Nebraska Interlocking Bridge Blocks

Bridge replacements are an excellent opportunity to create a better passage situation for both aquatic and terrestrial organisms. However, as is the case in all construction, certain design elements either enhance or detract from the functionality for animals.

This case history has some excellent fixes for a common problem in bridge replacements. Bridge replacements often use large boulders as armament to reduce the risk of erosion at bridge abutments. Sometimes these boulders can reduce the ability of new bridges to accommodate some species of wildlife, including hoofed animals such as deer.

The image below shows a brand-new bridge with such large boulders that it would be nearly impossible for most deer to use it, even though the overall size and shape of the bridge would have made it an excellent combination deer passage and water conveyance structure.

Nebraska DOT used interlocking bridge blocks to reduce this problem. This presentation (ppt, 19.7 MB) was given at the 2013 ICOET, and the associated paper can be found in the proceedings.