Highway Performance Monitoring System (HPMS) Overview

The Highway Performance Monitoring System (HPMS) is a national level report required to submit by each state to the Federal Highway Administration (FHWA) each year. The FHWA requires this as a responsibility to maintain data and system performance for roads and highways in the United States and its territories. The HPMS is the way FHWA can record this data as well as portion federal funding to states for transportation needs.

HPMS can be summarized as an inventory of information on all public roads for the state. It is a measure of data including, extent, condition, performance, use and operating characteristics. It uses data gathered from the state and local agencies to evaluate different variable of roads and highways, specifically, all public roads and highways. Private roads and impassable roads are not counted for HPMS.

For an in depth document on all details involved in HPMS, click  here  to read the HPMS field manual.

There are 70 items total that are required to be reported on in HPMS. This ranges from pavement condition to lane width. These items are also required to be reported within certain data extents. Some are required to be reported in full extent (FE) and others are reported in Sample Panels (SP). When you see "FE+R", that means it is reporting full extent data with ramps.

States are also required to submit Certified Public Mileage (CPM). These are a calculation of the total length of a public road mileage in the state. these miles are delimited using different calculation methods, this includes different variables within each. There are centerline miles, which are the miles on a roadway that do not count the number of lanes, through lanes, which are the number of lanes on a given roadway, and lane miles, which is calculated by taking the centerline miles and multiplying them by through lanes. An important note to CPM and lane miles is that it only includes road lengths itself, excluding features like, turn lanes, shoulders, ramps, etc... The measure that includes all of the features on a roadway are called maintained lane miles.

There are many concepts that make understanding what is necessary to fulfill HPMS requirements difficult. The following are some core concepts to understand for HPMS and a brief overview of each.

Data Extent: There are 3 types of data extent, full extent, items reported system wide, sample panels, randomly selected sections of roadways that are used to represent various attributes at a system wide level, and summary data, more general information about different variables to report on. Depending on the facility type and classification of a roadway, the data must be reported in a specific extent. For example, Interstates must always be reported in full extent, as in, they must be reported system wide.

Federal Functional Classification (FFC): Federal Functional Classification is a list of 7 identifiers that describe the character of servicer of a roadway. These classifications are categorized in descending order from largest, to smallest. Note largest to smallest does not refer to any one variable, but is dependent on a myriad of different variables such as, traffic volume, population, carrying capacity, etc... These classifications are, Interstates, Other Freeways, Principal Arterials, Minor Arterials, Major Collectors, Minor Collectors and Local Roads. These classifications can change from year to year, however, typically only Minor Arterials and below change. Interstates do not ever change classification and only Major Collectors and up may receive federal funding.

Urban Code: This plays into FFC and is also a data item required to be reported on in HPMS. It is information from the US Census Bureau that is used to hypothesize traffic data and volume on a roadway. once the census areas are received, they are adjusted for transportation purposes. This results in inclusion of roads, intersections, etc... that may have been left behind in the orginal census areas. Urban code usage can be a valuable way to see changes in urban patterns, which can dictate traffic through a particular road. This could act as a good indicator for a possible change needed to a roadway's FFC.

Traffic Monitoring: Traffic Monitoring is incredibly important when it comes to HPMS, as funding is strongly based upon states traffic data. The requirements for Traffic Monitoring data include, vehicle classification, traffic volume, traffic counting and Annual Average Daily Traffic (AADT).

AADT: Annual Average Daily Traffic is a measure of traffic through the year. This tracks traffic volume and traffic seasonality.

VMT: Vehicle Miles of Travel are a measure of the total amount of miles travelled in a year. This is calculated by taking AADT and mile length for a specific section and summing them by all sections being used. A key point in VMT is that it is the daily average, not yearly. For yearly averages of VMT, the daily calculation is multiplied by 365.

Facility Type: This is the operational characteristics of a roadway. It is used for determining public road mileage, calculating capacity, and estimating roadway deficiencies. There are 7 different types of facilities a roadway can be categorized as:

One-Way Roadway: A roadway where traffic is moving in a single direction during non-peak hours.

Two-Way Roadway: A roadway where traffic is moving both directions during non-peak hours.

Ramps: A non-Mainline junction or connector facility contained within a grade-separted interchange.

Non Mainline: All non-mainline facilities excluding ramps.

Non Inventory Direction: Individual road(s) of multi-road facility that is not used for determining the primary length of or the facility.

Planned/Unbuilt: Planned roadway that has yet to be constructed

It is important to know that only one and two way roads are used in determining public mileage. while all of those codes must be reported on, any non-mainline type roads are not counted when reporting for HPMS.

Sampling is a very complex part of HPMS, but imperative to it. Sampling is taking a section of a particular road and using it to represent a larger area or roadway. To keep record of areas where samples could be useds, is called Table of Potential Samples (TOPS). In HPMS, TOPS is used to identify sample panels throughout the public road system. TOPS are based on five key data items, AADT, Functional System, Urban Code, Through Lanes and Facility Type, where these different types of data are unchanged on a given route.

Still need help understanding the basics of HPMS? Contact the Arizona Department of Transportation, Multi Modal Planning Division for more information on HPMS. You can also read the HPMS Field manual available  here. 

If you would like more information about different variables required for HPMS, feel free to visit another story map like this below:

 Lane Miles vs Maintained Lane Miles 

 Certified Public Mileage 

 Federal Functional Classification 

 Traffic: How is it reported? 

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