Letter: Jostling for space on the towpath

Sir: John Redwood thinks that increasing speed limits will improve traffic flow into built-up areas. It can be shown very simply and surprisingly (assuming 15ft long cars and the interpolated thinking and braking distances found in the Highway Code) that the maximum traffic flow (number of cars per second) is obtained when all cars travel at 17mph. The answer is therefore to reduce speed limits, not increase them.

Dr STEPHEN N DANCER

Derby