A bridge to CAR
By Justin Mayo NICAR Database Administrator
Like water under a troubled bridge.
When a bridge collapsed and killed 10 people in 1987, Jonathan Salant, then with the Syracuse Post-Standard, became interested in the subject of bridge conditions. In 1993 he completed a series titled "The Real Bridges of Madison County," which found that New York's bridge maintenance and inspection systems were insufficient.
Salant, now an AP reporter in Washington, D.C., described the inspection system and generated a list of the 10 worst bridges in New York from the National Bridge Inventory database of the U.S. Department of Transportation, which comprehensively details the condition of the nation's bridges. The Federal Highway Administration maintains and releases the database each year. NICAR has the years 1994 through 1996 and can send you the data by state or for the whole country.
The database structure is quite simple - one table with about 120 fields. Some of the information includes: location, type of structure, maintenance responsibility, owner, year built, average daily traffic, dimensions, inspection dates, and structural evaluations.
Two fields that can be used for an overall indicator of a bridge's quality are "sufficiency rating" and "status." The sufficiency rating is derived from a complex formula explained in the Recording and Coding Guide you'll receive when you order the data. Essentially, a score of 80 percent or less means the bridge probably needs some rehabilitation. A score of 50 percent or less means the bridge may need to be replaced. The status field contains a code to tell you whether the bridge is structurally deficient, functionally obsolete, or not deficient.
The scoring procedure is complicated. Although the formula for arriving at the sufficiency rating is uniform, the people and the agencies applying the formula are not. The sufficiency and status fields help to begin evaluating bridges but do not tell the whole story. When analyzing the data, Salant found that many bridges in the state had low sufficiency ratings but were not being repaired. However, he stresses that the data are only a starting point. "You really need to talk to your department of transportation folks," he said. "The data can be old and you need to make sure of the status of the bridges. Don't rely on the data too much. It will only tell you where to look."
Justin Mayo can be reached at (573) 882-0684 or by email at justin@nicar.org