Police Departments have been adding SUVs to there fleet for quite a while, but there are some people who would have you believe that if you drive a SUV you are in a rolling time bomb. Like most everything else it's a matter of perception. Looking at the numbers we find that according to NHTSA the number of occupants killed or injured in passenger vehicles has gone down but in SUVs it has gone up 1.6%, and injuries up 6.6%. Fatalities due to rollovers in SUVs have basically stayed the same (up .2%). But these statistics have to take into consideration that there are more SUVs on the road. Here is the issue: in 55% of all fatalities vehicle occupants were unrestrained - no seat belts. Police officers who drive or train with SUVs need to be aware of some basic concepts that will keep them safe.
SUV BASICS
We can start out by examining the notice you find in many SUVs, usually on the passenger side visor or in the vehicle manual. Maybe not in these exact words, but they say "Avoid turning the steering wheel sharply." That's great advice; you should never turn the wheel sharply just for the fun of it, but in the course of routine patrol there are occasions when turning the steering wheel to avoid an emergency is necessary. The message is simple: in your normal everyday police packaged vehicle at a given speed you may be able to turn the wheel quickly and sharply with no ill affect, but in a SUV at the same speed, quickness and sharpness, life could get exciting real quick.
A SCENARIO
A frequent scenario that has caused many SUV accidents (that you probably don't see in your patrol car, but I'll bet in your personal vehicle you have) is the SUV driver that is driving to close to your rear bumper. The driver of the SUV decides to pass you - but since they are driving too close - they have to put a lot of steering into the SUV in order to get around the vehicle, and that is the beginning of the problem. The driver has just done one of the most dangerous things you can do in a SUV combine speed and a lot of turning. Solution: in an SUV you need to leave yourself more room to maneuver than you do driving a regular sedan.
EVOC
If you are conducting an EVOC program with SUVs, you need to be cautious of the speeds at which you drive through the exercise; they will have to be slower. The reason for this is that the handling capability of an SUV is lower than that of standard police package vehicle. If the vehicle is a Police Packaged SUV you still need to be cautious. If you examine the Michigan State Police vehicle dynamics tests, the Police Package Tahoe has 39 more Horsepower than the standard police packaged Crown Vic, yet the Tahoe has an average speed of about 2 MPH slower through the Vehicle Dynamics Tests. (The test consist of driving the vehicles around a 2 mile race track with a long straight away) In my opinion, the reason for the slightly lower average speed in a vehicle with 39 more horsepower is that the test drivers had to slow down a bunch when they got to the corners, indicating that the handling capability of the Tahoe is much lower than that of the Crown Vic. That's what the test is for - to tell us that, although the SUV may say "police package", it does not handle the same as other passenger type police package vehicles.
WHY DO YOU HAVE TO SLOW DOWN
When the limit is reached in a passenger vehicle they tend to slide, and when they slide they will under or over steer. Look at the article "Your Vehicle Is Talking To You". In an SUV when the limit is reached they also will slide and go into an under/over steer mode. But along with sliding they tend to lift. The reason for the lifting is a simple matter of physics; the higher the center of gravity of the vehicle and the smaller the track (the distance from the center line of the left front tire to the center line of the right front tire) the more likely the SUV will lift. NHTSA calls this the Static Stability Factor (SSF) and it's what they use to determine the rollover probability of a vehicle.
A vehicle's SSF is calculated using the formula SSF=T/2H, where T is the "track width" of the vehicle and H is the "height of the center of gravity" of the vehicle. The lower the SSF number, the more likely the vehicle is to roll over in a single-vehicle crash.
A good SSF would be 1.5 while not good would be 1.1. Not good is defined as that once the vehicle starts to slide there is a 28 - 30 % chance of a rollover. For a list of SSF for various vehicles go onto the NHTSA web site.
TIRE PRESSURE AND PAYLOAD
SUVS are much more sensitive to loading and tire pressure. Consult the vehicle manual for correct tire pressure and for the payload capacity. You will more than likely find that the tire pressure will vary in accordance to the load being carried. The payload is defined as: "the combined, maximum allowable weight of cargo, occupants that the vehicle is designed to carry."
The average SUVs cargo capacity often appears to be more spacious than that in sedans and wagons. However, many SUVs have a payload capacity (how much weight they can carry) that is considerably less than what would be assumed based on the vehicle's vast cargo space. If you are driving an SUV insure that you have not exceeded the payload capacity. Once an SUV is overloaded the chance of a rollover increases dramatically.
Bottom line - when driving a police packaged SUV it is still much different than driving a standard police package vehicle; use caution.
