Twice when Roxane Moore was riding on a city bus, the driver had to respond to an altercation between passengers.

"There was almost a fistfight," she said about one situation.

Both times the driver had to stop the bus, but police were called only once.

Moore said she understands why Oahu Transit Services is installing security cameras on TheBus vehicles. The company announced this week it intends to eventually place cameras on all 525 of its buses.

"I guess if it got to the point of some type of civil suit, it could be used as evidence," she said as she waited at the Alapai Transit Center on Friday. "People lie. They’re good at lying."

A few buses have been making their rounds with the cameras since Wednesday, and 10 camera-equipped buses will take part in an official 30-day test period beginning Tuesday.

Ralph Nishimura, general supervisor of transportation for TheBus, said the cameras will help verify or refute claims or complaints against drivers and determine liability for traffic accidents that cause on-board injuries.

"They’re just tired of getting falsely accused," Nishimura said of the bus drivers.

Lloyd Cantere, a bus driver for seven years, agreed, pointing out that sometimes other passengers think they know how an incident between passengers or the bus driver and a passenger played out, but they might not have all the facts straight.

"There’s always that third party, and it’s not always right what they say," Cantere said.

He said he also thinks the cameras will be a deterrent to drivers tempted to bend the rules.

"It will keep the bus drivers in line, too, as far as cellphone using," he said. "They’ll be more alert behind the wheel."

Keith Garlock, a driver for 3 1/2 years, had a similar sentiment but noted that some people might feel uncomfortable being watched.

"Your first impression is maybe you’ll be against it," he said. "(But) I think it can be an added bonus for us and our service."

Three internal-view and three external-view cameras monitor passengers entering, riding and exiting the bus, as well as traffic signals and the movements of other vehicles on the road.

At least five signs in and around the bus notify riders and other drivers that their actions are being recorded. The footage will be stored for a month and only viewed following an incident such as an accident, Nishimura said.

Bus patron Doreen Kapuakela said she knew she was riding on a bus outfitted with the new cameras when she saw one of the signs.

Kapuakela commutes to work on TheBus daily, and she joked the only thing new about her ride was that now "you’ve just got to smile on the camera. … I don’t hear anyone complaining."

Mike Thomas, a visitor from Addison, Ill., said that the thought of being video-recorded on the bus does not trouble him.

"I’m for anything that tries to keep people more leery of doing something wrong," he said.

Two exterior cameras are mounted on either side of the front of the bus to view traffic; a forward-looking camera is mounted on the inside of the windshield; another sits on the wall just above the driver’s head to capture riders as they load the bus; and two are situated in the seating area, covering the entire passenger cabin.

The rear interior camera is important, Nishimura said, because TheBus officials will be able to review footage of people exiting the rear door, especially when customers claim injuries from falling down the step.

"We know that the cameras will help at least give us a good picture of what actually went on with the bus at the time (of an incident)," said Ralph Faufata, OTS vice president.

Faufata said customers can expect cameras to be installed on at least 200 buses in the 525-bus fleet by the end of 2012.

He estimated the cameras cost $4,000 to $5,000 per bus. The cost for the first three phases of the six-phase project, which includes a central control system and camera installation on 158 buses, is $1.03 million.

In the future, Faufata said, Oahu Transit Services will buy new buses with cameras already installed.