Flooding & Runoff
Even though the temperatures don’t really feel like spring, the calendar says it has arrived. With April just around the corner, it won’t be long until our area will be in line for showers, rain, maybe even thunderstorms and certainly lots of water from snow melting in the higher elevations. Every year it seems we hear stories, often tragic, about someone being swept into a stream or river and drowning. I thought it might be good to review some safety tips concerning how heavy rains and fast moving water effect how we should drive our vehicles.
We are all familiar with the term hydroplaning. That’s what happens to a car when we drive too fast in the rain or on wet pavement. Because of our speed, the tires are unable to expel the water and a film of water builds up under the tires causing the car to “float” over the road surface. When that happens, the steering feels light and you can’t control the car. The solution is to simply let off on the accelerator and let the car settle back onto the pavement. Breaking or trying to steer may result in a skid you won’t be able to control.
Another situation often encountered from rains or runoff is flooded roadways. A small urban stream can cause flash flooding in less than an hour from heavy rainfall. As little as one foot of water on the road, especially if it’s moving rapidly, can move most cars off the road. Six inches of fast moving water can easily sweep a person off their feet. If you drive through a flooded roadway and water splashes onto your engine components, you can stall and be in trouble.
There are a lot of tips for navigating flooded roads such as stopping to check the depth of the water before entering, staying in the center of the road where it’s higher, keeping the engine RPMs up so you don’t suck water into the engine etc. The best advice, however, is that if you can’t see the painted lines on the road, do not try to drive through the water.
Moving water is especially dangerous because it exerts pressure on the vehicle that can easily overcome other pressures acting on the car. The deeper the water and the faster the flow, the greater are the forces acting upon the vehicle trying to cross the stream. Forces acting to keep the car on the road include the weight of the car and the friction of the tires on the ground. Forces acting to move the car sideways include the force of the stream and the buoyancy of the water. When stream flow and buoyancy overcome friction and weight, off you go. Don’t think that because you drive a big, heavy SUV you’re safe. Their larger size and bigger tires tend to make them more buoyant than smaller cars and even more prone to being swept away.
Sometimes driving on wet roads can be just as challenging as driving on snow and ice. Slow down on wet roads and use extreme caution when crossing streams or standing water on the road.