SPEED LIMITS: THEY'RE SET AFTER TRAFFIC SURVEYS

SIKESTON -- Contrary to what many people may think, speed limits on Missouri highways are not set in a random manner designed to snare unsuspecting drivers into speed traps or hinder traffic flows.

In fact, while they may not be aware of it, motorists actually play an important role in determining speed limits on Missouri highways, said Freeman McCullah, District 10 engineer for the Missouri Highway and Transportation Department in Sikeston.

"Speed limits don't just magically appear out of thin air, said McCullah. "A lot of work and study goes into determining speed limits," he said. "We don't put a bunch of numbers on a piece of paper, tack it to the wall, and throw darts at the numbers.

"Most drivers assume we set the speed limits, when, in fact, it is the drivers who use the highways that tell us what they feel is a safe and prudent speed limit."

By law, the Missouri Highway and Transportation Department has the final say on setting speed limits on state routes inside and out of municipalities. As a practical matter, however, the state tries to work closely with municipalities to come up with speed limits that are safe but realistic.

"If a municipality is not satisfied with the current speed limit on a state route, feels it's too high or too low, they can contact the highway department," McCullah said. "We will conduct a traffic survey, using a radar gun, to determine the actual speed at which 85 percent of the passing cars surveyed are traveling during a specified time period."

McCullah said the 85 percentile figure comes from a series of national studies that has shown that at any given time 85 percent of the drivers will drive at a speed they consider reasonable, safe and prudent for themselves and other motorists.

"In other words, we let the motorists tell us what they think the safe and prudent speed limit should be, and we make a recommendation to the municipality after it has been given conceptual approval by the highway commission in Jefferson City," McCullah said. "Of course, there are circumstances where a lower speed limit is recommended. If there are schools, nursing homes, lots of pedestrian traffic, hazardous intersections, or a concentration of commercial businesses along the highway, we take these into consideration and recommend a lower speed limit. In addition, we may also place warning signs to alert motorists of the hazard."

McCullah said surveys show if speed limits are artificially lowered for no legitimate reason - other than to create a speed trap for revenue purposes - the majority of drivers will ignore the speed limit, and it must be enforced with constant law enforcement pressure.

On the other hand, most drivers will reduce their speed if they realize there are hazards ahead. "If you don't believe it, just drive along a stretch of busy highway, such as North Kingshighway in Cape, where traffic conditions vary according to location," McCullah said. "Where there is a high density of traffic, most people drive slower because they perceive there is a hazard from other traffic. When they reach the north or south end of the city, where traffic is less dense, the average speed picks up. That's why there is no single, fixed speed limit on Kingshighway or any other urban route."

McCullah said attempts are sometimes made to lower a speed limit as a result of a single fatality or one or two accidents that may have occurred along a particular stretch of highway. "This usually does not succeed because, in most cases, the accident or fatality was the result of human error or mechanical failure, and not a design defect of the highway," he explained. "Anytime you try to lower the speed limit for no good reason, the majority of drivers will ignore the lower speed limit."

Jack Grimes, who conducts radar speed surveys in District 10, said a good example of this occurred in a small community in the district. "They wanted us to lower the speed limit from 25 to 15 mph. We used the radar gun and found the average speed was 32 mph. But they wanted the speed limit lowered, so we let them. The police started issuing speeding tickets to everybody in town; it was a small town, and it wasn't long before the telephone at city hall started ringing off the hook. The police judge wound up throwing out all of the speeding tickets, and the city finally went back to the original speed limit," Grimes said.

"On the other hand, we can lower the speed limit 10 percent if the accident rate in a particular area is twice the state average or if there is a high density of driveways or entrances onto the highway in the area that would create a traffic hazard."

When a radar speed survey is conducted in a community, Grimes tries to be as invisible as possible. "We never do surveys on a Monday or Friday; they are done on weekdays - usually mid-week, when the weather is good, and the traffic flow is as near normal as possible. We want to observe free-flowing traffic without being observed. If drivers become aware of the radar gun, we will move to another location or come back later in the day."

Grimes said a recent radar speed survey was conducted for the city of Jackson on the new five-lane stretch of East Jackson Boulevard, from the Highway 25-72-34-61 intersection eastward to the Cape Girardeau city limits at I-55. The speed limit had not been changed since the highway was enlarged from two to five-lanes.

As a result of the radar speed survey, the Jackson Board of Aldermen voted in December to raise the speed limit on East Jackson to 55 mph, from the city limits west to Williams Creek. From Williams Creek to Gloria Street, the limit was raised to 50 mph. From Gloria to Shawnee, it was raised from 35 to 40 mph. It remains 35 mph from Shawnee to the Highway 25-72-34-61 intersection.

"The bottom line is that we make every attempt to recommend and set speed limits that are considered safe in the minds of 85 percent of the drivers that are surveyed. They are telling us something, and we listen to them," said Grimes.