Bicycle Safety Guide and Countermeasure Selection System
Adding medians and consolidating driveways to manage access. Illustration by Michele Weisbart, Model Design Manual for Living Streets
Consideration for bicyclists' needs should cover from the trip origin to the destination. Every driveway and street connection is a potential conflict point among motorists, bicyclists, and pedestrians. Therefore, managing the number, spacing, access, directional flow, and other aspects of driveway and side street connections protects those traveling along the corridor from conflicts with those entering or leaving the corridor.
Driveway design affects sight distance for both motorists and bicyclists accessing roadways, as well as the speed and perhaps care with which drivers enter or leave the roadway. Several driveway design characteristics may cause safety and access problems for bicyclists, including driveways with large turning radii, multiple adjacent driveways, driveways that are not well defined, and driveways where motorist attention is focused on finding a gap in congested traffic.
Examples of driveway improvements include narrowing driveways, tightening turning radii, and improving driveway definition. Smaller driveway radii of 15 to 20 feet are most compatible with bicyclist movements because motorists have to slow down to complete the turn. However, the presence of on-street parking and bike lanes can increase the effective driveway radius, so care should be taken to consider these factors when selecting a radius.
Closing (consolidating) driveways or converting driveways to right-in-right-out are additional design strategies to reduce the number of conflict points with bicyclists. The trade-off is between providing direct access and promoting through movement. For example, the main purpose of freeways and arterials is to move through traffic, and access should be restricted to necessary interchanges. Local streets should generally serve all destinations and access should not be limited.
Stop bars, signs, and other measures may be useful at commercial driveways, but sight distance should not be impaired with too many or improperly-placed signs. Driveway rights-of-way should also be kept cleared of foliage and other objects that obscure visibility.
Driveway improvements provide good visibility for motorists and bicyclists accessing the roadway and reduce conflicts between those traveling along the corridor and those entering or leaving the corridor. They slow motor vehicles entering/exiting the roadway and establish pedestrian right-of-way. They also reduce the chances of a bicycle-only fall or turning error when bicycles enter or leave the roadway.
No additional costs when incorporated into original plan and construction.
Authors and Acknowledgements