How fast is too fast?
Kentucky considering a 70 MPH speed limit
By Dan Hassert
Post staff reporter
A University of Kentucky study of driver habits in 1997 came to this interesting conclusion - no matter what number is on the black-and-white speed limit signs, drivers will travel at the speed they want to.
Even when the speed limit changes.
As evidence, the study cited numerous measures of 85th percentile speed (a commonly used engineering tool that measures the speed at which 85 percent of vehicles are traveling at, or below).
For example: Back when the speed limit on Ky. 9 in Campbell County was 55 mph, the 85th percentile speed was 58.2 mph. When the limit was dropped to 45 mph, the 85th percentile speed changed only slightly, to 57.3.
Similarly, when the speed limit on Ky. 536 in Boone County was increased from 35 mph to 45 mph, the 85th percentile speed changed only from 44.8 mph to 46.2 mph.
In fact, the study, by the Kentucky Transportation Center at UK, looked at 122 locations where speed limits were changed, from decreases of 20 mph to increases of 10 mph. In no category of change was the resulting change in 85th percentile speeds statistically significant.
"People tend to drive at what they think is a reasonable speed,'' said Jerry Pigman, manager of the center's traffic and safety section. "The sign put out there on the highway doesn't control it nearly as much as the perceived condition of the road - hills, curves, volume of traffic out there.''
The UK study recommended that the speed limit on interstate highways in rural areas be increased from 65 mph to 70 mph in Kentucky, since tests showed the 85th percentile speed to be 72.9 mph, Pigman said.
That fact is being cited by those involved in a new push for a 70 mph limit.
Gov. Ernie Fletcher endorsed such an increase during his State of the Commonwealth speech Jan. 9. And a bill pending before the General Assembly would mandate the change.
Proponents say the interstates and modern cars are designed for such speeds and that it would be safer because the disparity of speeds would be lessened on the highways.
But opponents scoff, saying the proposal ignores both the tendencies of human nature and the laws of physics - with permission drivers will simply driver faster, and at higher speeds drivers get into trouble faster, have less time to react and get out of trouble, vehicles take longer to stop and wrecks happen with more force.
"If killing more people is a bad idea, then (the increase) is a bad idea,'' said Richard Retting, senior transportation engineer for the Insurance Institute for Highway Safety, who cited studies that show more accidents, injuries and deaths at higher speeds. Drivers simply drive faster with higher limits, he said.
Just how fast drivers should be allowed to go has been a controversial debate around the nation since 1974, when Congress - in response to a national energy shortage - set a National Maximum Speed Limit (NMSL) of 55 mph.
Despite the immediate reduction in highway deaths, the 55 mph limit was unpopular, and in 1987, Congress let states move to 65 mph on rural interstates. In 1995, Congress repealed the NMSL altogether and gave full authority to set limits to the states.
Many states immediately increased their limits. Today, speed limits on interstates range from 55 mph in the District of Columbia to 75 mph in 12 states, all out west. The limit in Tennessee, West Virginia, Indiana and Missouri is 70. In Illinois and Ohio, it remains 65 mph for cars and 55 mph for trucks.
Sgt. Tony Bradshaw of the Ohio Highway Patrol says there is little discussion in Ohio of raising the speed limit, particularly because fatalities jumped 6 percent after the increase to 65 mph in 1987 and because the number of accidents increased 24 percent after the speed limit for trucks was raised to 65 mph on the Ohio Turnpike in 2004.
But Sgt. Travis Tennill of the Kentucky State Police said law enforcement officials in the Bluegrass state support a small increase in the speed limit, particularly if it's combined with a bill that lets police pull drivers over for not wearing their seat belts. "Based on everything we've seen, it should have a limited effect, if any at all, (on safety),'' Tennill said of a 70 mph limit.
Tennill said he couldn't say whether troopers would more stringently enforce a 70 mph limit than 65 mph, but he said they were very concerned about seat belts. Low seat belt use, lots of hilly roads and factors like alcohol use make Kentucky's road fatality rates some of the highest in the nation.
Kentucky had 968 highway fatalities in 2005, up slightly from 2004 and up from 823 in 2000. Fatality rates per 100 million vehicle miles have gone up similarly recently, a fact that puzzles many experts.
But interstates are much safer than two-lane country roads because of the terrain and because seat belt use is higher (79 percent on interstates compared to 51.4 percent on rural roads), Tennill said. Only 9 percent of collisions on interstates are fatal, he said.
The 1997 UK study showed little difference in accident rates, fatality rates or injury rates between interstates with 55 mph or 65 mph limits.
But Retting said national statistics show just the opposite. A study published in 1999 by the Insurance Institute said the 24 states that raised speed limits in 1995-96 showed an increase in deaths of 15 percent, or 17 percent when the miles driven were factored in, he said. In states that didn't raise limits, there was no increase, he said. "At higher speed, no good can come of it, danger-wise,'' he said.
What people fail to realize is the force of impact in a wreck goes up exponentially when speed increases - if speed is 5 mph higher, the impact is 25 times (5 squared) greater, he said. While better design features like air bags enable modern vehicles to absorb more energy at less danger to occupants, at higher speeds they have more energy to absorb - a 50 percent increase in speed, from 40 mph to 60 mph, for example, produces 125 percent more energy, he said.
And while the difference in numbers of drivers traveling faster might be "negligible'' with different speed limits, "negligible'' can mean a few lives, he said.
Reaction to the 70 mph proposal has varied.
Florence resident Bill Kraatz said highway safety has more to do with drivers being alert than the speed limit. "I think it's a wonderful idea," Kraatz said of 70 mph.
Since Kraatz said he already drove at 75 to 80 and was comfortable with those speeds, he didn't think a higher limit would cause him to drive faster.
But Pam Creutz, who drives from Alexandria to Blue Ash, Ohio, every day to get to work, said she already sees too many people driving too fast, cutting others off and tailgating. "I've seen so many horrendous accidents ... if they bump it up another 5 mph it's going to be a disaster,'' she said.
But former truck driver Todd Spencer said he thought accidents would decrease because people wouldn't be so frustrated by the lower limits.
"If you post speed limit signs lower than people perceive as reasonable and prudent, they ignore them and then you have more accidents,'' said Spencer, the executive vice president of the Owner-Occupied Independent Drivers Association in Missouri.
The association represents 133,690 truckers nationwide, including 2,732 in Kentucky and 7,438 in Ohio. While the higher speed limits would help truckers save time and money in some instances, it's the safety aspect that is most important, he said. Drivers afraid to go with the flow of traffic at 70-75 mph for fear of getting a ticket would lose that fear and drive the same as everybody else, he said.
A spokesman for the Wisconsin-based National Motorists Association echoed that statement. Drivers now must make a difficult decision, said communications director Eric Skrum: "I can do the safe thing by going with the flow and risk a ticket, or I can do the unsafe thing and observe the speed limit,'' he said. "It's not the speed itself that kills, it's the speed disparity that kills.''
And people who think that that speed disparity will be widened by elderly drivers who aren't comfortable with higher speeds need not worry, said Don Pendleton, Kentucky coordinator for driver safety for the AARP.
"It's more of a problem when states are different,'' he said. Drivers are already used to driving 70 mph or greater in states like Florida, North Carolina and Michigan. AARP advises elderly drivers who aren't comfortable driving at those speeds to stay off the highways in the first place.
One reason Gov. Fletcher proposed the higher limit has to do with surrounding states, spokesman Brett Hall said.
"Sixty-five is OK, but we have states in this region - West Virginia, Tennessee, Georgia - that have a 70 mph speed limit. There's no reason we can't transition (to that),'' Hall said.
Fletcher also believes matching the limit to current speeds would create more efficient enforcement, Hall said.
At one time Fletcher mentioned packaging the 70 mph proposal with a primary seat belt law, but he's not proposing that right now, Hall said.
Such a link would definitely kill all chances for the higher speed limit, since opposition to the seat belt proposal is so fierce, said two members of the House Transportation committee, Republican Paul Marcotte of Union and Democrat Hubert Collins of Whitinsville.
While Marcotte said a stand-alone speed increase might stand a chance, committee Chairman Collins disagreed. He said he has no intention of bringing the speed limit bill sponsored by Mike Weaver, D-Elizabethtown, up for discussion. But, if the Senate passes legislation and sends it over to the House, he'd consider a higher limit in limited areas of the state.
Two previous bills - a push for 75 mph in 2005 and a push for 70 mph in 2003 - died in the Transportation committee.