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HPMS Reassessment 2010+

Final Report

Prepared by:

Office of Highway Policy Information
Federal Highway Administration

2.0 Background

2.1 Highway Performance Monitoring System (HPMS)

2.1.1 History of HPMS

The HPMS was developed in 1978 as a national highway transportation system database. In its current configuration, it includes limited data on all public roads, more detailed data for a sample of the arterial and collector functional systems, and area-wide summary information for urbanized, small urban, and rural areas. The HPMS replaced numerous uncoordinated annual state data reports as well as biennial special studies conducted by each state. These special studies had been conducted to support a 1965 Congressional requirement that a report on the Nation’s highway needs be submitted to Congress every two years. The first such Conditions and Performance Report was compiled in 1968. The first report to make use of the HPMS database was the 1980 Conditions and Performance Report, which was forwarded to Congress in January 1981.

Providing a snapshot of highway conditions was another reason for the original development of HPMS. In the 1970s, FHWA discovered that it had to respond to Congressional inquiries about the status of the Nation’s highways. HPMS provides a way to measure and track trends in highway characteristics, pavement conditions, and congestion at a national level.

The major purpose of the HPMS is to provide data that reflects the extent, condition, performance, use, and operating characteristics of the Nation’s highways. To meet this primary objective, the HPMS has gone through an evolutionary process that has recognized over time the changing needs for data related to these purposes.

2.1.2 Mission and Goals of HPMS

It is the mission of the Highway Performance Monitoring System (HPMS), as an integral part of the Nation’s suite of transportation databases, to provide a database and analysis process for assessing and reporting the extent, condition and performance of the Nation’s highway system in the most cost-effective manner consistent with the following goals:

  • Meet FHWA’s highway stewardship responsibilities, including preserving the national interest in the NHS;
  • Support Federal transportation policy analysis, planning, and performance measurement activities;
  • Provide data for Apportionment formulae;
  • Meet the various congressional requirements, including apportionment and the C&P report;
  • Provide a publicly accessible, consistently high-quality, objective, and timely national highway database;
  • Provide a database, analytical tools, and FHWA technical support that meets the needs of state, regional, and local agencies; and
  • Evolve to a data system which:
    • — Builds from the data systems of local, regional, and state governments;
    • — Is connected with a common geo-referencing system; and
    • — Avoids, whenever possible, collecting data which is not used by the collecting agency.

Appendix A contains a list of commonly used acronyms and abbreviations.

2.1.3 HPMS Description

The HPMS is a key national transportation data program that provides national-level highway inventory, condition, performance, and operating characteristics data to national, state, and regional customers. Examples of the type of data available through HPMS include pavement condition and travel by vehicle type.

There are three primary functions involved with HPMS: data collection, processing/reporting, and analyzing/applying. Although there is some overlap among functions, each function is primarily conducted by a different stakeholder group. Data collectors are state departments of transportation, metropolitan planning organizations, and local governments such as counties and cities. The processing and reporting of HPMS occurs within the FHWA Office of Highway Policy Information. Finally, users consist of a wide variety of customers, including U.S. DOT Federal Program Offices, other Federal agencies, U.S. Congress, states, MPOs, counties, and cities.

HPMS is used at the federal level for apportionment, performance measures, highway statistics and conditions reporting, and analytical models; it is one of the primary databases used by FHWA for conducting national-level surface transportation planning and policy studies. It is also used by a variety of state and local transportation agencies as well as other transportation interests. Some of these uses are extremely important for highway financing. For example, the biennial Conditions and Performance Report (C&P) to Congress documents future highway funding needs and HPMS-derived vehicle-miles traveled (VMT) estimates are used in the annual apportionment of Federal Aid highway funds to the states.

VMT estimation is probably the most ubiquitous use of HPMS — VMT is calculated and used at the national, state, and local levels. This is not surprising since the original primary intent of HPMS, when it was conceived in the late 1970s, was to provide a consistent basis for VMT estimation nationally. This is reflected in the sampling frame and the strong linkage to the Traffic Monitoring Guide for supplying traffic counts to HPMS.

The data also are used for assessing highway system performance under FHWA’s strategic planning process. Pavement condition data, congestion-related data, and traffic data are used extensively by the Administration to measure FHWA’s and the State’s progress in meeting the objectives embodied in the Vital Few, FHWA’s Performance Plan, and other strategic goals.

Over time, many applications have been developed that use HPMS as their source of data. These applications further demonstrate the utility of HPMS and have also put increasing demands on it. For example, the HERS model has become FHWA’s tool for developing the highly visible C&P Report and the Freight Analysis Framework (FAF) is used extensively for estimating current and future freight movement at the national-level such as in the Freight Facts and Figures series.

In addition, the HPMS serves needs of the states, MPOs and local government, and other customers in assessing highway condition, performance, air quality trends, and future investment requirements. Some states rely on traffic and travel data from the HPMS to conduct air quality analyses and make assessments related to determining air quality conformity. Others are using the same analysis models used by FHWA to assess their own highway investment needs using HERS—ST, which is the state version of the HERS model used by FHWA. As a result of these uses, states have an additional stake in assuring the completeness and quality of these data.

Finally, these data are the source of a large portion of information included in FHWA’s annual Highway Statistics and other media and publications. They are widely used in both the national and international arenas by other governments, transportation professionals, and industry professionals to make decisions that impact national and local transportation systems and our transportation dependent economy.

Table 2.1 summarizes the uses and users of HPMS.

Table 2.1.3 Users and Uses of HPMS Data
User Group Type of Application Description
FHWA Forecasted highway investment needs and performance (user costs and impacts) HPMS is the data source for the HERS model, which produces the information for the Biennial Conditions and Performance Report to Congress.
Annual reporting of highway conditions HPMS is the basis for much of the information produced in Highway Statistics, which includes trends in highway conditions, performance, and usage.
Freight planning HPMS data and the National Highway Planning Network are used by the Freight Analysis Framework for calibrating base year assignments and forecasting future freight flows.
Special policy and planning studies HPMS data are used in a variety of national studies every year. An example is 2004’s Traffic Congestion and Reliability Report.
Travel monitoring HPMS is the official source of VMT estimates, which are used throughout FHWA and U.S. DOT. VMT from HPMS is a factor for allocating highway funds to the states.
Public Road Mileage HPMS data is the official source of roadway mileage by jurisdiction.
State DOTs Forecasted highway investment needs and performance (user costs and impacts) State-HERS is used by many states for investment planning.
Metropolitan Planning Organizations Air quality conformity and planning HPMS is used for local VMT estimation.
Texas Transportation Institute National congestion monitoring HPMS Universe data is the basis for the annual Urban Mobility Study.
Transportation Research and Interest Groups Planning and policy analysis HPMS is used by many transportation professionals to produce various reports, including AASHTO’s “Bottom-line” reports, the Transportation Research Board’s policy studies, and the American Highway Users Alliance bottleneck studies.

The FHWA OHPI is not involved directly in data collection but relies on State DOTs for HPMS Data. OHPI performs data quality checks, and provides technical support and software to ease reporting requirements. The fact that FHWA relies on other agencies to provide data is highly significant since FHWA must balance the needs of its users (internal and external) with the capabilities of its providers to provide data at a reasonable level of effort. The difference in views between data needs and collection capabilities is the crux of the issue addressed during the Reassessment. A large number of data issues were considered and explored, and the organization and prioritization of the issues from a user and provider standpoint are key elements of the Reassessment.

Several reference documents describing HPMS are located on the FHWA HPMS web site (http://www.fhwa.dot.gov/policy/ohpi/hpms/index.cfm).

They include:

  • HPMS Field Manual, May 2005, Office of Highway Policy Information, Federal Highway Administration; and
  • HPMS Primer — Overview of the HPMS for FHWA, September 2006, Office of Highway Policy Information, Federal Highway Administration.

There is generally a lag between data collection in the field and the data showing up in a report. The following table indicates the timing of data collection and reporting.

Table 2.1.3 HPMS Timeline

Timeline (Click for Detailed Description)

2.2 Reassessment

2.2.1 Background of HPMS Reassessments

The HPMS has been modified several times since its inception. Changes in coverage and detail have been made since 1978 to reflect changes in highway systems; legislation and national priorities; to reflect new technology; and to consolidate or streamline reporting requirements.

Recognizing that needs and capabilities change over time, FHWA initiated a periodic review process for HPMS many years ago (“Reassessment”). The Reassessment process considers what changes should be made to HPMS data elements and collection procedures, including:

  • Should existing data elements be eliminated because they are not needed for most applications or because they are too onerous a burden on data collectors?
  • Are new data elements needed to support current and emerging applications? If so, can they be prioritized or limited to certain functional systems?
  • Should data elements be redefined (e.g., valid values) to match applications’ needs?
  • Should data be collected in a different manner (e.g., the factoring and reporting of traffic counts)?
  • What changes in the sampling schema should be made? Are the minimum VMT-based sample sizes adequate for providing system-level estimates of other highway conditions?

The last Reassessment was completed in 1999 and utilized a comprehensive stakeholder outreach process. In 1999, there was some question as to the need for HPMS, whereas this Reassessment is being performed in an environment where HPMS is recognized as an important program that needs some modifications to accommodate changing technological and application needs.

2.2.2 Purpose of this Reassessment

The purpose of this Reassessment is to review the HPMS in light of contemporary issues and anticipated future needs. The reauthorization of the Federal-aid highway program, as contained in SAFETEA—LU, provided an appropriate opportunity for the FHWA to undertake a Reassessment of the HPMS. Other reasons to reexamine the HPMS are further advancements in technology, changes to state data requirements, increased use of performance measures, and changes in the various uses of HPMS data by government, academia, and the private sector.

The vision for this Reassessment is for HPMS to meet the transportation community’s data needs in 2010 and beyond.

The mission is to respond to current and future business needs, address new data needs in SAFETEA—LU, capitalize on changing technology and, where possible, address resource constraints and institutional changes.

The objectives are to:

  • Meet new Federal needs including but not limited to: Policy, Safety, Operations, and Infrastructure;
  • Explore potential changes to HPMS to be more useful for most states and MPOs;
  • Capitalize on changing technology to enhance quality, efficiency, and data integration; and
  • Ensure data items meet all required needs (definitions/standardization/change, new items, delete items.)

The process for this Reassessment was carefully planned and implemented to ensure consistency with the process used for the last Reassessment. It also was designed to address policy/institutional (state and national) issues, data collection, data analysis tools/applications, emerging issues (such as safety), and all other issues related to HPMS users and collectors.

The first phase of the Reassessment was to identify what needed to be changed in coordination with Federal agencies. The second phase was to work with stakeholders to identify how the needs can be met and balanced with collection requirements. The third phase is the implementation of the identified needs within the context of the new data model.

2.2.3 How HPMS Addresses National Transportation Data Needs

The Federal need for transportation data transcends functional classification, ownership, and jurisdiction. While functional class, ownership, and jurisdiction are important categories, for which HPMS data are often summarized, they do not define the limits of FHWA’s needs for these data. Each issue area explored in this reassessment has had to consider the differing Federal and state data needs, while weighing these needs against the states’ ability (or willingness) to provide these data.

The ability to provide data, especially on roads not owned by the states (off-system), was often cited as being an area of concern. This was neither a surprise nor a new topic in the Reassessment; this has been a concern of the states since the inception of HPMS in 1978. However, to get a complete picture of the highway system in each state it has always been necessary for FHWA to have data on off-system roads.

The existing HPMS structure attempts to balance the need for off-system data with the States ability to provide these data, by dividing the HPMS data into three levels. Sample data are the most detailed, with each sample section being comprised of up to 98 data items. In the 2006 HPMS data, there are approximately 120,000 sample sections, with a total length of 137,000 miles. These sections represent approximately 980,000 miles of roads functionally classified from Interstate through (Major) Collector.

The next level is the universe data. Universe sections can contain a maximum of 46 data items on NHS sections, to a minimum of 28 data items on local roads. It should be noted that currently, most of the data on local roads are identification, system, jurisdictional, or ITS in nature. The “section length” data item is the only apportionment item (from these data) for local roads. Nationwide, there are approximately 1.13 million universe sections that represent all 4.012 million miles of public roads (2006 HPMS).

The final HPMS data level is the summary data. These data provide travel data for all functional systems, as well as the distribution of travel by six vehicle classes for all functional systems. Additional summary data are collected by urban/urbanized area, and for air quality non-attainment and maintenance areas.

These data are used individually or in combination to satisfy the various Federal data needs. The apportionment of Highway Trust Funds relies on all three data levels. Performance measures can use either the sample data alone or in combination with the universe data. Much of the HERS analysis for the C&P Report utilizes just sample data.

Key to the multilevel structure of HPMS is the national uses of these data; the quality of data; and the types of analyses performed using these data. The multilevel approach also helps compensate for variability between state transportation data collection efforts. States typically focus their data collection efforts on roads owned and maintained by the state. The following is from the 2006 HPMS data and illustrates the variability in state owned highway systems nationwide:

  • The degree of state ownership ranges from a low of 6.0 percent of the mileage carrying 41.8 percent of the VMT to a high of 92.8 percent of mileage carrying 93.4 percent of VMT. The national averages are 19.4 percent of mileage and 64.2 percent of VMT.
  • State ownership by Federal-aid highways is 90.4 percent for Interstate, 95 percent for other NHS and 49.3 percent for other Federal-aid highways.
  • While states generally have responsibility for higher functionally classified highways, 159,574 miles of state highways are functionally classified as Local highways and 80,999 miles are urban Collectors and rural Minor Collectors.

It is important to note that increasingly states are relying on other governmental agencies to provide HPMS data on off-state system roads. Cities, counties, and MPOs frequently provide HPMS data to the states, which then combine it with state-collected data before submitting it to FHWA. Ideally, FHWA would like all data to be of equally high quality, but it realizes that this is not always possible across all functional systems. FHWA continues to support the utilization of locally collected data in states’ HPMS submittals.

States generally follow the guidance and criteria, such as for functional class, but each state is different because of internal state and non-state highway organizations, highway system definitions, and operating procedures and regulations. To better accommodate these differences, FHWA is proposing several improvements to HPMS that will increase the ability of states to more efficiently provide quality, timely, and complete HPMS data. These improvements discussed in this report include:

  • New data model;
  • Metadata for pavements and traffic;
  • Coordination with safety, bridge, finance, and other databases;
  • Boundaries and functional classification.

Sample size and national/state system sampling schema are two areas that could be improved to address this issue, but due to budget and time limitations are being retained as long-term research projects for implementation in the mid to long term; beyond year 2010.

2.3 Uses of HPMS Data

2.3.1 Needs Assessment

The methods and assumptions used to analyze future highway, bridge, and transit investment scenarios are continuously evolving. Since the beginning of the highway report series in 1968, innovations in analytical methods, new empirical evidence, and changes in transportation planning objectives have combined to encourage the development and application of improved data and analytical techniques. Estimates of future highway investment requirements, as reported in the 1968 National Highway Needs Report to Congress, began as a combined “wish list” of State highway “needs.” As the focus of national highway investment changed from system expansion to management of the existing system during the 1970s, national engineering standards were defined and applied to identify system deficiencies, and the investments necessary to remedy these deficiencies were estimated. By the end of the decade, a comprehensive database, the Highway Performance Monitoring System (HPMS), had been developed to monitor highway system conditions and performance nationwide.
By the early 1980s, a sophisticated simulation model, the HPMS Analytical Process (AP), was available to evaluate the impact of alternative investment strategies on system conditions and performance. The procedures used in the HPMS-AP were founded on engineering principles. Engineering standards were applied to determine which system attributes were considered deficient, and improvement option “packages” were developed using standard engineering practice to potentially correct given deficiencies, but without consideration of comparative economic benefits and costs.

In 1988, the FHWA embarked on a long-term research and development effort to produce an alternative simulation procedure combining engineering principles with economic analysis, culminating with the development of the HERS model. HERS was first utilized to develop one of the two highway investment scenarios presented in the 1995 C&P report. In subsequent reports, HERS has been used to develop all of the highway investment scenarios.

The HERS model initiates the investment analysis by evaluating the current state of the highway system using information on pavements, geometry, traffic volumes, vehicle mix, and other characteristics from the Highway Performance Monitoring System (HPMS) sample dataset. Using section-specific traffic growth projections, HERS forecasts future conditions and performance across several funding periods. As used in this report, the future analysis covers four consecutive 5-year periods. At the end of each period, the model checks for deficiencies in eight highway section characteristics: pavement condition, surface type, volume/service flow (V/SF) ratio, lane width, right shoulder width, shoulder type, horizontal alignment (curves), and vertical alignment (grades).

Once HERS determines a section's pavement or capacity is deficient, it will identify potential improvements to correct some or all of the section's deficient characteristics. The HERS model evaluates seven kinds of improvements: resurfacing, resurfacing with shoulder improvements, resurfacing with widened lanes (aka minor widening), resurfacing with added lanes (aka major widening), reconstruction, reconstruction with widened lanes, and reconstruction with added lanes. For improvements that add travel lanes, HERS further distinguishes between those that can be made at “normal cost” and those on sections with limited widening feasibility that could only be made at “high cost.” HERS may also evaluate alignment improvements to improve curves, grades, or both.

When evaluating which potential improvement, if any, should be implemented on a particular highway section, HERS employs incremental benefit-cost analysis. The HERS model defines benefits as reductions in direct highway user costs, agency costs, and societal costs. Highway user benefits are defined as reductions in travel time costs, crash costs, and vehicle operating costs. Agency benefits include reduced maintenance costs (plus the residual value of projects with longer expected service lives than the alternative). Societal benefits include reduced vehicle emissions. Increases in any of these costs resulting from a highway improvement (such as higher emissions rates at high speeds or the increased delay associated with a work zone) would be factored into the analysis as a “disbenefit.”

These benefits are divided by the costs of implementing the improvement to arrive at a benefit-cost ratio (BCR) that is used to rank potential projects on different sections. The HERS model implements improvements with the highest BCR first. Thus, as each additional project is implemented, the marginal BCR and the average BCR of all projects implemented decline. However, until the point where the marginal BCR falls below 1.0 (i.e., costs exceed benefits), total net benefits will continue to increase as additional projects are implemented. Investment beyond this point would not be economically justified, since it would result in a decline in total net benefits.

Additional information on the HERS model can be found in the HERS Technical Report. The latest published version dated December 2000, is based on HERS version 3.26, which was utilized in the development of the 1999 edition of the C&P Report. The Technical Report for the State version of HERS was published in 2002 and can be found at: http://isddc.dot.gov/OLPFiles/FHWA/010945.pdf.

2.3.2 Performance Measures

HPMS data are used for a number of performance measures in FHWA, the National Highway Transportation Safety Administration (NHTSA), and the Federal Motor Carrier Safety Administration (FMCSA). For most of the performance measures, HPMS data are combined with other data, but there are some that rely solely upon HPMS. While data on the use and extent of the nation’s highway system are commonly cited in FHWA documents and in the media, they are not typically considered performance measures. The term refers to measures or goals established by the U.S. Department of Transportation or one of the individual agencies such as FHWA or NHTSA. The following is a brief description of some of the more commonly referenced performance measures and the HPMS data used.

2.3.2.1 Fatality Rates — Safety

The FHWA Office of Safety and NHTSA use VMT data derived from HPMS as the denominator in calculating fatality rates. This is done by dividing the total number of fatalities by the total VMT. VMT is determined for each section in HPMS by multiplying the AADT by the length of the section. The VMT are then summed for the various systems for which a fatality rate is desired; typically by State, functional class, and vehicle type. HPMS universe, sample, and summary data are all utilized for this analysis.

2.3.2.2 Pavement Smoothness — Mobility and Productivity

The FHWA Office of Pavement Technology reports the pavement smoothness performance measure, which is the percent of VMT on the NHS with pavement smoothness (IRI) of 95 inches/mile or better. HPMS universe data are used for this analysis, which involves determining 1) which sections on the NHS have an IRI of 95 in/mi or better, 2) calculating the VMT for each section, and 3) summing of VMT for these sections.

2.3.2.3 Congestion — Mobility and Productivity

The Office of Operations is responsible for the congestion performance measure, which is the percent of travel that occurs under congested conditions and is determined by the Texas Transportation Institute (TTI) and reported in their annual Urban Mobility Report. TTI uses HPMS sample data for approximately 403 urbanized areas within the United States on the freeways and arterial streets. Addition information on the Urban Mobility Report can be found on the TTI web site at: http://mobility.tamu.edu.

2.3.2.4 Special Analyses

HPMS data are routinely used for special analysis of highway system extent, condition, performance, and use. Some of these are recurring such as the analysis done for the Highway Cost Allocation Study or the Freight Analysis Framework. Of the non-recurring, some are very complex, but most are rather simple. The Strategic Multimodal Analysis (SMA) is an example of more complex analysis to use HPMS sample data, which builds off of the HERS analysis. Most, however, are along the lines of estimating the extent of access controlled Principal Arterials, or summing highway mileage by special traffic volume or pavement condition groups. The FAF uses HPMS passenger traffic data in assembling the freight corridors and determining freight movement performance.

2.3.2.5 Reports

HPMS data are cited in numerous DOT and FHWA publications. Some, such as Highway Statistics and the Conditions and Performance Report, which are produced by the Office of Policy and Governmental Affairs, have entire chapters dealing with HPMS data. The Bureau of Transportation Statistic’s Pocket Guide to Transportation is an example of a DOT report that summarized some of the HPMS data for multiple years. Most reports cite key statistics, such as the miles, lane-miles, or VMT for all public roads, or a portion as in the case of the Interstate System or National Highway System.

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