"Speed Kills!" goes a popular slogan intended to encourage only moderate pressure on the accelerator pedal. In the same context, wind-speed also kills: in the 20 years from 1961 to 1980, for example, over 100 drivers or their passengers were killed, and 700 injured, on British roads as a direct result of storm force winds. It is safe to assume that Irish motorists do not escape unscathed.
Strong winds can affect road traffic in a variety of ways. In the most obvious sense they make a motor vehicle difficult to steer, and may even overturn it. But a common associated hazard is that roads may unexpectedly be blocked by fallen trees or obstructed by windblown debris from buildings or other structures.
Motorway bridges, too, can be dangerously weakened by a storm, and - less commonly in this country - snow or sand blown onto a thoroughfare can affect the safe flow of vehicular traffic.
Problems of control increase dramatically with rising wind strength. The force exerted on a vehicle by a crosswind is proportional to the square of the wind strength, which means that if the wind speed doubles from, say, 15 to 30 m.p.h., the pressure exerted on a vehicle by a crosswind becomes four times what it was before.
The force exerted is also proportional to the area of a vehicle presented to the wind. As one would expect, therefore, high-sided lorries, double-deck buses and caravans are in danger at much lower wind speeds than those which might pose problems for the family car.
Measures to reduce the adverse effects of strong crosswinds include the construction of artificial windbreaks or the planting of trees along exposed stretches of a highway. These are often successful, and have the added benefit of reducing motorway noise in the vicinity. But they can also be counterproductive.
Two parallel lines of trees, for example, may funnel a wind from certain directions, causing it to blow more strongly than elsewhere, or the trees may blow down and obstruct the highway they were planted to protect. More importantly, perhaps, any windbreak may leave drivers unprepared for a sudden increase in wind strength at the end of the protected sector.
Fixed signs indicating susceptibility to crosswinds have been found to have limited impact because they tend, over time, to become a familiar feature of the landscape, and may therefore be ignored. Illuminated warning signs are more expensive, but also more effective, as they appear only when real danger threatens and can also give an indication of how severe the problem at the time may be.