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Status of the Nation's Highways, Bridges, and Transit:
2002 Conditions and Performance Report

Chapter 3: System Conditions
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Index
Introduction
Highlights
Executive Summary
Part I: Description of Current System
Ch1: The Role of Highways and Transit
Ch2: System and Use Characteristics
Ch3: System Conditions
Ch4: Operational Performance
Ch5: Safety Performance
Ch6: Finance

Part II: Investment Performance Analyses
Ch7: Capital Investment Requirements
Ch8: Comparison of Spending and Investment Requirements
Ch9: Impacts of Investment
Ch10: Sensitivity Analysis

Part III: Bridges
Ch11: Federal Bridge Program Status of the Nation's Bridges

Part IV: Special Topics
Ch12: National Security
Ch13: Highway Transportation in Society
Ch14: The Importance of Public Transportation
Ch15: Macroeconomic Benefits of Highway Investment
Ch16: Pricing
Ch17: Transportation Asset Management
Ch18: Travel Model Improvement Program
Ch19: Air Quality
Ch20: Federal Safety Initiatives
Ch21: Operations Strategies
Ch22: Freight

Part V: Supplemental Analyses of System Components
Ch23: Interstate System
Ch24: National Highway System
Ch25: NHS Freight Connectors
Ch26: Highway-Rail Grade Crossings
Ch27: Transit Systems on Federal Lands

Appendices
Appendix A: Changes in Highway Investment Requirements Methodology
Appendix B: Bridge Investment/Performance Methodology
Appendix C: Transit Investment Condition and Investment Requirements Methodology
List of Contacts

Road Conditions

Pavement Terminology & Measurements

Pavement condition affects costs associated with travel, including vehicle operation, delay, and crash expenses. Poor road surfaces cause additional wear or even damage to vehicle suspensions, wheels, and tires. Delay occurs when vehicles slow for potholes or very rough pavement; in heavy traffic, such slowing can create significant queuing and subsequent delay. Unexpected changes in surface conditions can lead to crashes, and inadequate road surfaces may reduce road friction, which affects the stopping ability and maneuverability of vehicles.

The pavement condition ratings in this section are derived from one of two measures: International Roughness Index (IRI), and the Present Serviceability Rating (PSR). The IRI measures the cumulative deviation from a smooth surface in inches per mile. The PSR is a subjective rating system based on a scale of 1 to 5. Prior to 1993, all pavement conditions were evaluated using PSR values. Exhibit 3-2 contains a description of the PSR system.

    
Exhibit 3-2

Present Serviceability Rating (PSR)
 
PSR DESCRIPTION
4.0- 5.0
Only new (or nearly new) superior pavements are likely to be smooth enough and distress free (sufficiently free of cracks and patches) to qualify for this category. Most pavements constructed or resurfaced during the data year would normally be rated in this category.
3.0 - 4.0
Pavements in this category, although not quite as smooth as those described above, give a first-class ride and exhibit few, if any, visible signs of surface deterioration. Flexible pavements may be beginning to show evidence of rutting and fine random cracks. Rigid pavements may be beginning to show evidence of slight surface deterioration, such as minor cracking and spalls.
2.0 - 3.0
The riding qualities of pavements in this category are noticeably inferior to those of the new pavements and may be barely tolerable for high-speed traffic. Surface defects of flexible pavements may include rutting, map cracking, and extensive patching. Rigid pavements may have a few joint fractures, faulting and/or cracking and some pumping.
1.0 - 2.0
Pavements have deteriorated to such an extent that they affect the speed of free-flow traffic. Flexible pavement may have large potholes and deep cracks. Distress includes raveling, cracking, and rutting and occurs over 50 percent or more of the surface. Rigid pavement distress includes joint spalling, faulting, patching, cracking, and scaling and may include pumping and faulting.
0.0 - 1.0
Pavements are in extremely deteriorated conditions. The facility is passable only at reduced speed and considerable ride discomfort. Large potholes and deep cracks exist. Distress occurs over 75 percent or more of the surface.

States are required to report IRI data for the Interstate system, other principal arterials, rural minor arterials, and the National Highway System regardless of functional system. IRI reporting is recommended for all other functional classifications. The use of IRI data for reporting the status of rural major collectors and urban minor arterials has increased to 59 percent and 49 percent respectively of the miles for each. The total of urban collector miles reported using IRI data has risen to 34 percent. The procedure of reporting pavement condition status by IRI data for all functional classes is increasing.

The FHWA adopted the IRI for the higher functional classifications because this index uses a standardized procedure, is more consistent across jurisdictions, is an objective measurement, and is generally accepted as a worldwide pavement roughness measurement. The IRI system results in more consistent data for trend analyses and cross jurisdiction comparisons.

Q.
Do other measures of pavement condition exist?
A.
Other principal measures of pavement condition or distress such as rutting, cracking and faulting are not reported in HPMS. States vary in the inventories of these distress measures for their highway systems. To continue improving our pavement evaluation, FHWA has been working with AASHTO and States to establish standards for measuring roughness, cracking, rutting, and faulting.

Exhibit 3-3 contains a description of qualitative pavement condition terms and corresponding quantitative PSR and IRI values. The translation between PSR and IRI is not exact; IRI values are based on objective measurements of pavement roughness, while PSR is a subjective evaluation of a broader range of pavement characteristics. For example, a given Interstate pavement section could have an IRI rating of 165, but might be rated a 2.4 on the PSR scale. Such a section would be rated as acceptable based on its IRI, but would not have been rated as acceptable had PSR been used. Thus, the mileage of any given pavement condition category may differ depending on the rating methodology. The historic pavement data in this report only go back to 1993, when IRI data began to be collected. Caution should be used when making comparisons with older data from earlier editions of this report and when attempting to make comparisons between PSR and IRI data in general.

    
Exhibit 3-3

Pavement Condition Criteria (Old - New)
 
 
IRI RATING
PSR RATING
OLD CONDITION TERM CATEGORIES
INTERSTATE
OTHER
INTERSTATE
OTHER
Very Good
< 60
< 60
> 4.0
> 4.0
Good
60 to 94
60 to 94
3.5 to 3.9
3.5 to 3.9
Fair
95 to 119
95 to 170
3.1 to 3.4
2.6 to 3.4
Mediocre
120 to 170
171 to 220
2.6 to 3.0
2.1 to 2.5
Poor
> 170
> 220
< 2.5
< 2.0
 
All Functional Classifications
NEW RIDE QUALITY TERMS*
IRI RATING
PSR RATING
Good
< 95
> 3.5
Acceptable
< 170
> 2.5
* The threshold for "Acceptable" ride quality used in the 2002 Conditions and Performance Report is the 170 IRI value as set by the FHWA Performance Plan for the NHS. Some transportation agencies may use less stringent standards for lower functional classification highways to meet to be classified as "Acceptable".

The Federal Highway Administration 1998 National Strategic Plan introduced a new descriptive term for pavement condition: “acceptable ride quality.” That plan stated that by 2008, 93 percent of the National Highway System (NHS) mileage should meet pavement standards for “acceptable ride quality.” This goal was accomplished in 1999.

The FHWA has adopted a new metric based on the percent of vehicle miles traveled (VMT) on acceptable pavement. This metric of “Ride Quality” places more emphasis on the benefits of good pavements to the users instead of the physical condition of pavements. The FHWA Fiscal Year 2003 Performance Plan established the goal to have 92.5 percent of all VMT on the NHS to be on highways rated as acceptable or better ride quality by the year 2003. Exhibit 3-4 shows that in the year 2000, 91.0 percent of the VMT on the NHS were on pavements with acceptable ride quality. This is an increase of 0.4 percent over 1999. The NHS is discussed in more detail in Chapter 24.

    
Exhibit 3-4

Ride Quality on the National Highway System
 
 
1993
1995
1997
1999
2000
Total VMT on NHS
2,323,656,218
2,773,719,086
3,033,033,380
3,241,301,356
3,312,944,220
Total VMT on NHS Acceptable Pavements
2,091,128,773
2,468,245,187
2,703,120,410
2,937,157,991
3,013,967,870
Total Miles of NHS
142,837
154,204
157,582
158,971
158,802
Total Miles of NHS with Acceptable Ride Quality
127,872
139,408
144,643
147,817
148,538
Percent VMT on NHS Acceptable Pavements
90.0%
89.0%
89.1%
90.5%
90.9%
Percent Miles of NHS Pavement with Acceptable Ride Quality
89.5%
90.4%
91.8%
93.0%
93.5%
Source: Highway Performance Monitoring System.

Please note that the remainder of this chapter retains the traditional approach of describing pavement condition in terms of miles, rather than in terms of VMT.

To be rated acceptable, pavement performance must have an IRI value of less than or equal to 170 inches per mile. Good pavements comprise a subset of acceptable pavements. For a pavement to be rated as good, the IRI value must be less than or equal to 95 inches per mile. The Fiscal Year 2003 Performance Plan applies the same ride quality standard to all NHS routes, including those off the Interstate system. IRI is required to be reported for all NHS routes and is the preferred measure to determine acceptable ride quality.

In this chapter, overall ride quality is presented based on the qualitative condition terms good, acceptable, and not acceptable. The correlation between these condition terms to the condition terms used in previous C&P reports and to the IRI or PSR system is presented in Exhibit 3-3.

Overall Pavement Condition

The highway systems covered in this chapter include all mileage except rural minor collectors and local functional classifications. Based on the new metrics for ride quality, 86.0 percent of total road mileage evaluated was rated acceptable in 2000, including 43.5 percent that met the standard for good. [See Exhibit 3-5].

Acceptable Pavement
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Q.
Why isn’t a percentage shown for the “Good” category in 1993?
A.
In 1993, many States were in the process of converting from PSR to IRI reporting, and some anomalies in the overall data were observed. The percentage of pavement meeting the criteria to be classified as good was clearly inconsistent with that reported in subsequent years.

Rural and Urban Pavement Conditions

When discussing pavement conditions, it is important to note the different travel characteristics between rural and urban areas. As noted in Chapter 2, rural areas contain 78.2 percent of road miles, but only 39.4 percent of annual VMT. In other words, although rural areas have a larger percentage of road miles, the majority of travel is occurring in urban areas. According to 2000 data, pavement conditions in rural areas are slightly better than those in small urban and urbanized areas. 89.0 percent of total road miles in rural areas are rated acceptable while 79.8 percent of road miles in small urban areas are rated acceptable and 76.6 percent of the total road miles in urbanized areas are rated acceptable. The percentages shown as acceptable include mileage that also met the more stringent limit to be classified as good, 46.8 percent of rural miles, 37.5 percent of small urban miles, and 33.1 percent of urbanized miles. [See Exhibit 3-6]. Note that rural minor collectors and local functional system mileage are not included in these percentages.

Acceptable Pavement By Area
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Pavement conditions in rural areas have generally been improving over time. Since 1993, the percentage of road miles in acceptable condition has increased from 82.7 percent to 89.0 percent in rural areas. However, both small urban and urbanized areas have experienced decreases in acceptable pavement miles from 81.2 percent to 79.8 percent and from 82.4 percent to 76.6 percent, respectively, since 1993. Comparable trends can be observed in the percentage of miles rated as good. [See Exhibits 3-7, 3-8, & 3-9].

Acceptable Rural Area Pavement
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Acceptable Small Urban Area Pavement
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Acceptable Urbanized Area Pavement
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Pavement Condition by Functional Classification

As stated in Chapter 2, the functional classification for approximately 68.8 percent of total mileage is “local.” Nevertheless, roads classified as “Interstate” have the largest percentage of VMT, followed by other principal arterials, minor arterials, and major collectors. Therefore, ride quality on Interstate routes affects more users than ride quality on lower functional classifications. Interstate mileage in rural areas is 97.8 percent acceptable. In small urban areas, Interstate mileage is 95.6 percent acceptable. In urbanized areas, Interstate mileage is 93.0 percent acceptable.

For minor arterials, rural areas have a lower percentage of acceptable roads and a slightly higher percentage of miles of good roads than compared to urban areas. Urban areas also have a lower percentage of collector roads in acceptable condition and a lower percentage of collector roads miles in good condition when compared to rural areas.

A historical view helps clarify where pavement improvements are occurring and at what rate. Exhibit 3-14 shows the pavement condition by category, functional classification, and location from 1993 to 2000 based on the revised ride quality standards incorporated in this report. The exhibit illustrates that pavement conditions have changed in a variety of ways. For example, since 1993, the percentage of Interstate miles in rural areas classified as acceptable has increased from 93.5 percent to 97.8 percent.

The percentage of Interstate miles in urbanized areas rated as acceptable has increased from 89.8 percent to 93.0 percent. However, during the same time period, the percentage of Other Principal Arterials in urbanized areas listed as acceptable has decreased from 79.3 percent to 67.8 percent.

Combining the rural, small urban, and urbanized Interstate data illustrates that, overall, Interstate pavement performance has improved since 1993. The percentage of all Interstate mileage with “acceptable ride quality” increased from 92.6 percent in 1993 to 96.6 percent in 2000.

One consistent trend is the faster rate of pavement condition improvement in rural areas versus small urban and urbanized areas. Since 1993, the percent of total rural road miles classified as acceptable has increased in each of the four functional classes of rural roads. However, for the five functional classes of roads for small urban areas, two functional classifications—Interstate and Minor Arterials—have seen an increase in acceptable road miles, one functional class—Other Freeway and Expressway—has remained relatively stable, and two functional classes—Other Principal Arterials and Collectors—have experienced declines in acceptable road miles. For the five functional classes of roads for the urbanized areas, two functional classifications— Interstate and Other Freeway and Expressway— have seen an increase in acceptable road miles, and three functional classes have experienced declines in acceptable road miles—Other Principal Arterials, Minor Arterials, and Collectors. [See Exhibit 3-10].

    
Exhibit 3-10

Ride Quality by Functional System, For Selected Years 1993 - 2000
 
Percent Acceptable
FUNCTIONAL SYSTEM
1993
1995
1997
1999
2000
Rural Interstate
93.5%
94.5%
95.9%
97.6%
97.8%
Rural Principal Arterial
89.2%
91.4%
93.7%
95.5%
96.0%
Rural Minor Arterial
84.6%
85.1%
89.8%
92.0%
92.1%
Rural Major Collector
75.7%
82.5%
84.0%
79.7%
82.1%
Small Urban Interstate
93.5%
94.4%
95.8%
95.4%
95.8%
Small Urban Other Freeway & Expressway
93.7%
90.2%
91.2%
92.8%
93.7%
Small Urban Other Principal Arterial
85.8%
82.0%
80.5%
81.7%
82.9%
Small Urban Minor Arterial
77.7%
82.5%
82.2%
78.1%
80.0%
Small Urban Collector
74.0%
76.4%
75.9%
68.3%
68.9%
Urbanized Interstate
89.8%
90.0%
90.0%
92.2%
93.0%
Urbanized Other Freeway & Expressway
86.8%
87.6%
87.7%
88.8%
88.3%
Urbanized Other Principal Arterial
79.3%
75.9%
73.2%
67.6%
67.8%
Urbanized Minor Arterial
82.4%
82.1%
82.7%
78.5%
78.3%
Urbanized Collector
82.1%
84.4%
86.4%
80.3%
77.4%
Percent Good
FUNCTIONAL SYSTEM
1993
1995
1997
1999
2000
Rural Interstate
   
51.8%
56.9%
65.4%
68.5%
Rural Principal Arterial
  
41.3%
47.5%
54.0%
57.4%
Rural Minor Arterial
 
41.2%
45.5%
46.9%
47.8%
Rural Major Collector
 
48.8%
40.8%
33.2%
36.8%
Small Urban Interstate
 
49.8%
51.4%
58.2%
61.6%
Small Urban Other Freeway & Expressway
 
41.6%
35.8%
41.3%
43.8%
Small Urban Other Principal Arterial
 
36.8%
32.7%
33.7%
36.7%
Small Urban Minor Arterial
 
48.3%
46.5%
38.1%
38.9%
Small Urban Collector
 
44.3%
45.3%
30.3%
30.7%
Urbanized Interstate
 
41.4%
39.3%
45.0%
48.2%
Urbanized Other Freeway & Expressway
 
37.0%
31.4%
35.5%
38.0%
Urbanized Other Principal Arterial
 
29.3%
26.8%
23.7%
24.0%
Urbanized Minor Arterial
 
46.2%
46.0%
38.0%
38.4%
Urbanized Collector
 
45.5%
48.0%
31.5%
32.5%
Source: Highway Performance Monitoring System.

Roadway Alignment

Alignment adequacy affects the level of service and safety of the highway system. There are two types of alignment: horizontal and vertical. Inadequate alignment may result in speed reductions and impaired sight distance. In particular, trucks are affected by inadequate roadway alignment with regard to speed. Alignment adequacy is evaluated on a scale from Code 1 (best) to Code 4 (worst). Exhibit 3-11 explains the alignment rating system.

    
Exhibit 3-11

Alignment Rating
 
RATING
DESCRIPTION
Code 1
All curves and grades meet appropriate design standards.
Code 2
Some curves or grades are below design standards for new construction, but curves can be negotiated safely at prevailing speed limits. Truck speed is not substantially affected.
Code 3
Infrequent curves or grades occur that impair sight distance or severely affect truck speeds. May have reduced speed limits.
Code 4
Frequent grades occur that impair sight distance or severely affect truck speeds. Generally, curves are unsafe or uncomfortable at prevailing speed limit, or the speed limit is severely restricted due to the design speed limits of the curves.

Adequate alignment is more important on roads with higher travel speeds and/or higher volumes (e.g., Interstates). Alignment is normally not an issue in urban areas, therefore this section only presents rural data. Exhibits 3-12 and 3-13 illustrate that 95.6 percent of rural Interstate miles are classified as Code 1 for horizontal alignment and 92.8 percent are classified as Code 1 for vertical alignment. The share of rural roads classified as Code 4 for horizontal alignment is 7.7 percent, and 6.3 percent are rated Code 4 for vertical alignment. Roadway alignment continues to improve gradually as sections with poor alignment are reconstructed.

Rural Horizontal Alignment Adequacy
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Rural Vertical Alignment Adequacy
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Lane Width

Lane width affects capacity and safety; narrow lanes prevent a road from operating at capacity. As with roadway alignment, lane width is more crucial on functional classifications with the higher travel volumes.

Currently, high-type facilities (e.g. Interstates) are expected to have 12-foot lanes. Exhibits 3-14 and 3-15 illustrate that over 97 percent of Interstate miles meet the 12-foot standard. The percentage of miles with 12 foot-plus-lane widths is lower on lower-type facilities that carry less traffic. Lanes that are less than 9 feet wide are mainly concentrated on the collector roads.

Rural Lane Width by Functional System, 2000
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Small Urban and Urbanized Lane Width by Functional System, 2000
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Lanes have been widened over time through new construction, reconstruction, and widening projects. Since 1993, total rural mileage with lane width greater than or equal to 12 feet increased from 51.6 percent to 52.6 percent while the urban mileage with 12-foot-plus lanes decreased from 67.4 percent to 67.0 percent. Part of the urban decline may be attributable to the reclassification of roads from rural to urban as a result of population growth. [See Exhibit 3-16].

Miles of 12+ Foot Lane Width, 1993-2000
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Pavement Condition Based on Old Classification System

In previous C&P reports, the condition of pavement was listed by very good, good, fair, mediocre, and poor. In order to provide reference and a bridge between the rating system in previous reports and the new system, the overall pavement condition based on 2000 HPMS data is shown in Exhibit 3-17.

Percent Miles by Condition by Year
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Following the previous rating system, 15.5% of the miles are in very good condition and 28.0% are in good condition. Since 1997, the percentage of mileage in very good condition fell 1.0 percent while the percentage of mileage in good condition increased 1.0 percent. The percentage of fair pavement decreased from 42.4 percent to 41.2 percent while the percentage of mediocre pavement decreased slightly from 11.0 percent to 10.4 percent. Finally, the percentage of poor pavement decreased slightly from 5.1 percent to 4.9 percent since 1997.

Exhibits 3-18, 3-19, and 3-20 contain the portion of rural, small urban, and urbanized area pavement in the various condition categories, respectively, based on ride quality standards prior to the implementation of the revised standards.

Rural Areas Pavement Condition  by Functional Class, 2000
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Small Urban Areas Pavement Condition by Functional System, 2000
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Urbanized Areas Pavement Condition by Functional Class, 2000
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