Since the invention of RADAR in the late 1930’s it has been used for a great many different purposes, the military uses radar in some way or other every day, commercial airlines, private aviation  and nearly any function requiring a high degree of accuracy when measuring speed and distance.

Radar has been used in law enforcement for many years primarily in speed enforcement.  It can be safer to use in some cases since it does not require pursuit, pacing and stopping in unsafe locations.  It can accurately record speeds to confirm complaints by citizens and document areas that need review for possible design problems with the roadway.

Radar is really an extremely complicated simple device.  Complicated because most folks including those who use it are not aware of exactly how it works.  For purposes if this document we will try to keep it simple.  A radar emits a beam (star trek) out into space until something (a car) is caught in the beam which is then reflected back to the radar unit.  This electronic marvel then calculates exactly how fast that car is going and displays the result on a small screen.

I know that many of you have seen the pictures of a police officer sitting in his car with his wife’s hair dryer sticking out the window, don’t knock it, it works but does not tell anyone the speed and will not even dry your hair unless plugged in.

Why do we use radar?

We have all heard that speed kills, that is true.  A car hitting a solid object at 40 mph will kill the occupants of the vehicle in 4/10 of a second.  At 80 mph it still takes the human body 4/10 of a second to die.

It would be more accurate to say that traffic violations of all kinds cause accidents and the damage and/or injuries caused are primarily the result of speed.  The higher the speed the more severe the injuries.

Speed is regulated due to several factors; the design of the roadway, the width, surface, line of sight, curvature and existing hazards.  Another prime factor is the reasonableness of those persons driving on the roadway.

One of the factors governing speed is called the 85th Percentile.  This means the actual measured speed that is driven by 85% of the drivers who are assumed to be reasonable and prudent.  Other factors such as school zones, residential and commercial areas are set by regulation just like freeways are set for certain limits.

No, that does not mean you can get all your neighbors together and drive 50 mph up and down your residential street to get the limit raised.

In this day and age radar has become a great deterrent to speed.  It will not stop you or cite you but just a radar unit sitting on the side of the road telling you how fast you are going is a great aid but usually for those drivers who are not paying attention to their driving or speed.


There are two basic systems of traffic enforcement POSITIVE and NEGATIVE.

Let’s consider a scenario.  A driver is driving on a semi-rural residential road posted at 25 mph.  A Deputy observes him driving at a speed that the deputy feels is a bit fast for the area and roadway.  It is raining lightly, a school bus passed about five minutes before going the same direction, there are many curves in the road and the driver is turning his head to the right conversing with his passenger.

The deputy confirms that the driver is driving 35 mph in the 25 mph zone in inclement weather and there could be school children further up the road being dropped off.

He activates his lights and follows the car for a half mile before the driver recognizes he is being stopped and pulls over.

When the Deputy advises the driver he was driving 35 mph in a 25 mph zone the driver adamantly denies doing so.  When the deputy advises the violation was recorded by radar, whoops!  Two chances that the radar doesn’t work properly, slim and none.

Now comes the POSITIVE or NEGATIVE enforcement decision.

What are the chances that the driver will benefit from this contact?  What is his past record, what is his attitude, was there an accident, near accident, did he lose control, his wife has been reading him the riot act for the last five minutes.

Writing a citation is Negative Enforcement.  Warning the driver is Positive Enforcement.  What is best for the community?

Whether or not a citizen is given a citation is primarily left to the judgement of the officer.

If for instance the citizen is rude and offensive, this does not mean that the officer is offended by these actions but if he cannot get through to the citizen the need to modify his/her behavior and driving skills, maybe that is best handled by a judge.

The vast majority of officers if asked will recommend that when stopped the driver and occupants of the vehicle just be themselves listen carefully and above all be courteous and polite.  The officer is not a judge he is merely documenting a violation that could be heard in a court of law.


The vast majority of police officers are above average drivers.  Consider the reasons for this; they drive under all conditions both day and night, regardless of weather, traffic and hazards.

While every minute of every day is not filled with danger they do very frequently go from one extreme, complete boredom to emergency response to many very dangerous situations in seconds.  There is a tremendous adrenaline rush in some cases especially when a child is involved.

Their first objective is always to get there safely,

Where is ‘There’.  Even though they spend many hours memorizing the names and locations of streets and common locations it could be the first time they have worked this beat.

Regular patrolling vs Emergency Response

Is there a difference?

Not Really!

Whether on routine patrol or in response to an emergency you still have to get there, alive.  The route must be planned out, are shortcuts really shortcuts (not really)?

When learning to drive most of you were taught to drive a distance ahead of your vehicle, meaning that you should be looking for hazards, traffic, pedestrians a block or so down the street.

Police Officers were taught the same basic technique except they were taught to think a quarter mile, half mile or even two or three miles ahead of them,  Where are the dangerous corners, blind intersections, commercial businesses with numerous customers coming and going, taverns with possibly intoxicated drivers coming and going.  These situations are those considered constantly while pushing that iron horse.  Where to the deer frequently cross?  What are the favorite roads for cyclists?


Most of you have experienced a period of time while driving that took your complete concentration and attention and even then you were not completely comfortable.

Let’s consider an officer in a patrol car with both front windows down so he/she can hear better, listening to a radio, many of which have multiple frequencies and then in addition to all the regular knobs and buttons they put in cars you also have a whole bunch more for emergency lights, flashing warning lights, siren (some with three or four different sounds) a computer, your brief case loaded with forms, a ticket book, Clip board, your lunch, thermos bottle, jacket, first aid kit, axe, rope, flares, traffic cones, fire extinguisher and a shovel.

There are many things to consider whether on routine patrol or when responding to a call and all require concentration and your undivided attention directed toward you’re driving and the safety of all around you.  Will that slow driver in front of you panic and stop right in the middle of the road right in front of you?  It happens, far too frequently!  Dogs, cats, deer, and kids they all run out into the street at the most inopportune times.

Why am I telling you these things?  Because this is how safe emergency responders learn.  The Field Training Officers are constantly putting them through these scenarios instilling the knowledge that makes them better and safer drivers.

Do you as a licensed driver need to know all this stuff?  If it makes you a better driver, why not!  A fifty percent improvement in situational awareness will increase your personal safety factor tremendously but it is work, it takes practice and repetition.

The life you save with your knowledge may be that of a member of your family.

You may have noticed by now that I have not made any reference to all the laws governing the operation of a motor vehicle on a street or highway.  Why?  Because you already know that material, you passed the test to get your driver’s license and more than likely have driven for a period of time.  This experience in itself makes a great many people think that they are the world’s greatest and safest drivers.  If that is true, why did over thirty thousand of our citizens die in traffic accidents last year and hundreds of thousands more suffer injuries? The deaths alone are more than the entire population of Jefferson County.

The vast majority of the drivers in this country know what a speed limit sign means, just like they know to stop for a stop sign.  This brings up an interesting point.  What does the word STOP really mean?  Last time I checked STOP meant a complete absence of motion.  It is a time for reflection, is there any traffic coming from the left?  Is there any traffic coming from the right?  Are there any pedestrians on the sidewalk at the corner?  Can I see an adequate distance both left and right to determine if a car, bicyclist, pedestrian is approaching?  One last look to the left and another to the right and pull out safely.

Failure to stop for a stop sign is probably the most commonly violated traffic law in existence.  Most stop sign violations are for speeds of 5 to 10 mph as they pass the stop sign and the majority of the drivers freely admit to not making a COMPLETE STOP.  It is a hazardous violation good for one point on your driver’s license for three years.

What is CO-EFFICIENT OF FRICTION and why do I have to remember this?

Some of you have had this experience during your driving lives.  You are driving on a wet street or icy snow covered street and you put on the brakes and the car does not slow down, you turn the steering wheel and the car continues to go straight. Humm?

There is a direct relation between the surface of the roadway and the tires on the car commonly referred to as the co-efficient of friction.  If the roadway is nice new concrete or asphalt and your tires are in good shape the car should come to a stop when you apply the brakes.  The smoother the surface of the road, ice, snow, sand, oil, etc. the more slippery it is and the lower the co-efficient of friction.  I know, slicks on race cars are bald and the track smooth and they have lots of friction when accelerating.  Very high co-efficient of friction but then they are unsafe for use on streets and highways!

Good clean well maintained dry streets and highways with good tires on your car will give you a co-efficient of friction of about a .07  if the street is wet it could go down to a .05.  Wet streets, slow down.

Cruise Control in the rain?

Do NOT use cruise control in the rain.  If the tires loose traction the cruise control system may try to override the lack of traction and accelerate causing a loss of control.

Rear View Mirrors are not for applying makeup while driving.


  1. Adjust your seat.  Your left leg when straightened should allow you to position your left foot flat on the floor and slightly push your fanny back into the seat.  Your left foot on the floor will keep you firmly in the seat in the event of sudden movement. Place your hands on the steering wheel in the ten o’clock and two o’clock positions.
  2. Adjust your rear view mirror, again.  Sometimes they sneak into different positions on their own.
  3. Check and adjust your side view mirrors, both sides, you should be able to see a little bit of the sides of your car and clearly to the rear.  Don’t move around while you are adjusting them.
  4. Check all around your car, front, sides and rear for loose kids, dogs, Sasquatch or bicycles.
  5.  Make sure the cell phone is turned off!
  6. Start the car.
  7. After you have backed out of the garage or are getting ready to merge with traffic.  Think; let’s try driving today as though you have a hard-boiled egg between your right foot and the accelerator pedal, nice and smooth.  Maybe tomorrow we will try a raw egg!


Driving is a privilege NOT a right!

Will reading these few pages make you a better driver? NO!

Will thinking and applying some of the techniques discussed and a few of the tips help you to become a better driver? YES!

But you must practice all of them diligently and apply your concentration and attention to the job at hand, controlling a vehicle weighing thousands of pounds in a safe manner not only for you but also for all the others using our streets and roadways.

Is this all there is to it? NO!

Emergency responders constantly evaluate their abilities and look for ways to improve their skills.  Some learn and practice techniques on a Skid Pan of soapy water or sand and gravel, learn how to make those crazy turns that they do on TV and actually drive on a race track.  Not all officers have the desires to take their driving skills that far but those that do, try to teach what they have learned to those just starting out.

Stay tuned for the next chapter!

Doug Henderson, Retired Sergeant
San Diego Police Department
San Diego County Sheriff’s Department