Conditions and Performance Chapter Listing

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Introduction

Summary

Road Conditions

Bridge Conditions

Transit System Conditions

Summary

Exhibit 3-1 highlights the key highway and transit statistics discussed in this chapter, and compares them with the values from the last report. The first data column contains the values reported in the 1997 C&P report, which were based on 1995 data. Where the 1995 data have been revised, updated values are shown in the second column. The third column contains comparable values, based on 1997 data.

Exhibit 3-1. Comparison of System Conditions Statistics with Those in the 1997 C&P Report

The pavement conditions reported in this chapter include all functional systems except rural minor collectors and local roads. The overall pavement conditions are presented based on the qualitative condition terms "very good," "good," "fair," "mediocre" and "poor." These ratings are derived from one of two measures: International Roughness Index (IRI) or Present Serviceability Rating (PSR). The definitions for IRI and PSR and the relationship between these two measures are discussed later in the chapter.

In 1997, 41.3 percent of measured roads were in "very good" or "good" condition, 52.1 percent were in "fair" or "mediocre" condition and 6.6 percent were in "poor" condition. Since 1995, there was a slight decrease in the percentage of miles rated "very good" or "good" and a slight increase in the percentage of miles rated "fair" or "mediocre" and "poor." Pavement condition on the Interstate system improved since 1995. The percentage of "poor" pavement on rural and urban Interstates decreased while the percentage of "very good" or "good" pavement on both rural and urban Interstates increased. Based on the NHS "acceptable ride quality" standard, Interstate pavement condition improved in both rural and urban areas.

The common indicator used to evaluate the condition of our Nation's bridges is the number of deficient bridges. There are two types of deficient bridges: structurally deficient and functionally obsolete. In 1998, 29.6 percent of our Nation's bridges were deficient. Of the total number of bridges, 16.0 percent were structurally deficient while 13.6 percent were functionally obsolete. In urban areas, 32.5 percent of bridges were deficient, while in rural areas 28.8 percent were deficient. Over half of the deficient bridges are owned by local governments.

The number of deficient bridges on our highway system has been steadily declining. Since 1995, the percentage of deficient bridges decreased from 31.4 percent to 29.6 percent. The percentage of deficient bridges on the Interstate system decreased from 24.7 percent to 21.6 percent while the percentage of deficient bridges on other arterials decreased from 27.6 percent to 25.8 percent.