If gas prices aren't enough to threaten your wallet during holiday travel, consider a photo speed-enforcement ticket.

Motorists traveling any stretch of Interstate 10 or Interstate 40 across Arizona between 3 and 11 p.m. today will encounter speed-enforcement devices every 20 miles.

The move is part of a nationwide strategy to keep highways safe on a busy travel day, said Roger Vanderpool, director of the Arizona Department of Public Safety.

AAA officials estimate about 41 million Americans will travel 50 or more miles from home this Thanksgiving weekend. About 33.2 million are expected to drive to their destinations.

DPS is using its entire fleet of 42 speed-enforcement vans and about 20 fixed units to cover all of I-10 and I-40 in Arizona.

Units are triggered when a driver is going 10 mph or more past the posted speed limit.

Violators are notified by mail within 30 days and must pay a fine of roughly $185.

The civil violation does not have any bearing on a driver's license, but anyone caught traveling at 20 mph or more over the speed limit will face a criminal charge.

DPS operates more than 60 mobile-speed cameras.