The need to support heavy superimposed deck loads, coupled with the need for low-cost dock projects, led PND to research and development of a new type of dock system. While cellular sheet pile structures are common, particularly east of the Mississippi River, OPEN CELL® construction is not. New geotechnical ideas relating to soil friction were employed and tested by PND, resulting in a dock system with tremendous potential. The prototype structure was constructed in 1981 on the Tanana River at Nenana. This dock, with a 1,000-foot-long face, was built for approximately $1.5 million, as compared to an equivalent conventional dock cost of more than $5 million. Savings in excess of $20 million were recognized for the more than 30 structures built between 1981 and 1988, including docks and bridge abutments, which utilize this PND technology. Economics are derived mainly from ease of construction and use of inexpensive materials. As of June 2003, 114 OPEN CELL® structures had been constructed or were nearing completion, utilizing nearly 42,000 steel sheet piles.