Conditions and Performance Chapter Listing

Conditions and Performance Home Page

Introduction

Background

Current Conditions and Performance

Projected Conditions and Performance in 2007

Resources Needed to Maintain and Improve the Interstate System

Addressing Interstate System Needs

Expected Rural Interstate Pavement Condition in 2007

Exhibit A-7 shows the impact that different levels of highway reconstruction and 3R investment would have on average rural interstate IRI. Note that all dollar values cited in this analysis are stated in constant 1997 dollars.

Exhibit A-7. Projected Rural Interstate Pavement Condition in 2007, for Different Possible Funding Levels

As indicated in Exhibit A-5, in 1997, all levels of government spent approximately $1.6 billion for rural Interstate roadway preservation. If this type of investment grows only by the rate of inflation over the next 10 years, cumulative investment for the 1998-2007 period would be $15.5 billion. As shown in Exhibit A-7, at this level of investment, average IRI would be expected to worsen by 23.7 percent, increasing from 93 to 115 inches per mile. This would represent a shift in average pavement condition from "good" to "fair," using the verbal descriptions shown in Exhibit A-1. Note that the average IRI values shown in Exhibit A-7 and in subsequent exhibits are weighted by VMT rather than by mileage. This approach emphasizes the impact that pavement conditions have on highway users, who bear the costs of driving on poor pavement, rather than on highway agencies, who bear the costs of repairing poor pavement. The current average IRI of 93 represents the pavement roughness that the average vehicle traveling on rural Interstate highways experiences. If current levels of investment are maintained in constant dollar terms, the percent of VMT occurring on roads with an IRI greater than or equal to 122 would increase from 18.9 percent to 37.9 percent.

As shown in Exhibit A-7, system preservation investment on rural Interstates would need to reach $21.2 billion over 10 years in order to maintain average IRI at 93 inches per mile. To prevent an increase in the percentage of VMT on roads with an IRI greater than or equal to 122 would require a cumulative investment from 1998 through 2007 of $20.2 billion. The $25.0 billion on the first line of the table represents the maximum amount that could be economically invested for rural Interstate system preservation.

Projected Pavement Conditions at Forecast Funding Levels for 1998-2007

As indicated earlier, this study projects that highway capital outlay on all functional systems will total $557.5 billion (1997 dollars) for the 10-year period from 1998 through 2007. In 1997, 3.2 percent of total highway capital outlay by all levels of government was used for system preservation on rural Interstates. If this percentage is maintained in the future, approximately $17.8 billion would be spent for rural interstate system over the next 10 years, as shown in Exhibit A-6. Based on Exhibit A-7, this level of investment would be expected to result in average IRI increasing (worsening) by 15.1 percent from 93 to 107 inches per mile, moving from the "good" to the "fair" range. The percent of VMT on roads with IRI>122 would be expected to increase to 29.9 percent. Note that the projections of 10-year capital outlay by all levels of government are based on certain simplifying assumptions about future Federal, State and local funding patterns. Federal funding beyond 2003 has yet to be determined.