To test common risky bicycling situations with cars, we conducted a driving simulation study using the world renowned National Advanced Driving Simulator. We identified such situations from previous research and also by analyzing our PedalPortal naturalistic bicycling dataset, which contains real-world bicycling video and GPS data from children and adults. The situations included (see graphics):
- Overtaking in the presence and absence of shared lane arrow markings
- Right turn across path
- Bicycle path mid-block crossing
Summary of what we found: Shared lane arrows were beneficial, compared to no shared lane arrows, and age was an important factor related to wait time, speed, and braking when a driver encountered the different bicycling events we tested. Overall, this study shows how simulation is a valuable tool for studying driver responses to bicyclists.
Results from our study showed that the presence of shared lane arrow markings (also called sharrows) increased the separation distance drivers gave to bicyclists. We also found that older drivers gave less passing separation distance to bicyclists than drivers aged 26 to 40, but only when there were no shared lane arrow markings present. The majority (>80%) of drivers in the study did not make a complete lane change to pass the bicyclist, regardless of whether or not shared lane arrow marking were present.
In our the right turn across path (right-hook) event, we found that older drivers had higher average speeds and higher minimum speeds, and less wait time for the bicyclist to pass, compared to younger drivers. With this finding, it was unclear whether this difference was due to less patience or more precise timing among older drivers.
Bicycle paths often have mid-block crossings and crossings with visual obstructions, like bushes or fences, as they weave through residential areas. In the mid-block bicycle path event we tested, which included a visual obstruction, we did not find any significant differences by age or gender in how drivers responded to the bicyclist.
This study was funded by the SaferSim University Transportation Center.