Turning Restrictions:

A frequent crash type involves a collision between a bicycle and a turning motor vehicle. One scenario involves a bicyclist going straight ahead and an oncoming motorist turning left at an intersection or into a driveway. If the motorist is intent on finding a gap between oncoming motor vehicles, he or she may fail to recognize an approaching bicyclist. Another scenario involves motor vehicles turning right on red. This is a particular problem for bicycles riding against traffic.

A permissible Right Turn On Red (RTOR) was introduced in the 1970s as a fuel-saving measure and has sometimes had detrimental effects on bicycling. While the law requires motorists to come to a full stop and yield to cross-street traffic, including bicyclists (and pedestrians), before turning right on red, many motorists do not fully comply with the regulations, especially at intersections with wide turning radii. In addition, motorists are so intent in looking for traffic approaching on their left that they may not be alert to bicyclists (or pedestrians) approaching on their right. Motorists also often pull into the crosswalk area to wait for a gap in traffic, which may put them directly in the path of bicyclists (or pedestrians) crossing in the crosswalk.

In locations where there is bicycle traffic, use of signs prohibiting certain turning movements may be warranted. One example is the standard sign preventing motor vehicles from turning left, usually placed over the roadway or at a left-hand corner of the intersection. The sign may be installed adjacent to a signal face viewed by motorists in the left lane. Prohibiting RTOR should be considered as well (also with high pedestrian volumes). This can be done with a simple sign posting at the right-hand corner of the intersection. The sign may also be installed adjacent to a signal face viewed by motorists in the right lane.

There are some options that are more effective than a standard sign. For example, one option is a larger 762 mm by 914 mm (30 in by 36 in) NO TURN ON RED sign, which is more conspicuous. For areas where left and right turns are acceptable during certain times, time-of-day restrictions may be appropriate using variable-message signs.

A partial restriction may prohibit left turns except for bicycles and transit. Such signs could be used in conjunction with bicycle boulevards or other low-volume, low-speed streets to not only reduce conflicts at the intersection, but help create a preferential bicycling cross-street. Turns may also be restricted with diverters and partial diverters.