobriety checkpoints last night at unannounced times and locations. The extended checkpoints will continue through Tuesday night.

Through Wednesday, there have been 51 traffic fatalities on O'ahu compared with 40 at the same point last year.

Police are also asking the public to make the Ala Moana Beach Park celebration on Tuesday a safe experience by not consuming alcohol or using fireworks in the park, where 50,000 people are expected to turn out to watch the fireworks.

Officers patrolling the park that day will watch for traffic violations, alcohol consumption, illegal parking and other park violations, police said.

Sparklers, fountains, aerial fireworks and firecrackers are illegal in all public parks. Undercover officers will patrol Ala Moana Beach Park to deter the use of such items.

"When there's so many people in the park, even one person setting off an aerial ... creates a hazardous situation for people that are there just picnicking," Axt said.

Those convicted of popping fireworks in a public park could be fined up to $2,000. People convicted of consuming alcohol in a public park could be fined up to $1,000.

Reach Robert Shikina at rshikina@honoluluadvertiser.com.