Office of Highway Policy Information
Federal Highway Administration
This appendix contains definitions to be used in preparing HPMS data for FHWA. Specific details addressing summary, universe, and sample data, and LRS (linear referencing system) data are later in this document and in the forthcoming HPMS Field Manual. This chapter along with the subsequent chapters provides necessary definitions, guidelines, coding instructions, reporting formats, and update specifications necessary to facilitate the reporting of current, consistent, and uniform data on a nationwide basis.
Aggregation Business Rule: It describes how the HPMS database and software will aggregate data as the sample view is created. Typically rules include: weighted average, predominance, proportional, or sum.
Certification of Public Road Mileage: An annual document furnished by each state to FHWA certifying the total public road length in the State as of December 31st. This document is to be signed by the Governor of the State or by his/her designee and provided to FHWA by June 1st of the year following (23 CFR 460). See the definition of ”Public Road“.
Collection Cycle: The period for which the data are collected; typically annually or every 2- or 3-years.
Collection Requirements: Description of data collection requirements to ensure consistency. For example, for IRI, we will be requiring States to include bridges. This goes beyond a reporting requirement in that we expect every State to follow these procedures when collecting the data.
Combination Truck: Any multi-unit vehicle described by vehicle types 8-13.
Comment File: A text file that accompanies the HPMS data submittal to FHWA. It explains data issues, problems, deficiencies, unusual conditions, and any significant changes from the previous HPMS submittal. It should be provided as an electronic file attached to the HPMS submittal.
Confidence Level/Precision Level: The degree of accuracy resulting from the use of a statistical sample. For example, if a sample is designed at the 90-10 confidence (precision) level, the resultant sample estimate will be within ±10 percent of the true value, 90 percent of the time.
(Data) Description: Short description of the data and where used. The bulk of the HPMS Field Manual work will revolve around expanding on this text.
D-Factor: The proportion of traffic moving in the peak direction of travel during peak hours is denoted as D-factor. The D-factor is an important factor in highway capacity analysis, especially for two-lane rural highways.
Divided Highway: A multi-lane facility with a curbed or positive barrier median or a median that is at least 1.2 meters (4 feet) or wider.
Valid values: Describes the actual data to be coded; includes the range of expected values and possible codes.
English Units: The term “English“ refers to the United States legislative interpretation of the units as defined in a document prepared by the National Institute of Standards and Technology (NIST), U.S. Department of Commerce, Special Publication 330. Commonly used English units in HPMS are miles, feet, and inches.
Expressway: A divided highway facility with partial control of access and two-or-more lanes for the exclusive use of through traffic in each direction; includes grade separations at most major intersections.
Extent: Where the data are required: functional system, NHS, Sample, paved etc.
Federal-Aid Highways: All NHS routes and other roads functionally classified as Interstate, Other Freeways & Expressways, Other Principal Arterials, Minor Arterials, Major Collectors, and Urban Minor Collectors.
FHWA-Approved Adjusted Census Urban Boundary: Designated boundaries of a Census urban place or urbanized area as adjusted by responsible State and local officials in cooperation with each other, subject to the approval by FHWA (23 U.S.C. 101). Urban and rural data in HPMS must be reported in accordance with FHWA-approved adjusted boundaries.
Freeway: A divided highway facility with full control of access and two or more lanes for the exclusive use of through traffic in each direction.
Functional Systems: Functional systems result from the grouping of highways by the character of service they provide. The functional systems designated by the States in accordance with 23 CFR 470 are used in the HPMS. Guidance criteria and procedures are provided in the FHWA publication Highway Functional Classification: Concepts, Criteria, and Procedures, March 1989, as amended. In addition, interim guidance has been issued by FHWA, spring 2008.
Geographic Information System (GIS): A system for the management, display, and analysis of spatial information.
Geospatial Data: The HPMS geospatial data provide a linear referencing system for the universe and sample data on selected highway functional systems. The represented functional systems include Interstate, Other Freeways & Expressways, Other Principal Arterials, Minor Arterials, Major Collectors, Urban Minor Collectors, and all National Highway System (NHS) routes and connectors. This permits the analyses of HPMS data in a GIS environment.
Highway: The term highway includes roads, streets, and parkways and all their appurtenances (23 U.S.C. 101).
K-Factor: The proportion of annual average daily traffic occurring in the analysis period. For rural highways, the proportion has often been assumed to occur at the 30th highest hour, which is often used as the basis for estimates of design-hour volume. For urban roadways, a design hour for the repetitive weekday peak periods is common.
Linear Referencing System (LRS): A set of procedures for determining and retaining a record of specific points along a highway. Typical methods used are kilometerpoint (milepoint), kilometerpost (milepost), reference point, and link-node.
LRS Data: Provides a linear referencing system for the universe and sample data on selected highway functional systems.
Maintenance Area: Any geographic region of the Unites States previously designated non-attainment pursuant to the CAA Amendments of 1990 and subsequently redesigns Ted to attainment subject to the requirement to develop a maintenance plan under Section 175A of the CAA, as amended. HPMS data are used for travel tracking for air quality assurance purposes in non-attainment and maintenance areas as required by EPA under the 1990 CAAA (Section 187) and the Transportation Conformity Rule, 40 CFR parts 51 and 93. More specifically, these data are used primarily for establishing regional transportation-related emissions for transportation conformity purposes. Estimated travel based on these data is used for calibration and validation of base-year network travel models when required for non-attainment or maintenance areas.
Metadata: Describes how data are collected or converted for reporting; explains variations in data that do not warrant the establishment of a collection requirement e.g. type of equipment used, sampling frequency etc.
Metric Units: The term “metric“ refers to the modernized metric system known as the International System (SI). Further information is available under Nest’s Special Publication 811, titled Guide for the Use of the International System of Units: the Modernized Metric System and the American Society for Testing and Materials (ASTM) Standard E380-89a. Commonly used metric units in the HPMS are kilometers, meters, and millimeters.
Metropolitan Planning Organization (MPO): The term MPO is used in HPMS as defined in 23 U.S.C. 134.
National Ambient Air Quality Standards (NAAQS) Non-attainment Area: Any geographic region of the United States which has been designated under Section 107 of the Clean Air Act for any pollutant for which a national ambient air quality standard exists. HPMS data are used for travel tracking for air quality assurance purposes in non-attainment and maintenance areas as required by EPA under the 1990 CAAA (Section 187) and the Transportation Conformity Rule, 40 CFR parts 51 and 93. More specifically, these data are used primarily for establishing regional transportation-related emissions for transportation conformity purposes. Estimated travel based on these data is used for calibration and validation of base-year network travel models when required for non-attainment or maintenance areas.
National Highway System (NHS): The National Highway System is a network of nationally significant highways approved by Congress in the National Highway System Designation Act of 1995. It includes the Interstate System and over 116,000 miles of other roads and connectors to major intermodal terminals. All NHS routes and connectors must be identified in the HPMS.
National Network: These are the routes designated for use by dimensioned commercial vehicles under the Surface Transportation Assistance Act (STAA) of 1982 as identified in 23 CFR 658, Appendix A. Nationally designated truck routes include the Interstate System (a few sections are exempted by Federal law in Minnesota, Virginia, and District of Columbia); non-Interstate routes specifically listed in 23 CFR, Appendix A, as amended, and the other non-Interstate existing Federal-Aid Primary (FAP) routes as defined prior to June 1, 1991, that STAA-dimensioned commercial vehicles may legally operate on.
Some States have allowed STAA-dimensioned commercial vehicles to operate on other State routes. These and other non-national truck network roads used between the STAA national network and terminals and facilities for food, fuel, repairs, and rest under the reasonable access rule are not nationally designated truck routes. These routes are not to be included.
PK: Primary Key — It indicates the data fields used for linking data in a table with data in other tables.
Public Road: A public road is any road or street owned and maintained by a public authority and open to public travel. [23 U.S.C. 101(a)] Under this definition, a ferryboat route is not a public road.
Roadway: The portion of a highway intended for vehicular use.
Rural Areas: All areas of a State outside of the FHWA-approved adjusted Census boundaries of small urban and urbanized areas.
Single-Unit Truck: Any single-unit vehicle described by vehicle types 4-7.
Small Urban Areas: Small urban areas are defined by Census as places of 5,000 to 49,999 urban populations (except in the case of cities in Maine and New Hampshire) outside of urbanized areas. As a minimum, a small urban area includes any place containing an urban population of at least 5,000 as designated by Census. Designated boundaries of an urban place (or urban cluster) can be adjusted by responsible State officials subject to approval by FHWA (23 U.S.C. 101). Urban and rural data in HPMS must be reported in accordance with FHWA-approved adjusted boundaries. Area revisions as needed are expected to be submitted especially shortly after the latest Decennial (or special) Census information becomes available.
Sample Data: These data consist of additional inventory, condition, use, pavement, operational, and improvement data that complement the universe data for those sections of roadway that have been selected as samples. When expanded through use of an appropriate expansion factor, the data represents the entire universe from which the sample was drawn, permitting evaluation of highway system performance. The sample sections form nominally “fixed” panels of road segments that are monitored on an established cyclical basis. Samples can be added or deleted from the sample panels as the need arises.
Panels of roadway sections are established using a statistically designed sampling plan based on the random selection of road segments at predetermined precision levels. The sample is stratified by area, by functional system, and by traffic volume group. Sample selection is done randomly within each stratum (a predetermined AADT volume group) for each arterial and major collector functional highway system in rural, and for each arterial and collector functional system in small urban and urbanized areas of the State.
Each urbanized area needs to be sampled individually. Rural and small urban areas (populations of 5,000 to 49,999) are sampled collectively statewide.
Sample Sections: Sections selected at random from the universe of arterial and collector systems (excluding rural minor collector) for which additional physical and operational data elements are reported along with the universe data.
State (Codes): The term “State” refers to any one of the 50 States, the District of Columbia, or the Commonwealth of Puerto Rico. The Federal Information Processing Standard Codes for States (FIPS PUB 5-2) are included in Appendix A.
Strategic Highway Network (STRAHNET): The STRAHNET includes
highways which are important to the United States strategic defense policy
and which provide defense access, continuity, and emergency capabilities
for the movement of personnel, materials, and equipment in both peacetime
and war time.
Structures: A structure including supports erected over a depression or an obstruction, such as water, highway, or railway, and having a track or passageway for carrying traffic or other moving loads, and having an opening measured along the center of the roadway of more than 20 feet (6.1 meters) between under copings of abutments or spring lines of arches, or extreme ends of openings for multiple boxes; it may also include multiple pipes, where the clear distance between openings is less than half of the smaller contiguous opening. Structures can include tunnels.
Summary Data: These data consist of annual summary reports for certain data not included in the HPMS universe and sample data set for the rural minor collector and local functional systems. Summary data must be coded manually onto the several summary screens contained in the HPMS submittal software. These additional data are derived from State and local sources such as statewide highway databases, management systems, Intelligent Transportation Systems (ITS) and traffic monitoring systems, and data made available from local governments and MPOs.
System Length: The total length of public roads as of December 31st of a data year that is to be reported via HPMS (see definition of public road). System length includes all public roads owned by Federal, State, and local governments, or instrumentality thereof, within the boundaries of the reporting State. Planned, un-built facilities on the NHS are also reported in the HPMS system length.
UK : Unique Key — It is used to uniquely identify each section record in the table. There can be one and only one row with each unique key value.
Universe Data: Data representing total system length including National Highway System length not yet built or open to traffic. These data consist of a complete inventory of length (kilometers or miles) by functional system, jurisdiction, geographic location, (rural, small urban and urbanized areas) and other selected characteristics. Universe data fully reflect all open-to-traffic public roads in the State and contain basic information for planned, un-built future NHS. Universe data can be reported in either of the following ways:
Urban Areas: All urban places (or clusters) of 5,000 or more population and Urbanized areas. These are the small urban and urbanized areas within the State.
Urbanized Areas and Codes: Areas with a population of 50,000 or more, as designated by the Census. An FHWA-approved adjusted urbanized area includes the Census urbanized area plus transportation centers, shopping centers, major places of employment, satellite communities, and other major trip generators near the edge of the urbanized area, including those expected to be in place in the near future. Urbanized area codes are included in Appendix C. For multi-State urbanized areas, each State must report HPMS information for the portion of the FHWA-approved adjusted urbanized area within its State boundary. Area revisions as needed should be submitted especially shortly after the latest Decennial (or special) Census information becomes available. New codes for new or modified areas will be issued based on Census changes.
U.S. Territories: The U.S. Territories include American Samoa, Guam, the Commonwealth of the Northern Marianas, and the Virgin Islands of the United States. The Federal Information Processing Standard Codes (FIPS PUB 5-2) are included in Appendix A.
Vehicle Distance Traveled: This term refers to vehicle-miles/kilometers traveled.
Weighted Average: An average of a group of positive values where each is assigned a weight. For example, the user desires to find the weighted average of group of IRI values collected for a group of sections.
Value: 100, 109, 130, 140
Length: 1.233, 1.566, 3.555, 7.100
To find the weighted average: Compute the average using the length of each section as the weight. Get the sum of the products of each value times its section length. Divide the sum of the products by the total length of the group of sections. The weighted average in this case is 130.
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