PHOENIX — State police awarded a contract for photo enforcement of traffic laws that pays the successful bidder based on the number of people who pay their tickets.

The deal, made public Thursday, gives Redflex Traffic Systems $28.75 out of every $165 paid to the state for speeding. The state actually could get a bigger chunk: One provision of the contract for 100 fixed and mobile cameras provides a volume discount, with Redflex taking only $16.95 per citation.

More tickets issued by Redflex also means more money for the state: A special law approved by lawmakers at the behest of Gov. Janet Napolitano put all the net revenues into the general fund. Proceeds from all other traffic citations normally go to the city or county where the ticket is issued.

Napolitano, in some early projections, figured Arizona would net $90 million by next June 30.

This arrangement is a departure from the pilot project started last year where the state Department of Public Safety simply leased two vans — and the drivers to go with them — for a flat $3,940 a month. DPS Commander Thomas Woodward said that was done on purpose.

“The revenue stream from the citations will rise and fall with the cost of administrating the program,” he said.

Plans are to have the first 50 cameras operating on Sept. 26. That is the day the new law on statewide photo enforcement — including the provision giving all the cash to the state — takes effect.

That same law also provides $4 million to the administrative office of the Arizona Supreme Court to deal with costs. Whether that cash will be shared with the city and justice courts that handle contested citations, though, remains unclear.

The other 50 cameras should be in place by the end of the year.

Not all of these will use radar to determine speed. Woodward said some of the fixed cameras will instead rely on sensors built into the pavement.

Woodward said his agency has no idea how many citations will be issued during the year.

The new law assumes that the state will pay $20 million to Redflex between late September and the end of the fiscal year next June 30.

Napolitano’s $90 million projection is based on most people paying the tickets.

The governor admitted the legislation was crafted to encourage people to pay the fine and not contest the tickets.

Normal speeding citations carry three points. Eight points in a year send a motorist to traffic survival school; 12 points suspends a license.

Violators captured by the state’s photo enforcement will get no points. And the law also prohibits the state from reporting photo violations to insurance companies seeking to boost premiums.

The actual fine for errant motorists will be $181.50. That includes a 10 percent surcharge that helps to fund Arizona’s voluntary system of public financing of candidates for statewide and legislative office.

Woodward said most of the fixed cameras will be installed initially along sections of freeway in Maricopa County where collision rates are high. Fixed cameras also are planned eventually for areas in Pima County.

There also are plans for some fixed cameras along state roads to catch motorists who run red lights. Woodward said likely priorities include Apache Junction, Sierra Vista and Bullhead City.

But Woodward also said each of the state’s DPS districts will get two or three mobile cameras, with the commanders of each area deciding where to place them on any given day.

“That’s determined based on collision statistics, collision pictures, problem areas where we see a high incidence of speeders,” Woodward said. He also said DPS will respond to public requests to locate mobile vans in specific areas.

The idea of a price linked to the number of paid citations is not unusual. Jay Heiler, a Redflex spokesman, said many of the contracts they have with other communities, including several in Arizona, have similar provisions.

Heiler also said basing the fee on paid citations — versus tickets written — is fair for his company, the state and motorists because there’s no incentive to issue notices of violation in cases where the driver’s guilt is less than clear.

But Heiler said citations will be mailed out even in cases where it is possible they will be ignored.

While lawmakers revamped the photo enforcement laws, they left intact existing provisions which allow the state to go after only the person behind the wheel.

That means if the registered owner — who gets the notice in the mail — is not the driver, the ticket will be dismissed. But Woodward said the owner will get an “opportunity to tell us who is driving.”

“A very large number of people do tell us who the driver is,” he added.

Similarly, if the vehicle is registered in the name of the business, that firm is not required to pay or provide the identity of the driver. But Heiler said Redflex still will mail the citation because the business owner might want to know that an employee was seen speeding.

“They might tell us to pound sand,” he said. But Heiler said the company might also decide to make the employee pay the fine. The U.S. branch of Redflex, based in Scottsdale, actually is a subsidiary of Redflex Holdings Group, incorporated in Australia.