H . Chicanes ( Lane Diversion )
Another method to increase pedestrian and bicyclist safety is to employ chicanes or lane diversion along a street . Often this is done on local streets , but could be installed on major roads if engineering study results allow for this method to be installed . Shifting a travel lane has an effect on speeds , as long as the taper is not so gradual that motorists can maintain speeds . For traffic calming , the taper lengths should reflect the desired speed . Limits should be posted prior to the chicane . Chicanes create a horizontal diversion of traffic and can be gentler or more restrictive , depending on the design ( Figures 7.9.22 through 7.9.27 ).
Design Criteria :
• Provide curb extension to alter direction of traffic movement , thus reducing speed .
• Reduce posted design speeds to accommodate chicanes .
• Shift traffic alternately from side to side of the street to create an S-shaped path of travel ( Figure 7.9.22 ).
• Spacing of chicane segments depend on site considerations , driveway locations , grades of the road ( Figure 7.9.23 ).
• Bicycles can use the same path as motor vehicles ( Figure 7.9.26 ).
• When bicycles and motor vehicles use the same lane , properly sign lane as a shared path .
• Landscape plantings and islands should not obscure the driver ’ s view of traffic .
• Refer to AASHTO and City of Arlington ’ s Design Criteria Manual and Thoroughfare Development Plan for sight distance , centerline criteria , clear zones criteria , and minimum lane width standards .
• Shift on-street parking to opposite side of the street after the S-shaped path of travel ( Figure 7.9.24 ).
• Build landscaped islands ( islands can also effectively supplement the parking shift ) ( Figure 7.9.27 ).
• Refrain from installing chicanes on slopes greater than 5 %.
Figure 7.9.22 . Site plan of chicane for new installations .
Chapter 7 : Design Guidelines | 7-85