A Speeding Vaccine

A SPEEDING VACCINE

By Carl Fors, Speed Measurement Laboratories, Inc.

In speaking before city councils, I am constantly amazed when governmental entities naively believe lowering the speed limit will lower speeds. Many of them still think the Earth is flat.

Research Results

Martin J. Parker’s USDOT study (FHWA-RD-92-084) covered 22 states at 100 sites over several years, examining the effects of lowering and raising the speed limit in the city setting. He found (along with other researchers) that lowering the speed limit had no effect on the speed at which drivers drive. This is not just a snapshot because it involved over a million vehicles. Astoundingly, Parker found accidents actually increased by 5.4% when speed limits were lowered below the 85th percentile. Speed Measurement Laboratories, Inc. (SML) studied the same issue over five years on rural interstates in five western states, involving some 80,000 vehicles and found identical results: Regardless of the speed limit, drivers drive at the speed they feel is “reasonable and prudent.”

City councils and managers frequently call on local law enforcement to enforce the unrealistic speed limits they have set and expect the police department to be the expert in controlling speeds. When the patrol car is present, traffic slows. As soon as it leaves, traffic resumes speeding. Usually, in larger departments, there is a traffic division. In smaller departments, the traffic division is a one or two person team. The chief tells the traffic division to give him/her research on equipment designed to control speeds and the fact-finding fingers frantically search the Internet. There is little to be found there.

The Researched Cure

This article endeavors to provide rock solid research on what works and what doesn’t. It’s up to you to have the courage to present the facts to the decision-makers. You can continue to do it the old way – with a picture of an officer on the front page of the local paper holding a new radar gun touting the department’s answer to the speeding problem. Unfortunately, radar and radar tickets have little effect on reducing speeding! Issuing tickets does provide the personal gratification of getting something accomplished, but it has no effect on long-term speed reduction.

SML surveyed 3,800 drivers on speed awareness. The study was conducted in six communities in three states. The results showed that eighty-five percent of the sample had no idea how fast they were going.

Radar displays have proven their effectiveness in controlling speeds. Once made aware of their speed by these displays, drivers do come into compliance. The Texas Transportation Institute at Texas A&M University, with the assistance of SML, has published two research studies, i.e., Evaluation of Dynamic Speed Display Signs (September 2003, report #0-4475-1) and Evaluation of Speed Trailers at High-Speed Temporary Work Zones (January 2000, report #00-1475). The reports found that “the average speed dropped substantially from 44.5 mph to 35.3 mph shortly after the sign was installed. Installing the signs resulted in a significant decrease in average speeds which was maintained over a 16 week period.” So much for the objection from the back of the city council room by the self-appointed local traffic expert, “They may work for the first day, but, after people get accustomed to them, they will not work.” He, like the city council and the police chief, should look at the research. Applied to interstate work zones, the study reported, “Speed displays used at rural high-speed temporary work zones can be expected to produce speed reductions of about five miles per hour inside the work zone.” SML also assisted the University of Nebraska when it studied the short- and long-term effectiveness of radar displays (see Radar Speed Reporting Systems, March 2000). The sample size exceeded 45,000 vehicles. This study concluded that “the system was found to be effective in lowering speeds and increasing uniformity of speeds. Its effects increased speed limit compliance to 90% or more.” The city of Phoenix conducted their own research into the effectiveness of LED and non-LED radar displays in school zones. The study found LED displays with “violator alert strobes” to be vastly superior, showing “a speed reduction of seven miles per hour and that vehicles were down to the 15 mph speed limit entering the school zone.” SML’s published research #SML0900-27 of speed reduction in El Paso, TX, school zones showed similar results using a Stalker SpeedBoard with a “violation alert strobe.” Before placement of the radar display, only five percent of drivers were obeying the school zone speed limit of 15 mph. After placement, 72% of the drivers were at (or below) the speed limit. Three weeks after the radar display placement, the speed limit compliance percentage held and increased to 73% of drivers at (or below) the speed limit.

Additional Findings

SML has worked with the Mid-West Smart Workzone Deployment Initiative (MWSWZDI) since its inception in 1998. This consortium of Nebraska, Kansas, Iowa, and Missouri DOTs banded together to find out what does and doesn’t work. They came to SML with a request for a radar display specifically designed for interstate DOT use. They offered many ideas, including adding a strobe which flashes at the driver when they exceed the preset speed limit. This is called “violation alert strobe.” SML developed the idea and documented the development in 1999 and then found a radar display manufacturer to make the product, Applied Concepts Inc. The states offered other ideas, including a feature called “maximum speed cutoff” which, when set, will not show a speed above the preset level. SML presented the idea of “work zone alert” whereby a loud siren warns workers of an approaching excessively speeding vehicle. The states demanded large radar display numerals of at least 24" which could be seen at interstate speeds. The Iowa Department of Transportation found 18" high speed numerals were of little use at interstate speeds. They wanted large digits and high intensity amber LED lights for increased visibility. To be effective, radar displays must be seen and this visibility insures safe driver recognition and slow, not emergency, braking. The states also wanted the displays to show only speed and not other messages. The logic here is clear – you have a stop sign which only says, “Stop.”

Dr. Eric Meyer, from the University of Kansas, published the results of his study, Radar Activated Speed Displays, in late 2002. Dr. Meyer’s study found not only what the others had found in the display’s effectiveness, but it also found something new. The addition of the strobe (violation alert strobe) to the radar display “was responsible for approximately 30% of the display’s effectiveness and a display with a strobe light is substantially more effective than a display without a strobe light!” The basis and conclusions of all the research solidly says that large digit, highly visible, radar displays with strobes are the vaccine for speed control.

The Wrong Vaccine

You wouldn’t get inoculated with the smallpox vaccine to prevent the flu. You wouldn’t buy light bars for your police units which couldn’t be seen. Why would you buy a radar display which can’t be seen? The first criteria for an effective radar display is visibility. If it can’t be seen, it won’t be effective.

Here’s an incriminating (but, unfortunately true) story: A small police department bought a radar display because it was thousands of dollars less than others they had seen. They did not see it operate. The 12" high numbers were so dim they could only be seen at 200 feet. The radar was so poor, it did not report speeds until the target vehicle was 200 feet from the display. The phone calls kept coming into the chief’s office. “Why did you spend money on a radar display which can’t been seen?” The criticisms went downhill. The chief told the traffic sergeant to put large flashing amber lights on the display. His thought was that the flashing amber lights would get the drivers’ attention and they would slow down. He could have done the same thing by placing a large rock in the school zone with amber lights on it.

Researching the Cure

SML, with the assistance of the Apache Junction Police Department in Apache Junction, AZ, wanted to research the speed reduction performance of high visibility radar displays – all with strobes on a city street and a speed limit of 40 mph. There are many visibility claims by different radar display manufacturers. One claims a “visibility range of 1,000 feet or more.” SML wanted to determine the driver recognition distance of radar displays with different-sized numbers. Driver recognition distance is different than “visibility distance.” A radar display may be visible at 1,000 feet, but drivers may not recognize the displayed speed as their own. SML wanted to see at what distance drivers recognize their own displayed speed.

Driver recognition distance and driver reaction time are also different. On average, there is a three second lag between the time a driver recognizes that the radar display is showing his (or her) speed and the time it takes for him (or her) to brake and slow down. At 50 mph, a vehicle is traveling 73 feet per second (mph x 1.46 = feet per second). In the three seconds between driver recognition and driver reaction of braking, the vehicle has traveled 219 feet.

Four Models Tested

Four radar displays were used for the study: MPH’s D 25 Speed Sign with 24" numerals; RU2 Systems’ Fast 350 with 18" numerals; Stalker Radar’s SpeedBoard with 14" numerals; and RU2 Systems’ Fast 250 with 12" numerals. The RU2 and Stalker displays used 18 degree divergent LEDs, while MPH’s LED divergence was measured at 12 degrees. All radars were direction sensing which means that they would only show the speed of approaching vehicles. All were set in the maximum sensitivity (i.e., range) mode. All were slightly angled to the oncoming traffic at three degrees from center axis. The luminance of the LEDs was identical. All had “violator alert strobes” which flashed (with accompanying LEDs flashing) if the approaching vehicle exceeded the setting of 43 mph. When the vehicle slowed to 42 mph, the strobe stopped flashing (along with the flashing numerals). The displays were mounted to a DOT standard fixture next to the speed limit sign. The speed limit was 40 mph and was reduced from a 45 mph limit when the road tapered to a two lane highway. SML’s assessment van was hidden from view 1,500 feet from the radar displays. Driver recognition distance was determined by watching the brake lights of the vehicles approaching the radar displays. The exact distance was determined by shooting the braking vehicle from the rear with a Kustom Signals, Inc. ProLaser® III laser gun set to the range mode. Speed at the speed limit sign was determined by using the same laser gun, interfaced with Kustom Signals’ LaserStat program, running on a laptop computer. LaserStat automatically tabulates the traffic statistics; however, only free-flowing vehicles were measured – no platooned vehicles were assessed and no public service vehicles were included in the samples. Tabulated among the four radar displays and the baseline sample, the sample size was some 1,668 vehicles. A baseline data sample was taken without any radar display present and found only three percent of the 323 vehicles were obeying the 40 mph speed limit and had an average speed of 50.25 mph. The measurements of each display were taken at the same time in the afternoon from approximately 1:00 to 3:00.

Results

The following results clearly show two things. First, the larger the display’s numerals, the greater the distance the driver is aware of his speed and, second, the LED’s visibility is critically important in the accompanying speed reduction.

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Although the MPH D 25 display had 25" numerals, its LEDs were not as visible to drivers as the RU2 18" and Stalker 14" displays due to reduced visibility angle of MPH’s LEDs. RU2’s 12" high numeral display is not recommended at the research speed limit of 40 mph as the driver recognition distance was only 260 feet. In the three seconds it takes for drivers to brake, the vehicle approaching the 12" high display would already have travelled 219 feet and would be only 41 feet from the display if traveling at 50 mph. At speeds of 30 mph or lower, the RU2 12" is recommended. This reduced braking and reaction distance of the 12" display at 40 mph could result in emergency braking as found in previous research. The MPH, Stalker and RU2 18" high displays all provided plenty of reaction time for the approaching driver to safely adjust his speed. It is clear that high visibility LED displays with accompanying “violation alert strobes” and amber, not red, flashing numerals are extremely effective in controlling community speeds the day they are installed and a year later.

Summary

Law enforcement agencies considering radar displays – or radar trailers – for speed control should base their purchasing decisions on quantifiable effectiveness research and not on uneducated assumptions or the lowest bidder. All displays or trailers should have high intensity LEDs, “violation alert strobes,” adjustable radar sensitivity (i.e., range settings), direction sensing radar, auto dim, “max speed cutoff,” and be capable of AC or DC powering.

If you don’t take the right vaccine when selecting displays with quantifiable performance, you could contract (the sometimes fatal) “wasting the taxpayers’ dollars” disease.

For more information, contact:

1. A-T Communications www.itcpi.com

2. All Traffic Solutions www.AllTrafficSolutions.com

3. Applied Concepts, Inc. www.stalkerradar.com

4. Decatur Electronics www.decaturradar.com

5. Ingram Technologies Inc www.ingram-tech.com

6. Kustom Signals, Inc. www.kustomsignals.com

7. MPH Industries, Inc. www.mphindustries.com

8. Precision Solar Controls Inc. www.precisionsolarcontrols.com

9. RU2 Systems, Inc. www.ru2systems.com

10. 3M Company www.3M.com

11. US Traffic Corporation www.ustraffic.net n

About the Author:

Carl Fors is President of Fort Worth, TX-based Speed Measurement Laboratories Inc. and has some twenty years of radar and laser experience testing and developing public safety products. He teaches police radar and laser certification courses to federal certification standards and serves as a consultant to many municipal and state agencies. He may be reached at speed3@speedlabs.com. See www.speedlabs.com for further information.

# vehicles % at speed limit Rec Distance* Ave Speed mph over limit 10 mile pace

Baseline 323 3% 50.25 mph 10.25 mph 45-54 mph

MPH 25" 331 39% 460 feet 42.47 mph 2.47 mph 37-46 mph

RU2 18" 334 45% 524 feet 41.06 mph 1.06 mph 35-44 mph

Stalker 14" 342 41% 478 feet 42.35 mph 2.35 mph 36-45 mph

RU2 12" 338 28% 260 feet 43.82 mph 3.82 mph 39-49 mph

*driver recognition distance of radar display