To ask the Secretary of State for Transport what the (a) life expectancy and (b) total maintenance repair costs are of (i) vehicles and equipment involved in road gritting operations using rock salt as the primary de-icing material and (ii) vehicles and equipment not involved in such operations. 
I have asked the Chief Executive of the Highways Agency, Tim Matthews, to write to the hon. Member.
Letter from Tim Matthews to Mr. Peter Robinson, dated 10 June 2003:
I have been asked by the Transport Minister, David Jamieson to reply to your recent Parliamentary Question about the life expectancy and maintenance repair costs of vehicles and equipment involved in road gritting operations and those not involved in road gritting.
The prime de-icing material used on roads in the UK is rock salt to BS 3247, or equivalent. The exception is on sensitive structures, such as the elevated sections of the Midlands Link and some bridge decks. Salt used on HA contracts has a maximum particle size of 6mm, this size being chosen as it gives a more uniform spread and readily goes into solution.
The purpose built salt. spreading vehicles designed and owned by the Highways Agency and operated by our Agents were designed with an economic life of 20 years. They were designed from the outset to be resistant to the corrosive effect of salt with special materials and protection incorporated in their design. The HA paid a premium over the cost of a standard salt spreader of 15% for these aspects.
The vehicles are maintained to standards laid down by the HA and average maintenance costs are in region of £6000.00 per annum per vehicle. The average age of the HA fleet is currently 10 years old and routine examinations demonstrate that they will fully meet their design life.
Equipment owned and operated by Agents and Local Authorities is specified to varying standards, from the lower specification type, which has a design life of 7 to 8 years to the higher specification equipment operated by some of the Design, Build, Finance and Operate companies with longer running contracts and a commercial view on reliability. Maintenance costs for the lower specification equipment cart be high due to the poor design and lack of non-corroding materials used in their construction.
The HA has no maintenance figures for vehicles not employed on other duties as these vehicles are provided by Agents.
If you would like further information Graham Rainbow at our Birmingham office would be pleased to help you. His telephone number is 0121 678 8008.
To ask the Secretary of State for Transport what his estimate is of the annual cost of corrosion on the highways maintenance budgets; and what proportion of that cost can be attributed to (a) structural maintenance and (b) repair of roads and infrastructure necessitated by corrosion from salt used for safety purposes each winter. 
Information is not held to estimate annual highway maintenance costs due to corrosion alone.There are many other causes of deterioration on structures, such as physical damage, chemical attack, water damage, weathering and general wear and tear, and sometimes they occur con currently with the corrosion mechanisms. Structures maintenance work addresses all these deterioration processes.Approximately 95 per cent. of the trunk road is made of bituminous materials where corrosion is not an issue.