Decision Tree–Based Method for Safety Treatment Selection at Intersections Involving Shared-Use Low-Volume Roads

Users of nonmotorized transportation often travel along low-volume roads in rural, recreational settings. These users thus share the low-volume road with vehicular traffic. In such cases, safety issues pertaining to these users, particularly bicyclists, usually arise at crossings where the shared-use low-volume road intersects with another roadway. Shared-use low-volume roads demonstrate operational characteristics similar to those of trails, so many available safety treatments for trail–roadway crossings can be borrowed to apply to intersections involving a shared-use low-volume road. This study focused on developing a systematic treatment selection mechanism to address the safety of users of nonmotorized transportation at such intersections. This mechanism first synthesized the best practices of safety treatments for trail crossings and selected appropriate treatments to include in a pool of treatments that can also be applied to intersections involving shared-use low-volume roads. Second, a decision tree–based treatment selection method was developed to facilitate traffic engineers' selection of suitable treatments from the treatment pool. Each end node of the tree leads to a customized treatment toolbox that contains only those treatments suitable for the specific volume, speed, and lane settings of the study intersection. The decision tree–based method simplifies the treatment selection process and in turn helps professionals substantially save time and increase reliability in their selection of safety treatments for a given intersection involving a shared-use low-volume road. A case study is introduced to demonstrate the benefit of using the decision tree for proposed safety treatments at an intersection involving a shared-use low-volume road.