B . Pedestrian and Bicycle Bridges
In environmentally sensitive areas where boardwalks may not be possible , such as over a wide stream , river , or roadway , building pedestrian and bicycle bridges may be the best option to continue access . Bridges may be more expensive than boardwalks , but greatly minimize impacts to the adjacent areas . Existing abandoned railroad bridges could be reused if the structural integrity is approved by an engineer .
Design Criteria :
• The bridges must conform to ADA , AASHTO , local , and state regulatory standards .
• Refer to AASHTO for information about load bearing capacity of bridges .
• Railings on bridges and boardwalks used by pedestrians to be a minimum of 42 inches high .
• Railings on bridges and boardwalks where bicyclists are present to be a minimum of 54 inches in height . The higher railing height is due to a bicyclists higher point of gravity . ( Refer to figure 7.63.5 and 7.63.6 )
• On new structures , the minimum clear width should be the same as the approach paved surface , plus a minimum of 2 feet wide on each side . The clear areas provide the opportunity to avoid conflicts between bicyclists , railings , handrails , and other bicyclists who may have stopped on the bridge .
• Prior to design of pedestrian and bicycle bridge crossing , define the floodway and floodplain elevations . This data will determine the minimum height at which the bridge decking can be constructed . The proposed bridge installation shall be verified with local government authorities prior to construction .
• Consider using prefabricated pedestrian bridges .
• Materials utilized to construct bridges should be contextually appropriate .
• Provide lighting as needed and where street lighting is not present .
Figure 7.63.5 . Example of a railing .
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