To ask the Secretary of State for Transport if he will estimate the numbers of random breath tests required to detect each week (a) 1,000 drivers above twice the legal alcohol limit, (b) 1,000 drivers above the legal limit but below twice the limit, and (c) 50,000 drivers below the legal limit.

Data from the roadside surveys undertaken by the transport and road research laboratory in 1990 indicate that the following numbers of tests would be required:

• (a) 625,000
• (b) 116,000
• (c) 50,500

These surveys were carried out on Thursday, Friday and Saturday nights—the high-risk periods for drink-driving. They are, therefore, likely to underestimate the number of tests required to detect drivers over the legal limit at other times.