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Road Conditions

Bridge Conditions

Transit System Conditions

Bridges by Functional System

The general trend described in the previous section, where bridges in urban areas are more likely to be deficient, can also be seen in Exhibit 3-26. Bridges found on urban Interstates, urban other principal arterials and urban minor arterials have a higher percentage of deficient bridges than those on comparable rural functional systems. However, a larger percentage of bridges on local roads in rural areas are deficient (36.5 percent) compared to those in urban areas (32.6 percent).

The proportion of structurally deficient and functionally obsolete bridges varies by functional system. Exhibit 3-26 highlights some of these differences. For the most part, the percentage of bridges that are deficient increases on lower functional systems. Bridges on the Interstate have the lowest percentage of deficient bridges (16.4 percent in rural areas and 26.8 percent in urban areas). The rural Interstate bridges also have the lowest percentage of structurally deficient bridges, 4.1 percent, of all functional systems in both areas. Other principal arterials, which like Interstates account for a large share of VMT, have a relatively small percentage of deficient bridges (17.0 percent in rural areas and 33.3 percent in urban areas).

Exhibit 3-26. Bridges: Percent Deficient by Functional System, 1998

Minor arterials have a larger percentage of deficient bridges than the higher functional systems. In urban areas, minor arterials are tied with collector roads for the highest percentage of deficient bridges (38.2 percent). This is the highest percentage of deficient bridges among all functional systems. Functionally obsolete bridges make up the largest portion of this percentage.

A high percentage of bridges functionally classified as local are deficient. In urban areas the percentage is 32.6 percent and in rural areas the percentage is 36.5 percent. The high percentage in rural areas is particularly significant because 36.1 percent of all bridges are on local rural roads. In addition, a large portion of the deficient bridges are structurally deficient.

Exhibit 3-27 through Exhibit 3-30 provide a historical perspective on bridge improvements. Since 1992, the percentage of deficient bridges on Interstates, other principal arterials, collectors and local roads have decreased in both rural and urban areas. However, there was an increase in the percentage of functionally deficient bridges from 1994 to 1996. This occurred on Interstates, other arterials and collectors in both rural and urban areas. In most cases, the increase was very small. The history of local functional system roads is mixed. Even though the percentage of total deficient bridges has decreased since 1992 there was a slight increase (up .4 percentage points) between 1996 and 1998.

Exhibit 3-27. Interstate Bridge Deficiencies, 1992-1998

Exhibit 3-28. Other Arterial Bridge Deficiencies, 1992-1998

Exhibit 3-29. Collector Bridge Deficiencies, 1992-1998

Exhibit 3-30. Local Bridge Deficiencies, 1992-1998