Assessing the impact of bicycle infrastructure on safety and operations using microsimulation and surrogate safety measures: A case study in Downtown Atlanta

This research assessed the impact of efficiently expanding the biking network in Atlanta, Georgia, using dedicated lanes for bicycles. A total of three different conditions: existing, proposed (by the authors), and alternative (suggested by the City of Atlanta) conditions were modeled to see the effectiveness of bike infrastructure design improvement and expansion. Trajectory data collected from the VISSIM simulation model was used in FHWA's Surrogate Safety Assessment Model (SSAM) to analyze the safety effect on the bike infrastructure improvement and expansion. Based on the results, both the proposed and alternative conditions resulted in safer travel through the network during the peak hour period without any apparent deterioration in delays. For instance, compared to the existing condition, the average stop delays decreased from 190 s to 164 s for the proposed and the alternative conditions. These findings showed that the introduction of bicycle lanes and narrower lanes for automobiles may not adversely affect the peak hour congestion. Also, fewer conflicts were observed in the simulated network of proposed and alternative conditions compared to existing conditions. Conflicts involving bicyclists were also reduced since the bicyclists can use their own lanes and do not have to interact with automobile traffic in the sharrows.