§ Mr. CorbynTo ask the Secretary of State for Transport if he will examine alternatives to the use of salt, with special reference to urea, in de-icing on roads; and if he will make a statement. [11646]
§ Mr. Watts[holding answer 25 January 1996]I have asked the chief executive of the Highways Agency to write to the hon. Member.
Letter from Lawrie Haynes to Mr. Jeremy Corbyn, dated 29 January 1996
The Secretary of State for Transport has asked me to reply to your recent question asking what alternatives he has examined to the use of salt, with special reference to urea in de-icing on roads.The Highways Agency has studied the value of salt as an anti-icing agent in relation to a variety of alternatives. These have included acetate, glycol and alcohol based materials as well as urea.The studies, carried out by the Transport Research Laboratory have consistently shown that salt is a very effective anti-icing agent in virtually all conditions experienced in Britain. It also offers good value for money, even after taking account of the corrosive impact on structures.Urea is an alternative agent, although some six or seven times more expensive than salt, which is used in some areas particularly susceptible to corrosion such as the original Severn crossing and the Midland Links Viaducts where its less corrosive properties have been considered particularly important. However, it is less effective as an anti-icing agent at times of particularly low temperatures and has environmental disadvantages in so far as it oxidises when in solution with water, giving off ammonia. This ammonia can pose a considerable threat to aquatic life especially in smaller water courses.The Highways Agency remains alert to the possibility of using alternative de-icers, but at present salt remains the most effective agent giving good value for money.