According the song in My Fair Lady, the rain in Spain falls mainly on the plain. Unfortunately, when the storm clouds cross over the Atlantic to America, the rain falls everywhere and, given so much of our land is covered by concrete; it tends to pool and then drain on to highways and roads before passing on through the drains and sewers to the rivers and sea. If you look at the accident statistics, rain is often blamed for accidents. The problem is that many drivers fail to realize you must approach driving differently depending on the road conditions.
Before coming to the rules, we need a little science. The surface of most roads builds up a layer of engine oil and grease during dry spells. Although this is slightly less of a problem on concrete, asphalt is slightly more absorbent and therefore holds more of the oil and grease. When rain falls, there are four effects:
• the water mixes with the deposit on the road surface making it slick, i.e. it reduces the friction and gives tires less grip;
• the rain washes particulates out of the atmosphere and adds them to the mix, i.e. the larger molecules pumped out by your gas-powered engines come down to the ground and reduce grip;
• over time, the rain will wash the surface of the road clean, but this takes between one and two hours of steady rain;
• if the rain pools on the road, it increases the risk of hydroplaning. Remember the surface of roads is usually cambered so the water will run to the sides. This make the center of the lane the safest place to drive.
Reduce your speed
When the roads are wet, you should allow more time for your journey. It’s better to arrive in one piece than to risk skidding off the road either because of the accumulated oil and grease, or because you hydroplaned. If you are approaching what looks like large pools, try to avoid them. The standing water may be hiding potholes which can damage your vehicle, your brakes will be less efficient if you get them too wet, and if the water is deep and water gets on to your vehicle’s electrical system, you will stop.
Watch out for other drivers
The advice to slow down is standard. That means the majority of other drivers are likely to reduce their speed. If you do not take this into account, you could well find yourself rear-ending vehicles. This also becomes more likely because the rain and spray thrown up by the vehicles in front reduce your visibility, No matter what you may tell yourself, it is more difficult to see through rain.
Do not brake suddenly
Although emergencies can and do arise, it’s better to slow down gently whenever possible. If the road is slick, this reduces the risk of skidding. If you are hydroplaning, slowing down by taking your foot off the gas pedal is safe. Braking is likely to send you off the road. So always increase the space between you and the vehicle in front. It’s also better not to use cruise control. Stay alert and if you feel less contact with the road, slow down without braking.