The number of fatal accidents decreased by one, from nine to eight, with the cameras, the data show.
An increase in crashes may be due to drivers stopping abruptly to avoid running a red light and being struck from behind, police said.
"Are they driving too quickly and slamming on the brakes?" said police spokesman Lt. Raymond Evers. "That's probably not the complete answer. There are a lot of variables. ... Was there an increase in traffic volume, was there construction? We're not sure why it's happening."
Police Commissioner Charles H. Ramsey continues to advocate for the cameras. "He said he wishes speed cameras could be installed, too," Evers said.
The chief of the Parking Authority and some highway safety experts questioned the validity of the police data.
"We believe the cameras are having a positive effect," said Parking Authority Executive Director Vincent J. Fenerty. "Overall, crashes are down, and [red-light] citations are down about 90 percent. Drivers' habits have changed, and traffic has slowed down."
The Parking Authority's own analysis last month of recent crashes at three red-light-camera intersections on Roosevelt Boulevard found accidents down by 8.5 percent with injury accidents up by 8 percent.
The crash data showing an increase in accidents was provided by the police Research and Planning Unit in response to a request by The Inquirer.
Accident tallies varied from intersection to intersection, with some showing significant drops in accidents, such as at Roosevelt Boulevard and Cottman Avenue, where there were 179 accidents in the two years before cameras and 99 in the two years after cameras were installed in 2005.
Other intersections showed large increases in accidents, such as at Roosevelt Boulevard and Southampton Road, where there were 182 accidents in the three years before cameras and 255 in the three years after cameras were installed in 2007.
Philadelphia is the only city in Pennsylvania allowed to operate red-light cameras, although the legislature is considering expanding the program to other cities.
The current authorization for the Automated Red Light Enforcement program will expire at the end of this year, unless the legislature votes to extend the authorization, as it has four times in the past.
Red-light cameras have generated controversy around the nation, with many safety advocates arguing that cameras reduce crashes and save lives, while opponents contend the primary benefit is more revenue for states and cities.
"It's common for cameras to produce more accidents," said Jim Walker, with a Wisconsin-based anti-camera group, the National Motorists Association. "Some people slam on their brakes and get hit from behind."
He said increasing the time of yellow lights would improve safety more than red-light cameras.
Crashes caused by red-light running killed 762 people in 2008, according to the National Highway Traffic Safety Administration. About 165,000 people are injured annually by red-light runners, the NHTSA estimates.
Different cities have reported varying results with red-light cameras, with most showing decreases in fatal crashes. Several cities, including Houston and Los Angeles, this year abandoned their red-light camera programs.
The Insurance Institute for Highway Safety estimates that red-light cameras saved 159 lives in 14 U.S. cities between 2004 and 2008.
The Pennsylvania Department of Transportation reviewed "reportable" accidents (those involving death, injury, or damage requiring a tow) at 10 intersections in Philadelphia and found those accidents dropped 21 percent, from 157 a year before cameras to 124 a year after cameras. Reportable accidents were down at eight intersections and up at two, PennDot found.
An analysis last month by a Parking Authority consultant of all accidents at three intersections on Roosevelt Boulevard found crashes down at Red Lion Road and Cottman Avenue and up at Grant Avenue.
The consultant, Thomas J. Nestel, chief of the Upper Moreland Police Department, said his data were more detailed than the Philadelphia police data and better reflected the true accident history.
Nestel's research showed total crashes down 8.5 percent at the three intersections and injury crashes up 8 percent.
Jim Lardear, a spokesman for AAA Mid-Atlantic, said the increase in accidents shown by the police data was "disappointing."
"The only reason to deploy red-light cameras is to promote traffic safety," Lardear said. "AAA believes that, when applied appropriately, cameras can deter red-light running and prevent the most serious crashes."
He cited a 2005 federal study that concluded red-light cameras produced a modest benefit in seven cities, with 375 more rear-end collisions and 379 fewer side-impact collisions.
Lardear asked: "Could better engineering, lighting, or a few gallons of paint reduce crashes far less expensively?"
The Parking Authority now has 90 cameras at 20 intersections; the most recent were added this month at Broad and Vine Streets.
Motorists are fined $100 if they are caught by the cameras running a red light, and since 2005, the program has been a lucrative source of income: Motorists have paid $45.3 million in fines since 2005, of which $21.1 million has gone to PennDot.
The rest of the money - $24.2 million - has gone to pay the expenses for operating the program, mainly to American Traffic Solutions Inc., the Scottsdale, Ariz., company that installs and maintains the cameras, and to the Parking Authority.
PennDot distributes its revenue from the camera program for transportation projects: half to Philadelphia and half to the rest of the state.
So far, Philadelphia has received $8.4 million; another $8.4 million has gone to 116 other municipalities in the state. Philadelphia is to get $1.5 million more, and a like amount will go to the rest of the state.
State Rep. Mike McGeehan (D., Phila.), the ranking Democrat on the state House Transportation Committee, said he plans to offer legislation soon to extend the camera program and to require the fine money remain in the city where the cameras are.
But Transportation Committee Chairman Rep. Richard Geist (R., Blair) says the revenues should be divided.
Geist said he favors expanding the program to other Pennsylvania cities, "if it's done prudently - only for safety and not for revenue."
Red-light violations have dropped dramatically at most Philadelphia camera intersections, as motorists become aware of the cameras and the prospect of a $100 fine.
At Roosevelt Boulevard and Grant Avenue, where cameras have been in place since 2005, the number of violations dropped from 4,000 a month in the first year to about 300 a month this year.
The next intersection to be equipped with cameras will be Island Avenue and Lindburgh Boulevard in South Philadelphia, expected to be operational next month.
Four other intersections are awaiting approval by City Council and PennDot for installation of red-light cameras: Academy Road and Grant Avenue; Knights Road and Woodhaven Road; Byberry Road and Worthington Road; and Byberry Road and Bustleton Avenue.
Contact staff writer Paul Nussbaum at 215-854-4587 or email@example.com.