From Jonathan Wallace
Olaf Olsen mentions his co-worker's calculated response to a high-occupancy vehicle incentive on New York river crossings as a warning against expecting a positive outcome from measures to promote change in commuter behaviour (Letters, 4 June). We should not dismiss such schemes on the basis of a sample size of one.
The fact that the proportions of commuters using different modes of transport vary widely between cities suggests it is possible to nudge people from one mode to another, with the right combination of incentives and disincentives. The damage done to public health by air pollution from vehicles provides a strong justification for doing so.
Newcastle upon Tyne, UK
