THE CONCRETE BRIDGE MAGAZINE

SPRING 2017

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.

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C O N C R E T E B R I D G E T E C H N O L O G Y 38 | ASPIRE Spring 2017 Mayor Ed Koch of New York City during his tenure in the 1980s famously used to ask "how are we doing?" to get feedback from his constituents. As marketing managers in the prestressed concrete industry we always want to know the same thing: are we making progress? But rather than simply ask people their opinions, I wanted to bring a more measurable analysis to this question. Since good and reliable market and trend projections rely on the appropriate selection of information, we need to ensure that sample size and design, as well as useful information items (that is, base data), are taken into account. For analyses of highway bridges, the Federal Highway Administration compiles a significant amount of data on all of the nation's bridges in the National Bridge Inventory (NBI) database, which is prepared by the states according to a standard Recording and Coding Guide. For each bridge, this results in more than 115 items that are organized on a Structure Inventory and Appraisal sheet. While the purpose of this effort is to have a "…complete and thorough inventory, so that an accurate report can be made to Congress" and to provide the data necessary to "…produce Defense Bridge and Federal Emergency Management Agency (FEMA) reports" it also contains the answer to our question. We were interested to learn from the National Bridge Inventory database the number of bridges built each year and the distribution of the total number of bridges among the various road systems (Fig. 1). We only considered bridges constructed or reconstructed after 1950. The reason for this limitation is that not all material alternatives were available prior to that time (Fig. 2). We also can see how prestressed concrete bridges, since their first use in the United States, which happened in 1950 with the Walnut Lane bridge in Philadelphia, Penn., have been playing an ever-increasing role in meeting the bridge construction needs of the public. The gains of prestressed concrete bridges become especially notable when seen as a percentage of the total bridge construction and reconstruction market (Fig. 3). Such continuous market penetration over 65 years could not happen solely on the basis of low initial costs; it must also be explained in terms of the quality and durability of this type of bridge design and construction. How Are We Doing? Learning from the National Bridge Inventory by Hank Bonstedt Figure 1. Number of bridges constructed by road system and year completed. All Figures: Hank Bonstedt. Figure 2. Number of bridges constructed by material and year completed. Figure 3. Percentage of bridges constructed by bridge type. Percentage is calculated based on the number of reported bridges completed in a given year.

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