In Georgia, city police and county sheriff's deputies using radar must allow a 10 mph cushion except in school zones and historic districts where pedestrians are likely. State troopers use their own discretion.
"Additionally on enforcement, troopers will generally target the higher speeds first since crash severity is compounded as the speeds go higher," said Gordy Wright, spokesman for the Department of Public Safety.
It may not be surprising, then, that motorists pick different speeds as their idea of what is proper. For some, it's the speed limit. For others, just shy of 10 mph over, and still others aim to be slower than the fastest vehicle.
Naturally, that leads to some frustration when they encounter each other.
That may explain the public support for a bill in 2010 that would have required motorists in the left-hand lane to yield to a faster driver coming from behind wanting to pass. However, only vehicles driving below the speed limit would have been forced to move over.
The bill failed to pass and wasn't re-introduced this year. The current law doesn't require speeders to get out of each other's way, and as long as there's an undefined practical speed limit, drivers on Georgia roads are on their own when it comes to guessing the actual allowable maximum.
Georgia's troopers split their time between rural highways and the interstates, targeting the fastest motorists. That's because Georgia has only 24 more troopers than it did 30 years ago when the population was roughly half.
"We have a serious shortage of troopers on the road," said Rep. Tim Bearden, R-Villa Ricca, chairman of the House Public Safety & Homeland Security Committee.
The safest roads are the interstates, according to federal statistics, but the Georgia State Patrol won't focus exclusively on where the greatest danger is. Instead, it will divide its resources, despite a manpower shortage.
However, they do concentrate on the fastest drivers, according to Wright.
So, does leaving speeders immune to tickets as long as they're not the fastest cars on the road make bad policy?
"No, intercepting the high-end speeders reduces the potential for that driver to be involved in a serious crash," he said.
Monday, Georgia is joining with other Southern states in a media campaign called 100 Days of Summer HEAT, or Highway Enforcement of Aggressive Traffic. Troopers and local law-enforcement officers will be visible in their enforcement of speed limits and the law requiring seat belts.
Seat-belt compliance and speed-related fatalities have been improving nationally and in Georgia. Since 2005, yearly speed-related deaths have dropped from 340 to 238 in 2009, according to the National Highway Traffic Safety Administration. Seat-belt usage has hovered at 90 percent in that period, but it was as low as 58 percent in 1994.
Still, the Peach State is a dangerous place to drive, no matter how it's measured.
In terms of total fatalities - regardless of cause - 1,284 died in 2009. Viewed per 100 million miles driven, the rate of death on Georgia roads in 2009 was 1.18 compared with the national average of 1.14. In terms of fatalities per 100,000 population, the state's rate of 13.06 was still above the national average of 11.01.
Getting the rate down to the national average in terms of population would save 201 lives yearly. Matching the U.S. average mileage rate would save 44 lives.
Georgia is better than the national average in one respect. Speed was a factor in 31 percent of all fatal wrecks across the country, but it factored into just 19 percent of Georgia's killer accidents.
One other figure jumps out: the difference between rural roads and urban streets. Drivers are nearly twice as likely to die on a road in the middle of nowhere.
Of course, Georgia has a lot of rural roads to patrol. With a limited number of troopers, below the nation's per-capita average even before the recession, state officials have a challenge covering all the bases.
Technology is what experts call a force multiplier. Some states use unmanned patrol cars parked near roads as decoys. Others use unmanned radar devices that either flash a driver's speed on a billboard or take a picture of the vehicle's tag to automatically cite the owner by mail.
Such technology isn't popular with everyone. AAA Auto Club South, for instance, accepts that it might be necessary in places but prefers humans handing out the tickets.
"We would hope that all patrol cars are identifiable," said Karen Morgan, AAA spokeswoman.
From a legislative standpoint, Bearden agrees because automatic radar cameras aren't calibrated as often as those operated by officers.
"I think an officer is the one that should be writing tickets," said Bearden, a former policeman.
Instead of hidden detection devices, visibility is the key to slowing drivers, he said. In Douglasville, highway traffic slowed when approaching that city because its 10 motorcycle patrolmen were so visible, he said.
National experts feel the same way, according to Barbara Hersha, executive director of the national Governor's Highway Safety Association.
"The idea behind general deterrence is law enforcement can't be everywhere. So, you want them to be on the road in a very visible way," she said. "The purpose is not necessarily to write tickets or raise revenue but to do it in such a way that drivers are safer."
And she would deploy that show of manpower along the roads shown by statistics to be the most deadly. That's at odds with the Georgia State Patrol.
"If the crash statistics indicate, yes, it makes sense for law enforcement to put a vehicle there to enforce the speed limit," she said.
Contact Walter C. Jones: (404) 589-8424