Protecting Vulnerable Road-Users: Ensuring the Safety of Bicyclist Infrastructure for an Aging Population

Bicycling is a popular outdoor activity for people of all ages and is associated with significant health benefits. However, bicycling is also one of the most dangerous modes of travel. When involved in a collision, a bicyclist’s risk of injury or death is greater than seven times that of a motorist, and this risk increases with age: cyclists aged 65 and older face a risk three times that of cyclists in general. Implementing effective traffic countermeasures, such as bicycle lanes and shared lane markings (sharrows), can enhance the safety of both younger and older bicyclists by encouraging cyclists and motorists to behave more predictably, improving cyclist conspicuity, and encouraging motorists to give bicyclists greater leeway when passing. While past work examining the effectiveness of bicycle lanes frequently find some safety benefits after bicycle lanes are installed, these studies do not consistently find an increase in the distance at which motorists pass bicycles, sometimes finding that motorists pass at closer distances after the installation of bicycle facilities. In the current study, we examined the influence of additional factors related to the distance at which motorists pass cyclists. First, we tested whether the presence of a cyclist lane boundary line affected the accuracy of drivers’ estimates of the distance as they passed a stationary cyclist/bicycle. Second, we evaluated whether individual differences in spatial ability and processing speed among drivers predict the accuracy of passing distance estimates. Third, because participants completed parallel simulator and field versions of the passing distance task, we also compared the accuracy of passing distances in a simulated driving task to those observed in a field task for both younger and older adults, as well as examined the correspondence between individual drivers’ performance in both types of task. A total of one-hundred and sixty-two participants were tested. Main findings include 1) younger and older drivers were inaccurate in their distance estimates, but overall tended to underestimate distances (e.g., when asked to pass at 3 feet, drivers passed at much greater distances; for example an average of 4.7 feet in the field), 2) cognitive measures did not strongly predict distance judgments, 3) behavior inside and outside of the simulator were moderately correlated (e.g., for minimum passing distance, correlations between .34 and .51 for younger drivers, .39 and .67 for older drivers), and 4) processing speed of older drivers predicted passing speed outside of the simulator when a bike lane was present. From our results, it can safely be concluded that when motorists do not pass a cyclist with at least three feet of clearance, this is not due to drivers overestimating the distance between their vehicle and a cyclist.


    • English


    • Status: Completed
    • Funding: $136200.00
    • Contract Numbers:



    • Sponsor Organizations:

      Research and Innovative Technology Administration

      University Transportation Centers Program
      1200 New Jersey Avenue, SE
      Washington, DC  United States  20590
    • Project Managers:

      Tucker-Thomas, Dawn

    • Performing Organizations:

      Center for Accessibility and Safety for an Aging Population

      Florida State University
      Tallahassee, FL  United States 
    • Principal Investigators:

      Boot, Walter

    • Start Date: 20140109
    • Expected Completion Date: 0
    • Actual Completion Date: 20141223
    • Source Data: RiP Project 36864

    Subject/Index Terms

    Filing Info

    • Accession Number: 01530640
    • Record Type: Research project
    • Source Agency: Center for Accessibility and Safety for an Aging Population
    • Contract Numbers: DTRT13-G-UTC42, 03317-34695
    • Files: UTC, RIP
    • Created Date: Jul 23 2014 1:01AM