Economy, Aesthetics and Durability

Editorial by Cliff Freyermuth, Manager, ASBI

In 1965, I made my first presentation at the four regional meetings of the AASHTO Subcommittee on Bridges and Structures (there were four regional meetings in those days) on the subject of “The Cost of the Medway Bridge if Built in the U.S.” The talk was based on applying intentionally inflated U.S. prices to the published quantities for the cast-in-place balanced cantilever Medway Bridge which had been recently completed in England.

Even with inflated U.S. prices, it appeared (to me) that the Medway Bridge with a main span of about 550 ft. would have been economically competitive in the U.S. As might have been expected, the suggestion that cast-in-place balanced cantilever concrete construction for long spans would be economical in the U.S. in 1965 was greeted with widespread skepticism. About six years later, the segmental concrete proposal for the Pine Valley Creek Bridge in California was selected on the basis of competitive bids.

An interesting current commentary on cost and aesthetics of precast balanced cantilever construction is provided in the newsletter by Frederick Gottemoeller (reprinted with permission of ASPIRE) concerning the Seattle Sound Transit Central Link.

Another perspective on both aesthetics and economy of segmental construction is provided by the enclosed brochure on the winning entries in the 2007 ASBI Bridge Award of Excellence Competition. The unit costs of $65.00 per sq. ft. for the Lee Roy Selmon Crosstown Expressway Expansion, and $120.00 per sq. ft. for the Susquehanna River Bridge are particularly noteworthy. Over the years, segmental concrete bridges have been selected for hundreds of awards, including four of the five Presidential Awards for Bridges by the National Endowment for the Arts.

The third edition of the ASBI “Survey of the Durability of Concrete Segmental Bridges” prepared by Brett Pielstick of Eisman and Russo, Inc. based on 2006 National Bridge Inventory data, is now being processed for publication, and will be distributed with the next edition of the newsletter. This survey again shows that concrete segmental bridges are performing well with time.

While the debate concerning bridge economy, aesthetics, and durability may continue for many years into the future, I am very comfortable viewing these issues from the segmental concrete perspective.