§ Mr. Simon HughesTo ask the Secretary of State for Transport what monitoring and evaluation Her Majesty's Government have carried out of alternatives to the use of salt for de-icing of roads and pathways; and if he will make a statement.
§ Mr. Kenneth CarlisleThe Department has commissioned the Transport Research Laboratory to conduct research into alternative de-icing chemicals—including salt with corrosion inhibitors.
The research project has the objective of assessing he performance of alternative de-icing chemicals in relation to their effectiveness as a de-icer, corrosive effect on steels and concrete, skid resistance properties, contamination of the environment, handling and storage characteristics and cost effectiveness.
The project has already assessed five principle alternative de-icers, comprising: calcium chloride, calcium magnesium acetate, urea, glycol and potassium acetate. The original project has been extended to allow completion of research on corrosion inhibitors following an American study on salt additives—commissioned by the United States strategic highways research program. An interim report is scheduled for the end of this month, with a final report due in June 1993.
§ Mr. Simon HughesTo ask the Secretary of State for Transport what information his Department has on the affect of salt used during cold weather on(a) trees, (b) grass verges and (c) concrete; what research his Department has commissioned or carried out on these matters; and if he will make a statement.
§ Mr. Kenneth CarlisleThe latest information available to the Department about the effects of de-icing salt on trees and other vegetation is contained in the Forestry Commission bulletin "De-icing Salt Damage to Trees and Shrubs", which was published in 1991. It was commissioned by the Department of the Environment and compiled in consultation with the Department of Transport's environment branch, with reference to earlier Transport and Road Research Laboratory studies on roadside vegetation and the DOT's winter maintenance statement of service and code of practice.
The Forestry Commission is now following up with a survey of salt damage to roadside trees in London, which is partially sponsored by the Department of Transport. A preliminary report has been issued and the final report is due for publication later this month and will be considered by my Department.
The Transport Research Laboratory is also currently carrying out research on alternative de-icing chemicals, as described in my reply to the hon. Member's earlier question today.
§ Mr. Simon HughesTo ask the Secretary of State for Transport if he will estimate for each of the next 10 years how much will be spent on repairing existing motorway carriages and bridges; if he will estimate what proportion of this expenditure he expects to be attributable partly or wholly to salt penetration; and if he will make a statement.
§ Mr. Kenneth CarlisleThe amounts to be spent on repairing trunk motorway carriageways and bridges will 783W depend on the funds available and the continuous reappraisal of priorities for maintenance, renewal and reconstruction in the light of the latest survey and inspection data.
There is no evidence that carriageway repairs will be required as a consequence of salt penetration, but the Department currently estimates that about £700 million will need to be spent over the 10 years from 1993–94 onwards for preventive treatment and repair of concrete bridges on motorways and all-purpose trunk roads to deal with problems associated with salt penetration. This figure could vary depending on the solutions adopted.
The work is being carried out as part of a strategic 15-year bridge rehabilitation programme which is being planned and programmed to ensure that work is carried out at the appropriate time to produce the most cost-effective solutions, and which includes assessment and strengthening of older bridges to current standards as well as work to safeguard bridges against deterioration.