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FHWA Home / Policy & Governmental Affairs / 2002 Conditions and Performance

Conditions and Performance


Status of the Nation's Highways, Bridges, and Transit:
2002 Conditions and Performance Report

Exhibit 11-29:

Year of Construction and Cumulative ADT - Deficient Steel Superstructure Bridges



Exhibit 11-29 is a bar graph that shows the year of construction and cumulative ADT for deficient steel bridges. The vertical axis measures number of bridges from 0 to 25,000 in increments of 5,000 bridges. The horizontal axis has 21 bars, one for each 5-year period between 1900 and 2000. Each bar has three parts, measuring the distribution of functionally obsolete, structurally deficient, and non-deficient steel bridges. From 1900 to 1930, anywhere from two-thirds to nine-tenths of the Nation's new steel bridges were structurally deficient with the rest split between non-deficient obsolete. From 1930 to 1950, about two-fifths of the Nation's new steel bridges were non-deficient, two-fifths were structurally deficient, and one-fifth were obsolete. After 1950 non-deficient steel bridges began to gradually disappear, from half in 1955 to three-quarters in 1970, to four-fifths in 1990, and nearly zero in 2000. The balance is split roughly evenly between obsolete and structurally deficient since 1950. There are three other items and a second vertical axis (measuring percentages from 0 to 100 in increments of 10 percent) in this chart. A line, representing the "linear" percent of deficient steel bridges for each year of construction by ADT, starts in 1900 at about 82 percent and drops in a straight line to 50 percent by 1945, 35 by 1970, 15 by 1990, and just over 0 by 2000. A series of small squares, representing the percent of deficient steel bridges for each year of construction by ADT, starts at about 65 percent, climbs to a peak of 75 percent by 1905, then drops steadily to 65 percent by 1930, 50 by 1960, 25 by 1975, and 0 by 2000. And a series of small triangles, representing the percent of deficient steel bridges for each year of construction by numbers, copies the path of the squares almost identically.
Source: National Bridge Inventory.


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