 Behavioral studies prepared for the Federal Highway Administration and the city of San Francisco have shown that streets with shared lane arrows increase separation between motor vehicles and cyclists, encourage cyclists to ride outside of the door zone, and may reduce wrong way cycling and sidewalk cycling, which are associated with increased crash risk.However, another study published in the journal Injury Prevention based on hospital records shows no statistically significant reduction in injuries, and possibly a small increase.A 2016 study commissioned by the Transportation Research Board conducted a comprehensive longitudinal analysis of census block groups in Chicago.