Speed Studies And
 Highway Safety






    SML has long contributed its research to universities, local/state police agencies, and DOTs. It is published in many police, DOT, and public safety magazines on topics ranging from the dangers of cell phone use, comparisons of radar and laser speeds, adherence to local and state work zone speed limits, verification of the accuracy of radar detector detectors, effectiveness of speed displays in speed control, and developing products for highway safety.



Work Zone Speed Limit Compliance
    SML’s research into this topic spanned two years with speed assessments in work zones in Colorado, Ohio, Arkansas, and two Texas work zones. We used a Kustom ProLaser III tied to their laptop Kustom Signals Inc. LaserStat program to accomplish the measurement of some 4,413 vehicles.  We use laser for our speed studies as it is extremely accurate compared to road tubes or other forms of speed analysis.  An automated system like road tubes can’t see the funeral procession, the military convoy, of a lead car slowing following vehicles. Manually gaining statistics is the old fashioned way, but sometimes the old way is more accurate. Major universities use laser exclusively in assessing speeds for their research. They do this because it is accurate.

    The research found the lowest compliance with a work zone speed limit was in one Texas work zone with a speed limit of 50 mph. Only .03% of some 1,000 vehicles were traveling the posted speed limit. In the Arkansas  work zone with a posted limit of 60 mph the highest compliance was recorded of 15% of 966 vehicles. Despite efforts of “Doubling Speeding Fines” in work zones and more draconian warnings drivers, drive the speed they feel reasonable and prudent. The Texas Transportation Institute at Texas A &M University studied compliance with Doubling Speeding Fines in work zones and found almost no effect on the speed drivers drive. In an effort to reduce work zone speeds some states are now using laser/photo automated enforcement. If you are over the work zone speed limit, expect a not-to-happy ticket with your picture in the mailbox. The old fashion way of having an officer in a patrol car works best in controlling speeds. Many strategies have been tried to control work zone speed limits. Universities report their results. Aside from having a patrol car in each  work zones, radar displays get driver’s attention and they adjust their speeds accordingly.























Radar And Laser Gun Speeds
    SML testifies in may local, state, and federal courts as a court recognized expert witness in radar and laser gun development and use. This research was published in 2008 with the title of Court Acceptance Of Radar And Laser Gun Speed Readings. Seven states including Georgia, North Carolina, Virginia, Maine, Connecticut, Minnesota, and Florida recognize laser readings state-wide. This is called state judicial notice. In other states, judicial notice is granted jurisdiction by jurisdiction. In 1998 Judge Reginald Stanton of The New Jersey Superior Court asked the New Jersey State Police to compile the research using an antiquated MPH K-55 X band radar gun compared to an LTI 20/20 Marksman laser gun. Some 1,908 speed comparisons were made on the same vehicles. A radar reading was made on a vehicle and then a laser speed reading was made on the same vehicle. He concluded that only 16 comparisons varied by more than one mile per hour or .08% and accepted laser speed readings. No such published research had been conducted since that time except SML’s 2008 study. In this study, we compared some 2,648 speed readings on individual vehicles using six different laser guns and five different radar guns. In our comparison we found 99.2% of all speed comparisons on the same vehicle to be the same with .7% within +-/ 1 mph and only 1% +/- 2 mph. Judge Stanton did caution that a speed reading past 1,000 feet was questionable due to the laser beam divergence.


School Zones Safety Measures
     A considerable amount of SML’s time is spent in school zones.  There is no doubt that cell phone use causes accidents.  It is rated as the third cause of accidents and fatalities by the United States Department of Transportation only behind #1 DUI, #2 speeding, and #3 cell phone use.  Reuters in August of 2011, said cell phone use while driving accounts for 25% of all national accidents and fatalities. Slowly, cities, jurisdictions and states are addressing this highway safety issue. Unfortunately, these efforts are fragmented and oft time ineffective. Many city councils and state legislatures are banning texting while driving. They are listening to their voters who use cell phones while driving. Many of them say the law only applies to drivers under a certain age. How is a police officer to know the age of the driver or if a conversation is initiated?  These laws are unenforceable. Cell phone use while driving has become a epidemic.  What is the cure?

    SML looked at two cities enforcing a city-wide ban. on hand held cell phone use. If the officer sees a held cell phone next to the ear or being used in texting, bingo a ticket....simple enforcement. This is equated to using a seat belt and the ease the officer in seeing the offense.  Seat belt use was mandated by the United States Department of Transportation. If a state didn’t comply, they lost their federal highway funds. The USDOT did the same with legal drinking age of 21 and standardized breath alcohol levels of .08%.  Expect the USDOT to mandate standardized laws regarding cell phone use while driving.

    We looked at El Paso, TX and Las Cruces, New Mexico both  with city-wide bans on hand held cell phone use.  Of the observed 3,111 drivers, only 3.1% were on their hand held cell phone while driving.  We compared the observed percentage of 3.1% to Dallas, Fort Worth, Arlington, all in Texas, and observed 8% of 8,875 drivers were on their phones in cities without a law regarding hand held cell phone use. We noted in both samples females as a group were twice as likely to be on their phone while driving compared males.

 We next went to school zones to see how effective the use a hand held cell phone in school zones ban was progressing. It was passed in Texas in September of 2009. We went to two Dallas/Fort Worth school zones, one in Fort Worth and one in Farmers Branch. We measured the percentage of drivers on their hand held cell phones when the school zone was active and in-active.  The only difference between the two school zones was visible enforcement.  The Farmers Branch police were in each active school zone.  Officers were not present, nor visible in  Fort Worth’s school zone.  The total sample size was 3,515 vehicles.  The results were staggering. In Farmers Branch, only 2.3% of drivers were on their phone and driving compared to 7.3% in Fort Worth.  The results clearly show only with the threat of visible enforcement like we saw in Farmers Branch where hand held cell phone bans in school zones effective. Here again, in both samples female drivers as a group were twice as likely to be on their phone than the male sample.

    Another effective tool in controlling school zone speed limits is the use of mobile or permanent radar speed displays showing drivers their speed.  The radar signs must be accurate and must feature directional radar. Directional radar means the radar only shows the speed of approaching vehicles. It does not show the speeds of receding traffic. If these radar displays improperly show the speed they will be disregarded by drivers. Such radar displays must be adjustable in their reporting range. They must also be large enough to be seen by distant drivers.  The most effective radar displays will have a white strobe that flashes when a driver is over the school zone speed limit.  The digits reporting the speed should also flash until the approaching driver comes into compliance with the school zone speed limit. Many of the radar displays are permanently mounted and become active only when the school zone is active as it is wired directly into the school zone warning lights. Research with the addition of radar displays in school zones is conclusive.  Research shows speeds are dramatically and permanently controlled.  The use of radar trailers in school zones is also effective. However, many city and school district police agencies find difficulty in find a place for the use of radar trailers. In most instances, the placement of radar trailers requires additional time and effort. In many cases officers are called to more pressing situations. The USDOT is touting the cell phone’s GPS capability by turning off the cell phone above a certain speed. Research Report 0-4475-1 of the Texas Transportation Institute reports at site one “average and 85th percentile speeds reduced 8 to 10 mph with the use of speed displays.”


Radar Drones
    Radar Drones have been used successfully for many years. These fist sized radar drones transmit a police radar signal up to a mile from their location. Drivers with radar detectors think the police are ahead when their detector alerts, and slow down.  The Texas Transportation Institute at Texas A & M University in their report, Paper No. 00-1475 looked at the effectiveness of radar drones in work zones said,  “Within the work zone speeds were reduced with the radar drone. The passenger car speed reduction was significant with a 3.1 mph reduction. These reductions correspond well to previous research on radar drones. Conversations of truckers indicate most truckers use radar detectors and ‘their watch dogs were barking’ as they approached the work zone.”  In DOT applications find drones on DOT vehicles, in work zones, or where ever speed control is desired. Many radar drones are placed in school zones and uniquely on school busses. These school busses move around daily and radar detector drivers don’t know  the origin of the radar alert. Ambulances and fire apparatus mount radar drones on their vehicles to help get drivers out of their way and to warn them of their presence. Many neighborhood associations use radar drones to control speeds in their developments.


Radar Detector Detectors
    Radar detectors are legal to use in cars in all states except Virginia, Washington, D.C., and military reservations, DOD Directive 6055.4, E3. 11.3 In commercial vehicles, i.e. 18 wheelers they are illegal to use in all states as of February 1995, C.F.R. 47, parts 392, 393.71. Radar detector detectors, RDDs, have been with us for over a decade and are used to enforce radar detector bans, especially in trucks. Many cities have been given legal standing in establishing their own “commercial enforcement divisions” in enforcing federal and local restrictions on radar detector use. RDDs detect the operation of a radar detector in a vehicle.

Optical Pre-Emption
    Optical pre-emption means an emergency vehicle can change the color of a traffic control device from red to green.  They get to the emergency situation faster. Some 33,000 plus United States intersections are equipped with optical pre-emption systems.  The emergency vehicles, ambulance, fire apparatus, police car, transmits a modulated white strobe attached to their light bar to a receiver on the mast arm of the intersections to change the light from red to green.  SML along with other companies are striving to warn drivers in their cars of the emergency vehicle ahead with new technologies. The advent of forty-seven of the fifty states passing and enforcing Mover Over Laws, gives a new dimension to optical pre-emption systems. Increasingly, emergency vehicles including police units are placing optical pre-emption transmitters on their vehicles transmitting to the rear to warn approaching drivers of their presence. The optical pre-emption signals transmits up to 1/2 mile providing drivers additional warning of the emergency vehicle ahead. You can see pictured a dash mounted optical pre-emption receiver warning the driver of the emergency vehicle ahead.

    For copies of the mentioned research, e mail us at speed@speedinglimits.com or call us at 817/291-2396. Please do not contact us if you received a speeding ticket as we testify only for the prosecution. All images, text, and research are strictly controlled by the Copyright laws of the United States and the State of  Texas. Any use of the contents is only approved by the written consent of the company.








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