First publishedin World Highways
Winter weather often brings traffic chaos, and authorities have to be ready to tackle it as Patrick Smith reports
Good winter maintenance is rarely noticed, and it is only when things go wrong that it becomes a public issue. "When sudden bouts of cold weather bring traffic chaos, icy roads receive high-profile coverage and local authorities are criticised, often unfairly, for not affording greater protection," says the Highways Term Maintenance Association
(HTMA), the UK's top trade body for road maintenance.
With highway maintenance (like many other services) set to face severe budget cuts, the HTMA claims the private sector companies could reduce highway maintenance costs to local authorities by as much as 15%.
However, the HTMA (a group of 21 contracting and consulting companies including major international names such as Balfour Beatty
, Tarmac and infrastructure consultant Atkins
) points out that weather in the British Isles can change through extremes within the space of a day, hour or even minutes.
According to HTMA, in one winter season a typical member company operates as many as 200 gritters; uses as much as 100,000tonnes of salt; has as many as 950 people involved and covers as much as 10,000km of road network.
In order to provide an adequate winter maintenance service authorities need resources including a winter maintenance vehicle fleet fitted with snow ploughs; loading facilities or vehicles; snowblowers; enough drivers to provide 24/7 service; more use of GPS in vehicles; data loggers to monitor salt usage; decision-making staff; depots with salt stock management systems, and a system of weather stations on the network to monitor conditions.
Indeed, at a time when the UK has suffered its worst winters for years, the National Winter Service Research Group
(NWSRG/formerly the National Salt Spreading Research Group) has commissioned TRL
, which has extensive experience in all aspects of winter maintenance research and development, to produce a new Practical Guide for Winter Service. It should be ready by the end of 2010.
To prevent ice forming on roads different treatments can be used on surfaces. Generally rock salt is used although pre-wetted salt can reduce usage by about 25% and can be applied at a faster application rate and acts quicker.
A recent innovation has been the introduction of rock salt treated with agricultural by-products (ABP) or molasses. Manufacturers claim that 30% more material ends up on the road surface, rather than in verges, due to its adhesion properties, thus reducing the spread rates. There is also evidence that it is less corrosive than pure rock salt and has less effect on bridges and street furniture. Other materials effective in preventing ice forming on roads include urea, acetate and ethylene glycol, but these are less widely used as they are more expensive than rock salt, are difficult to store and require expensive plant to spread them. Konsin (produced by Univar) is particularly suited to runway deicing.
Indeed, the UK Highways Agency
, keen to replace its ageing fleet of winter service vehicles to maintain and enhance its capability to tackle ice and snow on roads, awarded a £45 million (e51.75 million), four-year rolling framework contract to Aebi Schmidt
UK and Romaquip
Irish Commercial (Sales) will supply 95 Volvo
FE snowplough/spreader chassis to both suppliers for the vehicles for the 2010/11 winter season. Aebi Schmidt and Romaquip will then fit their high-tech equipment at their factories in Birr, County Offaly, Ireland, and at Holten in Holland.
Following Aebi Schmidt's tests at its Dutch test track [a full version of the report can be found at www.worldhighways.com
], the Highways Agency can now take advantage of new technology and gain the capability to use dry and pre-wetted salt according to the forecast conditions. Dry rock salt and ABP salt will still be used, but the agency has accelerated the use, and benefits, of spreading pre-wet salt.
Meanwhile, structure specialist De Boer
, headquartered in Alkmaar, The Netherlands, is urging councils to make greater use of salt barns (potentially in partnership with neighbouring authorities) to be ready for any repeat of last winter's white-out. It claims such a move would offer greater flexibility to highways teams and enable them to switch from widely-used marine salt to cheaper rock salt, frequently shunned because of difficulty storing in the open air.