Comité asesor

The degree of disruption caused by a particular snowfall is determined by two main sets of factors: (a) the physical nature of the fall, including snow depth and duration and the associated meteorological conditions such as wind speed which may cause drifting, and the nature of the snow; and (b) the state of preparedness of the community and the individual—this will be affected by the frequency with which heavy snowfalls are perceived to occur, and the investment of capital in snowclearing operations.

It may seem surprising that major road dislocation can, from time to time, affect a country like the UK where local-authority road-clearing departments are relatively well equipped and organised. Perry and Symons (1980) have described the blizzards in northern and eastern Scotland in January 1978 which paralysed the region, trapping several hundred cars in deep snowdrifts and necessitating an airborne rescue operation to rescue trapped drivers. Six years later, in 1984, level snow depths of 50–60 cm, with deep drifts, again caused blocked roads and prolonged disruption of communications in the Highlands of Scotland.

Traffic disruption from the snow hazard in the UK

The winter maintenance of highways 3 4

Snow gates have now been installed on several roads. One of the main advantages that they confer is that, if vehicles can be prevented from entering and becoming snowed-up on difficult stretches of road like the Drumochter Pass on the main A9 routeway, snow-clearing operations can be carried out unhampered, but there has been local community resistance to their installation.

Although heavy falls of snow are less frequent further south over England and Wales than in Scotland, their impact in densely populated areas can be even more disruptive. Table 2.1 shows the nature that disruption can take with different amounts of snow lying. While in the countryside snow can be blown from fields to fill narrow roads and lanes which act as natural receptacles, in towns, city streets may require not only clearing but also snow hauling to open spaces since the physical space to dump cleared snow is often not available (Perry 1981).

The paralysis which followed severe blizzards in Wales and South-West England in both 1978 and 1982 highlighted the importance of road communications even in the depth of the country where commercial dairy farming is dependent on regular, efficient transport of milk from the farms. When this becomes impossible thousands of gallons of milk may have to be poured away, leading to considerable financial loss. It is estimated that in 1990 there were over 700 000 heavy and more than two million light goods vehicles on Britain’s roads.

Even a few days’ disruption to a significant part of this fleet results in the total bill to the economy running into millions of pounds. Not surprisingly it is costeffective to invest heavily in plant to clear roads as quickly as possible, even though for the fast removal of deep snow, self-propelled snow blowers, costing over £100000 each, are essential.

Twenty-four-hour working on snow clearance of the Primary Route Network (about 15% of the total road mileage) will be started once severe conditions develop. Not surprisingly expenditure on winter maintenance can be a significant part of total highway expenditure: in the Highlands of Scotland it constitutes 25% of the total road budget. In January 1987, in Kent, the highway authority mobilized 10 000 items of plant and was spending £5 million a day (Manson, 1987). As Figure 2.2 shows, in a typical lowland England county like Essex, expenditure is highly variable from year to year, depending on individual winter severity.

Those responsible for the transport systems are not judged by what resources or effort they put in but what they achieve in respect of keeping transport systems operating. Local authorities in England and Wales spend around £100 million a year on salting and snow-clearing operations (Figure 2.3) with winter maintenance accounting for 8.5% of the total highways maintenance expenditure (Audit Commission 1988).

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Although we could probably buy our way out of winter chaos in a country like Britain, the cost would be extremely high. The question for the community at large is are we willing to do so?

Traffic disruption from the snow hazard in the UK Table 2.1 A hierarchy of disruption due to snow and ice in the British Isles

The winter maintenance of highways 3 6

Figure 2.2 Annual winter maintenance expenditure in Essex for the period 1975–1987, and mean January temperature. Expenditure varies considerably, depending on winter severity.

Figure 2.3 Snow cleaning operations in city streets in progress.

References 3 7

2.5 REFERENCES

Audit commission (1988). Improving Highway Maintenance. London: HMSO.

Collier, C.G. and Chapuis, M. (eds) (1990). Weather Radar Networking. Seminar in COST Project 73, Dordrecht, Kluwer, for Commission of European Communities.

Gardner, D. (1987). Winter chaos—can we buy our way out of it? Introductory notes to conference on Winter Chaos, pp. 12–16. London: Institution of Civil Engineers.

Manson, J. (1987). Counting the cost of Britain’s big freeze. Highways, 41–42.

Perry, A.H. (1981). Environmental hazards in the British Isles. London: George Allen

& Unwin.

Perry, A.H. and Symons, L (1980). Economic and social disruption arising from the snowfall hazard in Scotland—the example of January 1978, Scot. Geog.

Mag., 96, 20–25.

Perry, A.H., Symons, L. and Symons, A. (1986). Winter road sense. Geographical Magazine, 58, 628–631.

Ponting.M. (1984). Weather prediction systems. Highways & Transportation, 31, 24–32.

Symons, L. (1980). The economic and social disruption arising from the snowfall hazard in Scotland—the example of January 1978. Scottish Geographical Magazine, 96, 20–25.