Accommodating cyclists signalised intersections
Figure 15 shows how a skewed intersection approach can increase the distance to clear the intersection for pedestrians and vehicles. Lane arrangements, location of channelization islands, and medians should be established to facilitate pedestrian access and the placement of signs, signals, and markings.Consideration of these “downstream” issues as part of design can optimize the operation of an intersection.On high-speed roadways with no pedestrians, it may be desirable to promote higher speeds for turning vehicles to remove turning vehicles from the through traffic stream as quickly and safely as possible.This can be accomplished with longer, smooth tapers and larger curb radii. Separation of conflict points can ease the driving task while improving both the capacity and safety at an intersection.In low-density suburban and rural areas, it may be appropriate to give priority to motor vehicle movements; however, in some urban locations, pedestrians and bicyclists at times may be the highest priority users of the road system.Figure 14 shows an intersection where double left and right turn lanes are used to facilitate high-volume turning movements. Design approaches to intersect at near right angles and merge at flat angles.The latter shows the number and type of conflicts that occur at intersections with three and four legs, respectively.The number of potential conflicts for all users increases substantially at intersections with more than four legs.
The provision of exclusive left- and right-turn lanes can improve safety by removing slower moving turning vehicles from the higher speed through traffic stream and reducing potential rear-end conflicts.Avoiding these undesirable effects can improve both the safety and capacity at an intersection. An effective intersection design promotes desirable speeds to optimize intersection safety.Figure 11 shows how pavement markings can be applied to delineate travel paths. The appropriate speed will vary based on the use, type, and location of the intersection.Geometric design has a profound influence on roadway safety; it shapes road user expectations and defines how to proceed through an intersection where many conflicts exist.In addition to safety, geometric design influences the operational performance for all road users.