ASPIRE is a quarterly magazine published by PCI in cooperation with the associations of the National Concrete Bridge Council. The editorial content focuses on the latest technology and key issues in the Concrete Bridge Industry.
Issue link: http://www.aspiremagazinebyengineers.com/i/306906
ASPIRE , Fall 2007 | 47 A E S T H E T I C S C O M M E N T A R Y by Frederick Gottemoeller This issue of ASPIRE ™ brings an embarrassment of riches to someone who likes to see improved appearance in bridges—they are all noteworthy. Spokane's Monroe Street Bridge is a particularly fne example of the sensitive reconstruction of an existing historic bridge. However, I decided to focus on the Seattle Sound Transit light rail link because it helps answer a question that I am often asked: what is the increased cost of aesthetics? The preliminary design for the rail link was quite a different structure. Based on the region's experience in the construction of highway bridges, it had been assumed that precast concrete U-shaped girders would once again offer the most economical solu- tion. After all, it is a long viaduct with many similar spans. However, that led to a design that required hammerhead pier caps at each pier and one girder for each rail track. The weight of the precast girders created construction diffculties, as did the many curves that had to be accommodated. With all of that in mind, the designer asked for and received permission to evaluate the original assumption. The result is the design now under construction. It turned out to be 15 percent less expensive than the preliminary design. It is also a more attractive design. With a single segmental box section and without the miles of hammerheads, it is much sleeker, less massive, and more transparent. The designers did an excellent job of marry- ing the piers and the girders in an attractive and structurally honest way. Finally, the piers have vertical insets that create shadow lines that minimize their apparent width. At piers near stations mirrored tiles are set in these insets to create a fash of color for users ap- proaching the structure, something that will surely be appreciated during Seattle's rainy weather. So now, when I am asked the question about the added cost of aesthetics I say, based on the Seattle Sound Transit light rail link, the cost could be less. Of course, the real answer is, it depends. If you start with a standard structure and just add decoration to it, you automatically add cost. But if you look at the problem from the ground up, consider all of the options and try to improve the structure's effciency, economy, and elegance all at the same time, you will certainly come up with a better-looking structure. You might even reap some savings. 10802_Aspire_Fall07.indb 47 8/30/07 3:16:56 PM