The Relative (In)Effectiveness of Bicycle Sharrows on Ridership and Safety Outcomes

Sharrows, also known as shared lane markings, are commonly implemented in situations where planners or engineers do not wish to provide exclusive street space to bicyclists. The two primary purposes of these markings are to raise awareness of bicyclists’ presence and to move bicyclists farther toward the center of the travel lane, creating more distance between bicycles and parked cars. While past research confirmed that sharrows may effectively influence spacing, the impact on ridership and safety outcomes remains nebulous. The purpose of this research is to longitudinally examine the extent to which sharrows induce people to ride bicycles and explore the markings’ association with the number of bicyclist injuries. Census block groups in Chicago were designated as having, between a before and after period: i) either no bike infrastructure installed; ii) only sharrows installed; or iii) bike lanes installed. Statistical analysis suggests that block groups that had bike lanes installed experienced a significantly larger increase in bicycle commuters (6.46 more per block group) than block groups with sharrows (2.08) or no infrastructure installed (1.37). In terms of safety outcomes, injury crashes per year per 100 bicycle commuters decreased across the board. However, block groups that had only sharrows installed experienced a significantly smaller drop in injuries per year per 100 bicycle commuters (6.7 fewer injuries) than block groups with bike lanes (27.5) or even those with no infrastructure installed (13.5). This work raises concerns about the effectiveness of sharrows and highlights the importance of providing adequate infrastructure for bicyclists.

  • Supplemental Notes:
    • This paper was sponsored by TRB committee ANF20 Standing Committee on Bicycle Transportation. Alternate title: Relative (In)Effectiveness of Bicycle Sharrows on Ridership and Safety Outcomes
  • Corporate Authors:

    Transportation Research Board

    500 Fifth Street, NW
    Washington, DC  United States  20001
  • Authors:
    • Ferenchak, Nicholas N
    • Marshall, Wesley
  • Conference:
  • Date: 2016


  • English

Media Info

  • Media Type: Digital/other
  • Features: Figures; Maps; Photos; References; Tables;
  • Pagination: 17p
  • Monograph Title: TRB 95th Annual Meeting Compendium of Papers

Subject/Index Terms

Filing Info

  • Accession Number: 01588669
  • Record Type: Publication
  • Report/Paper Numbers: 16-5232
  • Files: TRIS, TRB, ATRI
  • Created Date: Jan 29 2016 9:25AM