Congestion charging

Editor—We welcome Roberts's editorial, making the health case for the London congestion charge,¹ particularly as the revenue is required to be spent on transport. We agree that physically active transport such as walking and cycling is likely to increase. This must be monitored adequately, with attention given to changes in activity levels² and broken down by sociodemographic groups, to assess the impacts on health and inequalities.

Other potential effects of congestion charging include improvement in access for emergency vehicles. However, not all are positive: the impact of the policy will depend on which complementary measures are introduced at the same time.

Firstly, we disagree that less car travel will result in fewer crashes; this impact is difficult to predict.³ It depends whether journey times are shorter because of less time queuing at junctions or because of higher speeds. If traffic reduction is greater than was predicted, travel speeds may become substantially faster. While shorter journey times could reduce exposure to the risk of collisions, higher speeds could increase the risk by a greater amount.⁴

Secondly, congestion charging alone could adversely affect equity: road space vacated by people who are deterred by the charge could be occupied by the wealthy, who are less price sensitive.⁴

Both effects can be effectively combated by simultaneously introducing measures to reallocate road space and giving priority to buses, preferential access to disabled drivers, and effective protection to cyclists and pedestrians.⁴ This is largely true of the London congestion charge, but it is important to consider when other towns and cities follow suit.

Even London has been timid about pedestrianising road space—Soho and Covent Garden seem ideal candidates. Experience shows that whereas such schemes tend to be initially opposed by local businesses, once the schemes are implemented they benefit economically.