vegetation. Other factors demanding consideration include community, 

 institutional, and residential values, the value of land for recreation, 

 surface-water and groundwater values, as well as fish and wildlife 

 resource values. With these values considered, roadway location can then 

 be best determined to simultaneously serve the purposes of preservation 

 of natural systems and need for urban expansion [76]. 



4.8.3 Roadways 



Location and Design : A major adverse environmental effect of highway 

 location in water areas of the coastal zone has been the replacement of 

 extensive marsh and mangrove wetland areas with the roadbed or with dredge 

 spoil mucked out for the roadbed. A second major effect is the disruption 

 of normal circulation patterns, both tidal and land drainage. A third 

 major impact is the creation of mud waves undulating out from and parallel 

 to the highway fill. These waves of mud are created by the pressure of the 

 roadbed on organic soils. Marshes over 100 yards away from roads have 

 been buckled and disrupted by mud waves. These actions have had pronounced 

 negative environmental effects on the carrying capacity of affected 

 estuaries. 



Because of the potential for the preemption and disturbance of wetlands 

 by roadways, it has become U.S. Department of Transportation policy to 

 avoid wherever feasible the drainage, filling, or interference with wet- 

 lands or the water sources supplying them [77]. Bridges and pile-supported 

 causeways can be incorporated into the design plan to reduce interference 

 with wetlands and watercourses. 



Roadways along the shoreline should be located sufficiently landward 

 of the existing beach and dune line to permit natural beach recession and 

 beachfront sand movement for the expected life of the roadway. 



Construction : The disturbances from highway construction in wetlands, 

 intertidal marshes, and other ecologically vital areas hold a great 

 potential for environmental disruption even if roadways are properly 

 designed. 



In shorelands, roadway construction, operation, and maintenance 

 activities should be controlled to prevent erosion and sedimentation, 

 obstruction of groundwater recharge, alteration of stream flow, and 

 increased pollution and eutrophication of coastal waters. 



Construction activities that need control are excavation of borrow 

 material, cuts and fills, land clearing, grading and recontouring, and 

 stream channelization or realignment. Excess fill or spoTI may be deposited 

 on marsh areas to dispose of such materials or to create a storage area for 

 heavy equipment and supplies [76][78]. Construction supply storage areas 

 should be placed above the annual flood mark, and equipment access roads 

 should be placed only in the actual roadway corridor. After construction 



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