To the Editor.
—Preventing bicycle-related injuries is an interest shared by the medical, engineering, and bicycle advocacy communities. The Council on Scientific Affairs1 report offers the welcome observation that this goal can be accomplished by primary measures to prevent crashes and collisions, including educational and engineering approaches, as well as by the use of helmets to mitigate injuries incurred in crashes.One topic deserves further discussion. Twice the report recommends separation of pedestrian, bicycle, and motor vehicle traffic streams, calling it an "ideal but difficult-to-achieve engineering [approach] to injury prevention." That this separation is difficult to achieve is true, but that it is ideal is only partially correct.Separating bicyclists from pedestrians is sound engineering practice. But while it seems plausible that bicycle—motor vehicle collisions could be prevented by maximizing the separation of bicycles from motor vehicles, this is not so.2 In addition to the obvious conflicts with