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 and Urban Interstate Highway and Bridge Conditions and Performance in 2007

The total 10-year bridge investment levels for the rows of Exhibits A-13 and A-14 were selected to line up with their highway investment counterparts for the rows in Exhibit A-12. The top rows in Exhibits A-13 and A-14 represent the level of investment required to eliminate the current investment backlog for rural and urban Interstate bridges respectively, while the top row in Exhibit A-12 represents the maximum level of rural and urban Interstate highway investment that can be economically justified. The levels of investment required to maintain the current Interstate bridge investment backlog for rural and urban Interstates respectively were assigned to the tenth row of Exhibits A-13 and A-14 in order to line up with the tenth row of Exhibit A-12, which contains the level of investment required to maintain average IRI on rural and urban Interstates at current levels. The bridge investment levels for the remaining rows in Exhibits A-13 and A-14 were selected to be consistent with the slope of the highway investment requirement levels for the rows in Exhibit A-12.

Exhibit A-15 combines Exhibits A-12, A-13 and A-14. As described above, the rows in this table were intentionally lined up to demonstrate the relative differences between current investment levels and investment requirements for Interstate highways, rural Interstate bridges, and urban Interstate bridges. However, no analysis was performed to determine the relative benefits of Interstate highway improvements compared to Interstate bridge investments, or of rural Interstate bridge improvements compared to urban Interstate bridge improvements. Therefore, this exhibit is not intended to identify direct highway/bridge investment tradeoffs, or rural bridge/urban bridge tradeoffs.

Exhibit A-15. Projected Interstate Highway and Bridge Conditions and Performance in 2007, for Different Possible Funding Levels

Exhibit A-15 indicates that if current levels of Interstate highway investment were sustained over 10 years in constant dollar terms, and utilized in the manner recommended by HERS, average IRI could be maintained at current levels. However, if Interstate bridge investment remained constant, the Interstate bridge investment backlog would increase, especially in the case of urban Interstate bridges. Other implications of this exhibit are discussed in the next section of this study.