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Hydroplaning hydroplane: to skim on water; especially of a vehicle : to skid on a wet surface (as pavement) because a film of water on the surface causes the tires to lose contact with it Hydroplaning can cause problems for a driver. If a vehicle does hydroplane, the ability of the driver to maintain directional control of the vehicle is severely compromised. Hydroplaning can influence the dynamic behavior of a vehicle in several ways. Under partial hydroplaning conditions (sometimes referred to as viscous hydroplaning) the tire loses partial contact with the pavement surface. This reduction in contact pressures results in an effective lowering of the friction coefficient between the tire and pavement. This condition can result in increased stopping distances and loss of control. Full dynamic hydroplaning occurs when the tire/pavement interface is unable to expel the water fast enough to allow the tire to contact the pavement surface. This condition is worsened by poor tire tread depth, a decrease in tire pressures, a decrease in the normal load or weight on the tire, higher speeds, poor pavement macrotexture and/or poor drainage from a pavement. Under full dynamic hydroplaning conditions, a driver will experience a partial to total loss of control. Often the vehicle will rotate due to differential drag forces acting on the vehicle, or the vehicle may take a ballistic, uncontrolled trajectory off the pavement surface. The researchers at CRA have extensive experience in the evaluation of roadway, environmental, vehicular and human factors to determine if hydroplaning was a causal or contributing factor in the accident.
Weather conditions can play a vital role in the occurrence of accidents and can influence not only the visibility or ability of a driver to perceive, but can also affect the dynamic performance of the vehicle. Wet pavements, snow and ice, sand and debris, and windy conditions all must be considered and evaluated to determine their probable influence on the collision scenario. The ability of an individual driver to deal with a particular weather related phenomenon is important to the accident reconstructionist.
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Visibility
Many environmental factors affect a driver's ability to perceive objects, obstructions or hazards. Rain, fog, sunlight, darkness, external lighting, and variation in object contrast are just a few of the factors which must be considered during a reconstruction. The conspicuity of pedestrians, motorcyclists, other motor vehicles, or objects is a function of contrast and illumination. To properly evaluate an event, we typically collect data to define the visibility parameters that the driver was operating under during the collision sequence. Obviously, a driver's ability to perceive and identify hazards is also a function of the human factors of that particular driver. Age, experience, eyesight, level of arousal, drug or alcohol ingestion, and medical conditions can all effect the driver's perception and response. CRA has expertise in human factors as well as visibility factors.
Accident statistics give a great deal of information about a particular collision. CRA can access Texas and National accident databases to perform inquiries or statistical analyses of collision conditions. It is possible to determine the frequency of similar accidents involving the location or vehicle make, model or type. Variables can be controlled to determine the effect of particular changes in the accident history.
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