An increasing amount of data suggests that common municipal investments in bicycle-specific infrastructure such as painted bike lanes and signage are a smaller component of rider safety than originally thought. Of growing importance is the theory that more riders means fewer crashes, because driver behavior is modified when cyclists have an increased presence on the street.
Elly Blue concludes that a steady stream of recent research backs the 'safety in numbers' theory, which was first identified in 2003 by public health researcher Peter Jacobsen. Looking at crash data from several communities, Jacobsen concluded that there is an inverse relationship between the quantity of cyclists in an area and the number of crashes involving cyclists.
Jacobsen theorizes that increased numbers of cyclists themselves cause people driving cars to become more aware, which thus leads to fewer collisions.
"But when there are a lot of bicyclists on the road, according to this theory, drivers take notice. They become more attentive, slow down, pass more cautiously, double-check their blind spots, expect the unexpected. They sense that the road has become a more complicated place, and adjust their behavior accordingly. As a result, the road becomes safer, presumably for everyone."