Most everyone is aware that 15 passenger vans and SUVs have roll-over problems. But crash statistics show four wheel drive pick ups are just as bad, if not worse.

The problem is the high centre of gravity of these kinds of vehicles. Because the load—passengers, trees, tree carrier units—rides above the centre of gravity, the more weight the vehicle carries the more prone it is to rolling over. Every person and every tree box loaded moves the centre of gravity higher, meaning it takes less force to tip the truck over. This is the opposite to most passenger cars where drivers and their loads ride at or lower than the vehicle’s centre of gravity. In this case loading the vehicle tends to make the passenger car more stable. This is not the case for pick ups, vans, crew cabs etc. All drivers need to be aware of these design and handling characteristics of the vehicles they operate.

If you consider the usual six passengers riding in a four by four crewcab with a loaded tree-carrying unit, it is obvious this common vehicle configuration is extremely prone to rolling over. Improperly driven they may be more hazardous than a loaded 15 passenger van. Even if you have duals on the back that only adds a few inches to the axle width. The real feature that tips trucks is the high centre of gravity combined with sudden turning forces. Think of Newton’s laws of motion. This means a sudden maneuver or change in road conditions can quickly send the vehicle into a skid. Too often rolling over is the sequel to losing control in these vehicles when the vehicle suddenly “trips”. By the way if you are hauling a trailer with the configuration I just described you are, well, not safe.

Some more grim news on roll overs: they account for a very small percentage of crashes but lead to 25 per cent of crash fatalities and serious injuries. Most roll overs occur on rural or resource roads. They seldom involve other vehicles. Often passengers suffer snapped necks because of the rolling and crushing forces generated in a roll over. Unsecured passengers, cargo or pets can kill the seat-belted passengers in a roll over.

Please make all drivers aware of the limits of the vehicles they operate and the roads they drive on. In particular remind them the vehicles already come with a high centre of gravity and the more the load the more the risk of rolling over. They need to drive accordingly.

John Betts
Executive Director
Western Silvicultural Contractors’ Association