The analyses of the results of dipped headlights campaigns have been extended to include later years than those already investigated. Casualty records for Birmingham and a group of four other
large towns holding dipped headlights campaigns have been compared with those for a control group of six large towns not holding campaigns.

The data for Birmingham suggest that the increased usage of dipped headlights had (i) a beneficial effect on the number of pedestrian casualties during dark hours, (ii) a smaller adverse effect on the more numerous
non-pedestrian casualties during dark hours, and taking these two effects together, (iii) a negligible effect on total casualties during dark hours.
In the other campaign towns, where the response appears, on the whole, to have been less than in Birmingham, there was some evidence of an adverse effect casualties during dark hours.
It is concluded that the evidence is still insufficient to establish
whether the use in all lighted streets of dipped headlights (of the types currently used and with the present standard of aiming) would reduce or increase total casualties during dark hours: the indications are that with a 50 per cent usage (as achieved in
Birmingham) the change would be small. However, the effect of 100 per cent usage combined with better aiming and/or a more sharply cut-off beam might well be different.

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