Sunday, 30 December 2012

Motorway spray

Motorway spray

Having driven three long journeys in a matter of days, often in very heavy rain, it became apparent that motorway spray was not all it seems.

There are few worse hazards with visibility being significantly reduced. It is particularly bad as large vehicles are overtaken. There is a critical amount of rainfall for spray to be a serious problem. Drizzle and light rain are a nuisance but tolerable.  Steady heavy rain over a couple of hours builds up large flat puddles. Aquaplaning becomes more likely. Experiencing torrential downpours earlier in the year was unpleasant too. At least the ominous black clouds ahead gave advance warning. Even so the impression of driving into a waterfall was disconcerting with rapid braking by most, but not all, on the road.

 The nature of the road surface makes a huge difference too. On the M25 (thankfully not very busy) there were patches where spray was everywhere and then a hundred yards further on there was little, despite the rainfall being constant. A more mottled surface seemed to absorb moisture and had less surface-water. One of the worst stretches was on a new motorway - the M74 extension in Glasgow. This is barely 18 months old and the surface is slick and even - and extremely wet. Speeds were relatively low yet the amount of spray was significantly more than a few miles back. It is clearly possible to design roads - and motorways in particular - to deal with copious amounts of water. So what is going wrong? Is there some sort of compromise with traction and wear? Is it good old cost-cutting?

Finally there are a minority who share the Indian faith in karma. They do not adjust their speed to the conditions. And/or they do not turn their lights on. Hard to believe but true. 

Would such numpties show up on the proposed ‘black box’ scheme to reward safer driving by cheaper insurance bills?

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