You might expect summer to be the easiest time of the year for driving, but do not be misled into thinking that there are no special hazards when the weather is warmer. As well as the special road conditions which can occur in summer, you should bear in mind that driving is more tiring on a bright day. Sunglasses are essential to reduce the strain on your eyes. Heat and the sun's glare also make you feel more sleepy, so stop to rest your eyes if you feel that your concentration and alertness start to suffer.
One of the most important aspects to remember about summer driving is that a film of dust, rubber and oil accumulates on road surfaces during dry weather. While this does not appreciably affect the grip of your tyres while the road remains dry, a summer shower can make this greasy coating almost as slippery as ice. The longer a spell without rain, the more treacherous the roads can be when rain does come, particularly at points where traffic is heavy: make sure that you are always aware of this phenomenon, but pay particular attention at roundabouts and through bends on roads where traffic is heavy. After a while this coating is washed away by rain so that the surface becomes less slippery, but take it easy all the time.
A very hot day when the sun is bright can also cause the road surface to heat up to the point where tarmac begins to melt. Improved road-building techniques have made this problem less marked than it used to be, but even so a stretch of road where the surface appears to have a sheen may well not offer as much grip as usual on a very hot day, particularly if traffic is heavy. Sometimes you see signs of the road surface breaking up on bends under the pressure of heavy lorries, so remember that grip will be reduced on this bumpy, slightly molten surface.
Summer is the time when many local authorities, seemingly with increasing frequency, decide to dress their roads with a layer of tar and stone chippings. While road signs and temporary speed limits are usually posted to warn you of this, many drivers under-estimate the hazards that such roads create if not treated circumspectly. Keep further back than normal from a vehicle in front to reduce the chances of flying chippings smashing your windscreen, keep your speed right down and be prepared for stones to be thrown up by any driver foolish enough to overtake. Since the surface is loose, it should go without saying that your car's tyres also will not grip so well on corners. After a while a newly-dressed surface begins to settle down, but even so you should remember that loose stones tend to accumulate at the edge of the road, creating a surface which is akin to driving on marbles.
The heat haze caused by hot air rising from the road's surface does not occur frequently in Britain, but take special care when considering an overtaking manoeuvre if you do see this 'shimmering' effect in the distance on a straight stretch of road. Your view of oncoming vehicles can be distorted by this illusion, giving you the wrong impression of their speed and distance.
You should clean the windscreen regularly to keep it free of the dead flies and grease which accumulate so quickly in summer. It is difficult to see through a mass of squashed flies even when it is dry, but if you have to switch on your windscreen wipers during a sudden shower you will find it virtually impossible to see through the smears. A 'screen wash' liquid added to the water in the windscreen washer reservoir will help the wipers to clear the worst of this, but even so a proper scrub is needed to do the job properly. If you are on a long journey and you find that the windscreen becomes heavily soiled, a ball of newspaper is quite effective for wiping away traffic film.
Many people like to avoid congested roads in summer by travelling at night, particularly when going on holiday. If you ever do this, make sure that you are always alert at the wheel; pay good attention to the advice on this subject contained in Driving at Night.
Although it does not usually last long, a summer shower or thunderstorm can be very heavy. If your windscreen wipers have trouble coping with the deluge, it may be wise to stop the car somewhere safely off the road and wait for the rain to ease off. Rain can fall so quickly that large puddles can form at the edge of the road, perhaps where drains are blocked; in this case, slow right down to a pace which allows you to cope if suddenly faced with several inches of water under your nearside wheels. Again, it might be sensible to stop until the rain passes and you can see properly. With visibility and tyre adhesion already reduced, there is a high risk of running off the road, or even of someone less careful than yourself running into your car.
The high humidity which accompanies summer thunderstorms can make the windows of your car mist up very quickly. Use the heated rear window and windscreen demister to keep the glass clear, and if necessary open two diagonally opposite side windows to let a draught of air through the car. Rain may come through open windows, of course, but a little discomfort is preferable to the danger of trying to drive while peering through steamed-up glass.
Every now and again rain falls so heavily that roads become flooded in dips, although this occurs more often in winter when the ground is water-logged. Floods and fords can be negotiated quite easily as long as you observe some basic rules. Your main concern will be whether you can drive through without affecting the engine; some cars can cope with more than a foot of water, but you would be stupid to try if the water is likely to reach above the base of the doors. If driving through the flood means that water will reach the bottom of the engine cooling fan, do not attempt it as the fan blades will throw water round the engine bay and drown the ignition. If you are in any doubt, it would be far more sensible to turn round and find another route.
Try to assess the depth of water from banks, hedges and even buildings. While you are wondering whether to venture through, it is quite likely that another driver, perhaps one in a vehicle with more ground clearance, will have a go; this will give you a very good idea of the depth of water. If you are convinced the water is shallow enough to be negotiated, start in first gear and keep the revs high by slipping the clutch if you have to — to prevent water entering the exhaust pipe and stifling the engine. Drive into the water slowly so that you do not create a bow wave which could force its way into the engine bay.
Despite taking all these precautions, you may still find yourself stranded because water drowns the ignition system and the engine dies. In this case you can attempt to drive the car out on the starter motor (unless your car has an automatic gearbox), although this involves ill-treatment of the engine. Simply engage first gear and keep the starter turning to propel the car slowly and jerkily forwards, stopping every 15 seconds or so to let the starter motor cool down. This will eventually get you to dry land, but you will be kicking yourself that you did not decide to turn round and find another route. There is really no point in taking any chances when for the sake of a few lost minutes you could take an alternative road, navigating by sense of direction if necessary.
Once you are clear of the flood water, waste no time in trying the brakes repeatedly and firmly while driving slowly away. Water on the surfaces of the brakes makes them virtually useless until you have dried them with a few hard jabs of the pedal. Disc brakes return to normal power quite quickly, but water lingers far longer in drums, which are used at the rear on many cars. Do drive slowly while you do this, and avoid surprising any other drivers behind you.
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