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Driver Lifestyles

Avoiding Rollovers 101

By Sandy Long, staff writer
Posted Dec 10th 2012 4:41AM

We are seeing more and more rollovers now days than ever before; any sized truck can rollover in the right conditions, even sprinters and straight trucks. Why are there more rollovers these days?  It can be many things.

Without good training, a driver may think they can cheat the odds of making it around the curve. Speed limits set on curves and on/off ramps are set for cars, not load bearing vehicles. For the worst cause of rollovers there is a tie between speed and lack of training.  

Centrifugal force takes effect on curves; a vehicle is thrown to the outside of the curve if speed is too fast.  The vehicle’s tires can actually slide or skid sideways across the pavement; this intensifies on damp or icy pavement.   This can cause the driver to lose control of the steering or they over correct causing the vehicle to either flip or rollover.   Over steering can also cause the vehicle to swing down into the inner side of the curve, this inner side is called ‘the well’.

In the event of a top-heavy load or tall vehicle, when the tires lose traction even a little, it slows the speed of the tire movement while the top of the vehicle may speed up due to the centrifugal force.  This causes layover or rollover of the vehicle.

To prove to yourself that centrifugal force effects the vehicle, think about when, in your car, you took a corner; as the car went around the curve, did your body move towards the outside of the curve?   Your car felt that too, that is the effect of centrifugal force.

To take curves, one needs to ‘settle the vehicle’, this is done by lightly tapping the brakes going into the curve, going around the curve, then speeding back up as you leave the curve.  Never increase speed going into a curve.   Also, remember that bit about speed limits on curves being meant for cars, not load bearing vehicles.  You should always be at least 5 mph below the sign speed or less, depending on your load; and that brings us to the next cause of rollovers, top-heavy loads.

A top-heavy load is any cargo area with freight loaded above the halfway point to the roof, inside dimensions.  With weight high in the cargo area when cornering, the top of the trailer, or the vehicle itself, can lean to the side over-reaching the tires. This can cause the trailer or vehicle to continue tipping if centrifugal force or wind gusts are in force.

If one knows that the freight goes high in the cargo area, this usually does not enter into play as a factor as severely if the driver is properly trained.   Drop and hook situations, where the trailer is sealed when picked up, or the rare instances where doors are kept shut and then opened inside the warehouse to load then closed and sealed before the driver can see inside the cargo area, are a major factor in rollovers.  Always check your bills for cargo description; check for pallet or box count.  If the counts are too high, for instance you pull semi trailers and they loaded 60 pallets, automatically figure you are loaded high.   A good rule of thumb is to assume that the load is top heavy if you are not able to see inside to verify.

Another cause of rollover is over correcting in steering.  For instance, if you drop the steer tires off the edge of the pavement and jerk it back into line, again the tires may skid or slide sideways causing the vehicle to lean.  Turning the steering wheel too quickly also may make you have to turn the wheel quickly in the opposite direction; this can cause the vehicle to fish tail.  Combining fishtailing with the sliding or skidding tires can cause the vehicle to flip or rollover.

Always ease back up onto the pavement if you run off the edge; slowly turn the steering wheel just enough to make the maneuver.  Never brake hard, however do let your foot off the fuel pedal to slightly slow the vehicle as you maneuver back up onto the pavement.   Hold tightly onto the steering wheel when coming back up onto the pavement, depending on the height differences between the pavement and the shoulder or edge, there may be an opposing jerk as the vehicle makes the ‘jump’ up onto the pavement.

Weather can cause havoc and contributes to rollover statistics.   Usually the type of weather is ice or snow, but wind can throw a vehicle into rollover conditions.  Rain plays a part in that it intensifies the risk of hydroplaning. 

There are only two ways to combat these risks of rollover from weather.  

Slow down.
If it is so bad that you feel uncomfortable continuing on, or it is too dangerous, then park the vehicle in a safe place and let the plows work or the conditions improve.

There is one other factor in rollovers : freight shift.   When one is cornering, if the curve is taken too fast, the centrifugal force can pull loosely stacked or heavy freight to the outside of the curve inside the cargo area.  This adds weight to the side on the outside of the curve or in some instances to the inside of the curve depending on the tightness of the curve.  Since this action occurs rather quickly, it can add to the stress on the vehicle and cause the driver to lose control.  

If you are present when the load is loaded, and there is more than one pallet, make sure that the freight is properly shrink wrapped and/or secured to the pallet.  Have the loader alternate the pallets so not all of them are tight to one side or the other or leaves room between the freight and the walls of the cargo area on one side only.  Use load stars (metal grips that go under the pallet and used on wood-floored cargo areas), nail down runner wood bracing, use load locks or straps, or ask for pallets to put between groupings of pallets or along the sides if center loaded.

The one important thread throughout this article that causes rollovers is going too fast around curves.  Always remember that the second you lose by slowing down will not make you late, but if you roll a vehicle over, you might only not get your freight to the receiver, you might be dead or injured too. 

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