For a review of the subject, see Kwan I, Mapstone J.Interventions for increasing pedestrian and cyclist visibility for the prevention of death and injuries. Cochrane Database Syst Rev. 2006 Oct 18;(4):CD003438.

At one time the full article was available on the web at no cost, but that link seems to no longer exist.

CORRECTION, Google advanced search restricted to PDF files locates the entire review HERE. Dozens of studies are included in this review.