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From page 127... ... 5 System Investment Needs: A 20-Year Horizon As the Interstate Highway System enters its seventh decade, the proposition that it can continue to serve the country effectively for many more years without extensive renewal and modernization is unsupportable. Much about the future is unforeseeable, particularly beyond the next two decades, given that, as discussed in the preceding chapter, advances in technology and changes in climate have the potential to affect the system in profound but still indeterminate ways. Read the entire page →
From page 128... ... 128 NATIONAL COMMITMENT TO THE INTERSTATE HIGHWAY SYSTEM modernizing the Interstate System under various, historically informed assumptions about plausible traffic growth. The average annual investment required for some of these elements can be approximated using available modeling systems, while that for other elements cannot be quantified as readily because of a lack of data, modeling capabilities, and other relevant information about the specific actions required to address them. Read the entire page →
From page 129... ... SYSTEM INVESTMENT NEEDS: A 20-YEAR HORIZON 129 Study of the Future 3R, 4R, and Capacity Needs of the Interstate System (Miller et al. Read the entire page →
From page 130... ... 130 NATIONAL COMMITMENT TO THE INTERSTATE HIGHWAY SYSTEM brief discussion of the improvements that will eventually be needed to add resilience to the system and modify its length and scope to accommodate a changing geography of user demand, a discussion that is necessarily limited because the committee could find no reasonable basis for estimating the cost of making these improvements over the next 20 years. Before considering the annual spending that will be needed for Interstate System renewal and modernization over the next two decades, the chapter considers spending on the system over the past two decades as context for the nature and scale of the investment that lies ahead. Read the entire page →
From page 131... ... SYSTEM INVESTMENT NEEDS: A 20-YEAR HORIZON 131 operations and control systems and safety and environmental enhancements (FHWA 2016b, Table SF-12A) Read the entire page →
From page 132... ... 132 NATIONAL COMMITMENT TO THE INTERSTATE HIGHWAY SYSTEM The most common pavement rehabilitation procedure is to replace the surface course through resurfacing, which is typically done with an asphalt overlay.1 In 2014, this spending category accounted for about two-thirds of state pavement-related expenditures, compared with previous highs of 57 percent in 2000 and 63 percent in 2010. Most of the increase in total pavement-related expenditures during the 17-year period, which have grown in real terms by 50 to 70 percent since the mid-2000s, stemmed from increases in spending on surface treatments. Read the entire page →
From page 133... ... SYSTEM INVESTMENT NEEDS: A 20-YEAR HORIZON 133 2011. Otherwise, however, annual bridge spending in real terms was stable throughout the decade preceding 2014. Read the entire page →
From page 134... ... 134 NATIONAL COMMITMENT TO THE INTERSTATE HIGHWAY SYSTEM Although the types of work required to reduce these backlogs have changed somewhat over time, the total has remained at about $150 billion. As will be discussed below, this figure does not fully account for the spending that will be needed to reconstruct aging and deteriorating pavement foundations, whose condition is not tracked by HPMS. Read the entire page →
From page 135... ... SYSTEM INVESTMENT NEEDS: A 20-YEAR HORIZON 135 improvements and calculate their impacts on aspects of system condition and performance. Box 5-1 lists the categories of benefits and costs monetized in HERS, as well as the measures that are used to calculate condition and performance. Read the entire page →
From page 136... ... 136 NATIONAL COMMITMENT TO THE INTERSTATE HIGHWAY SYSTEM Clearly such a limited set of monetized benefits and costs cannot account for all societal and economic impacts and their incidence, nor can the measures of system condition and performance include all criteria that may be of interest to highway users and policy makers. Furthermore, neither HERS nor NBIAS considers all types of potential highway and bridge improvements or the broader set of options at the disposal of policy makers for achieving a specific desired outcome. Read the entire page →
From page 137... ... SYSTEM INVESTMENT NEEDS: A 20-YEAR HORIZON 137 longer term, increased highway capacity may improve the accessibility of a region, stimulating economic and land development and thus encouraging the generation of new trips, or inducing demand. Conversely, as congestion increases when capacity becomes constrained and is not increased, some travelers may change their behavior to avoid the resultant delay, in which case the overall effect will be to suppress travel demand to a degree. Read the entire page →
From page 138... ... 138 NATIONAL COMMITMENT TO THE INTERSTATE HIGHWAY SYSTEM BOX 5-2 Applicability of Highway Economic Requirements System (HERS) and National Bridge Investment Analysis System (NBIAS) Read the entire page →
From page 139... ... SYSTEM INVESTMENT NEEDS: A 20-YEAR HORIZON 139 Assumed Future Rates of Growth in VMT To use HERS and NBIAS to make estimates of Interstate investment needs, it is necessary to specify future rates of VMT growth as inputs to the models. While the current state of the Interstate Highway System is a major determinant of future investment needs (as noted earlier in discussing the investment backlog) Read the entire page →
From page 140... ... 140 NATIONAL COMMITMENT TO THE INTERSTATE HIGHWAY SYSTEM for the next 20 years -- comparable to trends observed in recent decades and corresponding to the country's projected population gains, factoring in expected economic growth. This report uses a midrange or "nominal" VMT growth rate of 1.5 percent, with low and high excursions of 0.75 and 2.0 percent, respectively, which the committee believes to be reasonable lower and upper bounds (see Figure 5-4) Read the entire page →
From page 141... ... SYSTEM INVESTMENT NEEDS: A 20-YEAR HORIZON 141 demands on the system. For example, in HERS the benefits of a candidate improvement are measured in terms of the savings to users (lower travel times, improved safety, and reduced vehicle operating costs, such as fuel, tire, and vehicle depreciation costs) Read the entire page →
From page 142... ... 142 NATIONAL COMMITMENT TO THE INTERSTATE HIGHWAY SYSTEM FIGURE 5-5 Schematic of application of HERS and NBIAS models for calculating Interstate Highway System investment needs for the next 20 years. Interstate Highway Interstate Bridges Traffic Growth 3 levels: • Low VMT • Nominal VMT • High VMT HERS Benefit-cost ratio (BCR) Read the entire page →
From page 143... ... SYSTEM INVESTMENT NEEDS: A 20-YEAR HORIZON 143 ESTIMATING 20-YEAR PAVEMENT AND BRIDGE RENEWAL INVESTMENT NEEDS At a Glance • Applying a strategy that invests in all cost-beneficial improvements, pavement investment needs average on the order of $27– $32 billion annually over the next 20 years (roughly double the current spending levels) , based on assumed growth in VMT ranging from 0.75 to 2.0 percent per year. Read the entire page →
From page 144... ... 144 NATIONAL COMMITMENT TO THE INTERSTATE HIGHWAY SYSTEM As noted previously, a significant shortcoming of HERS for assessing pavement investment needs is that it does not consider all pavement conditions and types of improvements, partly because of limitations in the model's data source, HPMS. The condition of pavements is recorded in HPMS mainly according to a measure of ride quality, the International Roughness Index (IRI) Read the entire page →
From page 145... ... SYSTEM INVESTMENT NEEDS: A 20-YEAR HORIZON 145 will find it necessary to increase spending on reconstruction of Interstate pavements over the next decade and beyond because much of the system's original foundation will not have been rebuilt. The inability of HERS to estimate full-depth reconstruction needs is problematic for estimating longer-term pavement investment needs. Read the entire page →
From page 146... ... 146 NATIONAL COMMITMENT TO THE INTERSTATE HIGHWAY SYSTEM that the HERS results should be adjusted upward by a factor of 2. In the sections that follow, pavement investment needs are calculated first using HERS only, and second by applying the PHT-derived adjustment factor. Read the entire page →
From page 147... ... SYSTEM INVESTMENT NEEDS: A 20-YEAR HORIZON 147 However, the amount of mileage that has actually been impacted by these investments during highway reconstruction projects is not known. Whereas states are required to report to FHWA their total annual expenditures on Interstate reconstruction projects, they are not required to report the number of miles or lane-miles involved. Read the entire page →
From page 148... ... 148 NATIONAL COMMITMENT TO THE INTERSTATE HIGHWAY SYSTEM that the average investment is about $2.8 million per lane-mile on a rural Interstate and about $5 million per lane-mile on an urban Interstate (without adding any improvements beyond pavement reconstruction) Read the entire page →
From page 149... ... SYSTEM INVESTMENT NEEDS: A 20-YEAR HORIZON 149 uncoated reinforcing steel within the deck, causing corrosion that induced concrete surface spalling and potholes. Decks account for the majority of state spending on bridges, mainly for repair and rehabilitation necessitated by damage from the effects of corrosion and heavy traffic loadings (Azizinamini et al. Read the entire page →
From page 150... ... 150 NATIONAL COMMITMENT TO THE INTERSTATE HIGHWAY SYSTEM Two measures were used for bridge condition: (1) the percentage of total Interstate bridge deck surface area that would be rated as structurally deficient, and (2) Read the entire page →
From page 151... ... SYSTEM INVESTMENT NEEDS: A 20-YEAR HORIZON 151 tends to be a high priority for safety reasons and because of the high value and use of Interstate bridges. Somewhat higher annual investments (~25 percent) Read the entire page →
From page 152... ... 152 NATIONAL COMMITMENT TO THE INTERSTATE HIGHWAY SYSTEM Along with these substantial investments in pavement and bridge rehabilitation and reconstruction, additional investments will be required to expand and manage the Interstate Highway System's capacity to handle future traffic. For reasons noted earlier, investments that will be required to accommodate this traffic demand are much more difficult to project because they are highly dependent on assumptions about future travel demand and its relationship to capacity. Read the entire page →
From page 153... ... SYSTEM INVESTMENT NEEDS: A 20-YEAR HORIZON 153 period of 1.5 percent annual VMT growth) might be an acceptable investment. Read the entire page →
From page 154... ... 154 NATIONAL COMMITMENT TO THE INTERSTATE HIGHWAY SYSTEM Adding Operational Improvements Options for accommodating various traffic volumes that are amenable to analysis using HERS are ramp metering, incident management systems, hard shoulder running, managed lanes, variable speed limits, integrated corridor management, and weather management. Figure 5-6 shows how investing in a combination of these operational improvements affects delay under different conditions of annual VMT growth. Read the entire page →
From page 155... ... SYSTEM INVESTMENT NEEDS: A 20-YEAR HORIZON 155 corridors that are the locations of much of the country's traffic growth and suffer chronically high peak-period congestion. Tolling is increasingly being used to allocate scarce urban highway capacity and is typically implemented by adding toll-managed lanes, sometimes called express toll lanes. Read the entire page →
From page 156... ... 156 NATIONAL COMMITMENT TO THE INTERSTATE HIGHWAY SYSTEM congestion remains in the general-purpose lanes after the premium lane has been added. Truck-Only Lanes Data from a recent NCHRP report indicate that adding a truck-only lane costs about $6.7 million per mile (Cambridge Systematics, Inc. Read the entire page →
From page 157... ... SYSTEM INVESTMENT NEEDS: A 20-YEAR HORIZON 157 the cost estimates in Table 5-7 cannot be added to the numbers in the summary table in the following section. SUMMARY OF 20-YEAR INVESTMENT NEEDS Assuming Interstate traffic growth rates derived from forecasts of U.S. Read the entire page →
From page 158... ... 158 NATIONAL COMMITMENT TO THE INTERSTATE HIGHWAY SYSTEM TABLE 5-7 Estimated Spending Needs for Interstate Highway Renewal and Modernization Over the Next 20 Years (minimum benefit-cost ratio [BCR] Read the entire page →
From page 159... ... SYSTEM INVESTMENT NEEDS: A 20-YEAR HORIZON 159 Table 5-7 summarizes estimates derived from the models used herein, in some cases supplemented by additional sources of information. The table includes only improvements that confer positive net benefits (BCR ≥1) Read the entire page →
From page 160... ... 160 NATIONAL COMMITMENT TO THE INTERSTATE HIGHWAY SYSTEM FIGURE 5-7 Average investment (federal and state) per year to achieve specified peak-period delay levels in 20 years relative to 2016 (assuming 1.5 percent annual growth in vehicle-miles traveled [VMT] Read the entire page →
From page 161... ... SYSTEM INVESTMENT NEEDS: A 20-YEAR HORIZON 161 that the predicted totals are more likely to underestimate than overestimate actual investment needs. This judgment is based on the fact that, irrespective of the specific rates of growth in traffic over the next two decades, the existing system has a large backlog of work that will require substantial investment in itself. Read the entire page →
From page 162... ... 162 NATIONAL COMMITMENT TO THE INTERSTATE HIGHWAY SYSTEM While these criteria are intended to ensure connectivity and prevent duplication, they distinguish among investments that would serve the national interests, as opposed to serving mainly state or local interests. The criteria include grounds for replacement of Interstate highway segments (FHWA n.d.-c) Read the entire page →
From page 163... ... SYSTEM INVESTMENT NEEDS: A 20-YEAR HORIZON 163 route that was never completed. In its place, DDOT planned to convert the withdrawn Interstate segment to an urban boulevard. Read the entire page →
From page 164... ... 164 NATIONAL COMMITMENT TO THE INTERSTATE HIGHWAY SYSTEM with I-69 as discussed in Chapter 3) would be required to convert the highway to an Interstate. Read the entire page →
From page 165... ... SYSTEM INVESTMENT NEEDS: A 20-YEAR HORIZON 165 chapter were derived from modeled benefit-cost calculations -- the approach recommended by Congress in requesting this study. The following estimates are intended to provide general guidance regarding the magnitude of investments required over the next 20 years under a moderate investment strategy that encompasses all cost-beneficial improvements. Read the entire page →
From page 166... ... 166 NATIONAL COMMITMENT TO THE INTERSTATE HIGHWAY SYSTEM to require billions, perhaps many billions, in additional spending. These investments would be necessary to reconfigure and reconstruct many of the system's roughly 15,000 interchanges (Gehr 2010, 9) Read the entire page →
From page 168... ... 168 NATIONAL COMMITMENT TO THE INTERSTATE HIGHWAY SYSTEM Gehr, D Read the entire page →

From page 127...

... 5 System Investment Needs: A 20-Year Horizon As the Interstate Highway System enters its seventh decade, the proposition that it can continue to serve the country effectively for many more years without extensive renewal and modernization is unsupportable. Much about the future is unforeseeable, particularly beyond the next two decades, given that, as discussed in the preceding chapter, advances in technology and changes in climate have the potential to affect the system in profound but still indeterminate ways.