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
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Projected Conditions
and Performance in 2007
The future condition of the Interstate system is a function of several
factors, including the current condition of the system, projected travel
growth, and the level of future investment. This study uses current condition
data, performance data, and travel growth projections from the Highway
Performance Monitoring System (HPMS) database to predict what impact different
levels of investment over the 10-year period from 1998 through 2007 would have
on the Interstate system. Data from the National Bridge Inventory are used to
project future Interstate Bridge conditions.
Since rural and urban Interstate data are available, and the characteristics
of rural and urban Interstate routes are different, this study examines them
separately. Investment requirements for highway preservation, bridge
preservation and system expansion are separately identified, to facilitate more
detailed analysis of physical conditions separate from operational performance.
This section includes nine analyses of projected Interstate conditions and
performance. The first examines the impact that different levels of investment
for highway reconstruction and 3R (restoration, rehabilitation, and
resurfacing) would be expected to have on rural Interstate pavement conditions.
The second analysis adds widening improvements, and describes the combined
effect that pavement improvements and widening improvements would be expected
to have on the operational performance of rural Interstate highways. The third
and fourth analyses contain comparable material for urban Interstate highways.
The fifth and sixth analyses combine the earlier analyses, and examine
rural/urban tradeoffs. The seventh and eighth analyses project future rural and
urban bridge conditions. The ninth analysis combines the separate highway and
bridge analyses and serves as the starting point for the identification of the
resources required to maintain and improve the Interstate system, which is
discussed in the next section.
Each separate analysis includes a table and chart showing the potential
impacts of a range of different investment levels. Each table identifies the
effects of continuing to invest at 1997 levels in constant dollar terms over
the next 10 years, and the investment required to achieve certain performance
targets. Since highway capital spending is expected to grow in constant dollar
terms as TEA-21 is implemented, this section includes a simple forecast of
10-year funding levels, which is referenced in each of the analyses of future
conditions and performance.
The highway condition and performance forecasts utilize the Highway Economic
Requirements System (HERS), while the bridge analysis is based on the Bridge
Needs and Investment Process (BNIP). These models were generally utilized in
this analysis in the same manner as was used to develop the investment
requirements in Chapter 7. There are differences in the results however, since
Chapter 7 presents average annual values for a 20-year analysis, while this
study is based on a 10-year analysis. Note that all dollar values cited in this
section are stated in constant 1997 dollars.
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