IV-128 



The advent of nuclear powered ships has presented additional prob- 

 lems. The harbor areas must be protected from every possibility 

 of environmental contamination by radioactive substances, and 

 these ships must have easy access to the sea. 



The use of the harbors for waterborne transportation is competitive 

 in that it may cause other uses to be foregone. Heavy ship traffic 

 interferes with pleasure boating and related activities (Figure IV. 

 2.17). Maintenance of the ship channels may alter the ecology and 

 the surface area occupied by the large vessels may well interfere 

 with safe pleasure boating. 



Transportation in estuaries is not limited to waterborne traffic. 

 Since a major percentage of large cities are located on estuarine 

 systems, there is considerable pressure to develop fill areas for 

 airports which then utilize the long overwater approaches to keep 

 the jet noise away from developed areas. San Francisco International 

 Airport is a good example, and in Washington, D.C., National Airport 

 uses fill areas and overwater approaches (Figure IV. 2. 18). 



As the airplanes get bigger and the air traffic gets heavier, it 

 appears that more cities will try to develop isolated airport facil- 

 ities. The planning of the Miami Jetport in the Big Cypress Swamp 

 is a good example. In cities where estuarine areas are available 

 a similar trend will probably develop. The last aspect of trans- 



