U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC 20590
The Highway Performance Monitoring System (HPMS) was developed as a systematic measure encompassing the scope, condition, performance, use and operating characteristics of the Nation's highways. It is a national transportation information system and is reflective of all public roads.
One of the most significant and visible uses of State-developed information submitted through HPMS is for the apportionment of Federal-aid Highway Program funds to the States. The HPMS also serves as a primary input mechanism for the biennial Conditions and Performance Report to Congress, which supports the development and evaluation of the FHWA's legislative, program, and budget planning. Additionally, HPMS serves as a primary resource for:
In addition, the HPMS serves the needs of the States, Metropolitan Planning Organizations (MPOs), local agencies, and other customers in assessing highway condition, system performance, air quality trends, and future investment requirements. Many States, MPO's, and local governments rely on traffic and travel data from the HPMS to conduct air quality analyses to determine air quality conformity and to assess highway investment needs using Highway Economic Requirements System - State Version (HERS-ST) or other similar analytic software. Finally, this information is an invaluable source of information for FHWA's annual Highway Statistics and other media publications. As a result of all these applications, States have an additional interest to maintain and assure timely, complete, and high quality data.
FHWA receives processes, analyzes, disseminates and uses information provided by the States through HPMS. The data States provide though HPMS are considered their data, not FHWA's. The quality and integrity of these data rest with the States and are dependent on their processes and procedures used to collect and create the basic data inputs. The questions, concerns and criticisms that come from the varied information customers reflect directly on the States' ability to accurately portray the condition and performance of their highway systems. FHWA provides guidance, training and technical assistance to States, and must assure that they provide quality data.
The FHWA Division Office (Division) provides an invaluable stewardship and oversight role in the collection, processing and submittal of the States Highway data as reflected in the HPMS. In the era of MAP-21 and evolving Performance Measures, the Division performs a pivotal role in assuring that data provided by the State is of the highest quality sufficient for FHWA business needs, accurately represents conditions in its State, and was collected and reported correctly. Furthermore, measuring how well the Federal-aid program is allocating resources in each State, assuring that each State receives its fair share of federal funds, and assuring that the investment needs of each State are accurately portrayed to the Nation's leadership is an important responsibility that involves the Division Office. This requires that the Division partner with its State to assure that the data provided are the product of a comprehensive, effectively managed and adequately funded data collection and reporting process, and the data provided to FHWA is timely, complete, accurate and of good quality.
FHWA headquarters provides an overall coordination role in the HPMS process. Reporting standards are set out in the HPMS Field Manual and reporting software has been developed and provided to the States via the User Profile and Access Control System (UPACS). Technical assistance, guidance and training are regularly provided to Division Offices and the States, and data are reviewed against prior year reports, normative trends and other States to identify possible improvement areas. However, no amount of Headquarters review can make up for an informed and comprehensive review by the State data owners and the FHWA Division Office stakeholders of both the data and the business processes by which the data are produced.
These guidelines serve to provide direction and focus on productive and meaningful review activities for the Division Office to use in performing its annual reviews, identifying and prioritizing improvements, and preparing reports documenting findings and recommendations. The guidelines contain specific information on annual reporting requirements, review of program activity areas identified using a program risk assessment matrix, and detail guidelines for use in conducting program and process reviews of the more significant data collection activities covered by the HPMS.
The guidelines provide flexibility for the Division Office to decide which data areas to focus on to improve the quality of the State's HPMS program. Each Division is responsible for developing, prioritizing, conducting and reporting on appropriate data program and process review activities. These guidelines should assist the Division in deciding the priority of process reviews to be conducted to ensure that all identified high priority data issues are thoroughly resolved as part of FHWA's ongoing data quality initiatives. They also provide detail questions and assessment criteria covering the data reporting areas considered to be of the highest priority for assuring quality data in HPMS. Technical assistance from the FHWA Resource Centers and Headquarters is available and should be considered as needs arise.
The FHWA Division Office also shares in the overall responsibility of providing quality data in HPMS. There are many activities that the Division can undertake throughout the year to support the State's program to provide timely and quality data in HPMS. In addition to maintaining a rapport and partnership effort, some of these activities include:
The annual review of the HPMS program by each Division Office includes four components: (1) Status Report and Certification, (2) HPMS Program Activity Assessment, (3) documentation and discussion of review activities identified through either the status report or program assessment, and (4) annual reporting. These are discussed further in the following sections.
This is a summary of activities and actions that have been completed within the past year by the Division Office and the State to be documented on the "FHWA Division Office HPMS Review – Status Report & Certification" form. Additional information as appropriate should be provided to further explain the summary information noted. The references to the review reports available on the HPMS web site can be used to aid in responding to specific data item quality issues. The response to Headquarters submittal comments is only one entry on this form – a reply is encouraged shortly after receipt of comments, and should not be the extent of the Division's review. The bottom of the form includes the annual certification statement that the Division Administrator (or Acting/delegate) is asked to sign. Please note that this statement includes all data in HPMS used for the major business needs of FHWA and refers to more than just the acceptance of mileage and travel data for apportionment of Federal funds.
This matrix identifies the major activity areas that are also included on the Status Report & Certification form that serves as a risk assessment of the State's HPMS program. This form "HPMS Program Activity Risk Assessment" should be completed based on the Division's knowledge of the State's program and review of the reports referenced for each data item in the activity column. It focuses on the quality of the data submitted, referring to Headquarters review comments, the data presented in the referenced reports, and Division review activities in the past four years. It should not be viewed as an evaluation of the State's program but as an aid in identifying which areas may need further attention where improvements may be realized. The rating information should be used to identify and prioritize activities for further review.
It may be advantageous to jointly complete this form with the State to provide a more accurate assessment, especially if the Division Office staff is new to HPMS, and to provide valuable information to the State. This assessment may help the State maintain or secure additional resources to address the issues identified to improve its HPMS program. The assessment can provide useful information when discussing the State's program to support those areas that the Division has determined need further review and possible improvement. An activity producing quality data may still be improved for efficiency even though no major data issues are evident in FHWA's review and edits of the data. Program efficiencies and enhancements can more easily be identified if a thorough review is conducted on the recommended three year cycle. A periodic review would be beneficial to both the FHWA and the State, considering the advances in technology for data collection and processing, frequent staff changes without complete State HPMS program documentation, and limited or reduced resources to provide the same level of detail and extent of data collection.
The seven high priority activity areas are listed below with additional guidance on reviewing each area available in the Attachments:
It is recommended that process reviews be conducted on these high priority areas as HPMS Program Activity Assessment scores warrant unless a schedule for improvement or change has been developed and is being implemented, or if any major deficiencies are identified that need timely resolution. An initial review may be necessary to establish a base line for these activities, which later can be addressed individually or scheduled over several years. These reviews should not focus on just the comments provided by Headquarters, which is a separate activity frequently requiring more immediate discussion, resolution, response or resubmittal of data.
Most of these priority areas are a continuation of prior review guidelines focusing on those areas that will provide the most effective use of Division Office resources to maintain and enhance data quality. The quality assurance activity addresses the past reviews of actual visual on-site field reviews of individual data items on sample sections, the submittal software "Validation Summary Report", and the State's quality assurance program. The data collection activities on off-state system facilities are included with each of the activity areas rather than listed separately. The highway capacity data and VMT review items are included under Traffic Data. The review of traffic data should focus on the State's data collection program and the process for updated current year traffic data in HPMS, since review of HPMS traffic data is a key component to determine acceptability of the data submitted. The review and documentation of the State's Traffic Monitoring Program for Highways (TMS/H) is only one component of the traffic review and should not be the only activity reviewed, as discussed further in the Attachments.
The scheduling of process reviews for high priority areas should be determined by the Division, in concert with the State, based upon the ranking of activity areas and considering those that have the greatest need for improvement. Assistance in conducting process reviews can be provided by Headquarters, the FHWA Resource Centers, Division Office program specialists (pavements, traffic, ITS), and other States as a review team approach. The teaming of FHWA and State resources is a way to foster knowledge sharing, to use available expertise for thorough and comprehensive reviews, and for effective monitoring of improvements.
Review activities undertaken the past year by the Division that was identified through either the Status Report or Certification or the HPMS Program Activity Assessment should be documented and provided for Headquarters information. This provides valuable information on Division review efforts and further explanation about the State's HPMS and data collection programs. This can include discussion of comments on the Status Report and Activity Assessment forms, status of process reviews either initiated or completed, and other relevant data collection information. The level of detail is determined by the Division and can range from summary information to detail reviews, guidelines, schedules, team charters, work plans, action plans and resource commitments.
The Division Office is responsible for providing an annual certification and supplementary information on its annual review, which should be officially transmitted to Headquarters (HPInfoMail electronic mailbox, cc Joseph Hausman) by December 15 of each year. This information shall consist of the above discussed three areas: Status Report and Certification HPMS Program Activity Risk Assessment, and documentation and discussion of review activities completed during the past year.
The review memorandum or supplementary information should also document any FHWA actions taken or recommendations made as a result of the review, and steps the State is taking to make HPMS program improvements. Follow up reporting by the Division of issues, recommendations and results on a year-to-year basis are essential to staying on the path to quality improvement over time. And, in an era of rapidly changing staff and responsibilities, it is important to maintain an adequate record of progress.
It is important that reviews be performed in a timely manner so that results and recommendations can be implemented before the State starts its next data submittal. This provides time for further discussion with Headquarters and for the State to improve processes or data collection efforts if needed. Starting a review early in the year allows for: sufficient time for discussion and, if necessary, adjusting resources and priorities in developing the next State Planning and Research (SPR) Work Program, and; availability of sufficient information without waiting for the current year data submittal or review comments from Headquarters. The Division's review activities can be included in the Division's annual work plan and review schedule for the coming year to ensure all participants are identified and available.
Data, review comments, and identification of issues should be readily available to the Division and State even before Headquarters current year review comments are transmitted. This information includes past Headquarters review comments, the State's submittal comments, validation summary reports from the HPMS software, HPMS website tables and reports, Division knowledge of the State's HPMS and data programs, and frequent SPR work program progress and performance reports.
Whenever a review is performed, the Division must address adequacy of funding for the HPMS program for both the State and any other entities providing data. The adequacy of personnel, equipment and training needed by State and local agencies to conduct the HPMS program in a quality manner should be examined by the Division. Resolution of high priority data issues should be a factor in determining priorities for funding of activities in SPR and Unified Planning Work Programs (UPWP).
With the release of the HPMS 8.0, spatially enabled web-based software tools have been provided to examine the quality of data submitted by the States. The Divisions are encouraged to become skilled with the HPMS software to facilitate the reviewing of their State's data and for conducting process reviews of critical data areas. The Divisions should make full use of the HPMS Field Manual, resource information on the HPMS web site, and examples of other Divisions' outstanding reviews as a resource when developing and coordinating data and process reviews. The HPMS team stands by to provide training for any FHWA Division personnel as needed.
Information and Analysis is a key criterion which FHWA uses as a measure of our agency's performance to determine if we are meeting the needs of our customers, States, Congress, and the public in providing quality data which accurately represent the travel characteristics and extent of our Nation's highway system. How we effectively manage the quality of data in the HPMS has a direct impact on FHWA's ability to assess our progress in meeting agency performance objectives for the Strategic and Annual Performance plans. The proactive assistance of the Divisions and Resource Centers in working with the States and MPOs on improving the quality of data in HPMS should be a critical component of planned Division and Resource Center work activities. Improving data and processes for HPMS should be included in the Division's performance plan objectives and self-assessments and should be accomplished by working with the State DOTs and MPOs. We encourage the teaming of Division, Resource Center, Headquarters and State staff to maintain and improve the quality of data in HPMS, and to provide an opportunity for knowledge sharing as part of meeting our agency goals of developing high quality highway information for our customers. With the implementation of the HPMS 2010+ system, a fundamental change in HPMS has taken place. Geospatially enabling HPMS gives us another way to review the system. Samples as well as all sections can now be seen and, at the reviewer's option, the data can be reviewed while still in the office.
(Annually by December 15th, complete and sign this form, the risk assessment, and attach additional information as necessary.)
STATUS REPORT – Answers (Y/N) to these questions should be reflected in rating each activity on the HPMS Program Activity Risk Assessment form (Page 8).
____ State maintains an accurate, up-to-date – as driven – GIS/LRS.
____ The LRS/GIS represents and correlates with the State's Enterprise Management Systems.
____ Federally-Aided Routes are included.
____ All Public Roads are included (ARNOLD).
____ State completed its data submittal by June 15 with no major deficiencies.
____ State's submittal letter adequately explains recurring conditions, edits, changes and improvements being made in data collection procedures and processing data?
____ The HPPI Data Memo has been fully discussed and understood by both the Division and State?
Dated response forwarded to OHPI including discussion of implementation _________________
Resolution of other comments in correspondence and discussions ________________________
____ Current levels of SPR funding are adequate.
____ State has requested additional resources for data collection, system improvement or staffing.
____ Process improvements identified, reflected in an action plan, and fully supported in SPR or State work programs.
____ The State has a quality assurance program concerning all data provided for HPMS.
____ The data reported in HPMS directly reflect current enterprise information systems.
____ A Field Inventory Review has been conducted within the past year to verify data is coded properly and reflects current conditions, and all problems/issues have been rectified.
____ Have all the necessary counts taken place on the Federal-Aid System to accurately represent traffic volume for the data year, per the TMG? Do traffic volume trends reasonably reflect ATR data?
____ Do the trends in VMT by functional class appear reasonable compared to adjoining functional class groups and prior year's data?
When was the last time your office did a process review of the State's traffic monitoring program to assure that procedures are adequate and are being applied to all data for HPMS? (This is more than just the TMS/H review; it should follow the guidelines in Attachments D and E.) _______________
____ IRI data been provided and updated within the last 1 or 2 years as required.
____ When was the last time your office did a process review of the State's pavement data program to assure that procedures are adequate and are being applied to all data for HPMS? __________________
____ Is the State maintaining the locational integrity of pavement data over time?
____ The State conducted a sample adequacy review this year, explaining results and changes in number of samples or when last review was conducted.
When was the last time your office did a process review of sample adequacy to assure that procedures are adequate and are being applied to all data for HPMS? __________________
The following apportionment factors for the Federal-Aid Highway Program are derived from HPMS. They can be found in the HPMS 8.0 software, Extent and Travel Report. Please verify this information and enter it below. Each FHWA Division must certify that this information as reported in HPMS is accurate and verified.
FC = Functional Classification
Interstate Principal Arterial, FC = 1
Non-Interstate Principal Arterial FC = 2, 3
Principal Arterial FC = 1, 2, 3
Federal-aid Highway FC = 1, 2, 3, 4, 5, Urban 6
|I certify that the State's HPMS submittal and the information in this review are true and correct to the best of my knowledge and belief and there is no evidence of submission of false data, which would be in violation of U.S.C., Title 18, Section 1020. Furthermore, I certify that this data is valid and suitable for use in the apportionment of Federal-aid highway funds, performance measurement, and condition and performance reporting to Congress.|
|______________________________________ FHWA Division Administrator||______________________________________ Date|
|GIS/LRS Adequacy. Met ARNOLD Requirement||GIS/LRS is not adequately maintained and/or does not reflect the entire Federal Aid System. An All Public Road, Dual Carriageway GIS/LRS was not submitted.||GIS/LRS is maintained and does reflect the entire Public Road System. May not be integrated with the DOT Enterprise or completely up to date. Local Road LRS may not be tested or attributed.||GIS/LRS is maintained and does reflect the entire Public Road System. It is integrated with the DOT enterprise but may not be completely up to date. All dual carriageway (divided) roads may not be represented. The Local Road LRS is tested and can be attributed.||GIS/LRS is well maintained and does reflect the entire Public Road System with dual carriageways. It is integrated with the DOT enterprise and is completely up to date. The entire network is used as the primary roadway component to a Statewide geospatial framework.|
|Data Submittal||Late with incomplete mileage and VMT data, other major data issues are not explained.
Submittal comments are brief and general. Many resubmittals have occurred.
|By June 15th , complete mileage & VMT data, major issues explained or data resubmittal.
Submittal comments are not adequate to explain all issues identified. 1 or 2 resubmittals have occurred.
|By June 15th, complete data and minor observation comments.
Submittal comments explain recurring validations and any other issues. No more than one resubmittal.
|By June 15th, no negative observations or comments.
Submittal comments explain minor issues, edits, and changes in procedures and processes. No resubmittal.
|SPR Work Program||Decreased or inadequate funding or no priorities for data collection, including staff, training or equipment||Adequate funding, some recognition of needs and new activities, but still no changes in staff, training or equipment.||Adequate or increased funding, more staff and training for selected activities, achieving HPMS Field Manual Data Requirements.||State's data program efforts are well funded, fully supporting all data requirements as described in the HPMS Field Manual.|
|Quality Assurance||Minimal quality assurance, off-state system issues, many coding error messages.||Basic quality assurance program for short term solutions including off-state system issues, some coding error messages explained in submittal comments.||Quality assurance program implemented and coordinated with all data providers, minor isolated problems.||Quality assurance program documented, funded, and no major data coding problems found. Data quality is assured prior to loading in the HPMS software.|
|Traffic Data||Current year data provided with no statistical or verifiable explanation for anomalies and unusual trends for many locations. Many OHPI comments. Many unusual/unexplained travel/traffic issues.||Current year data provided with acceptable statistical justification for anomalies and unusual trends locations. Local Road summary data is submitted but may have statistical or trend issues. Still have many OHPI comments.||Current year Traffic/Travel data provided for Federally Aided highways, and Local Roads (Summary). Acceptable statistical justification for anomalies and unusual trends. Minor/few OHPI comments.||Current year Traffic/Travel data provided for Federally Aided highways, and Local Roads (Summary). Trends are consistent and the data is statistically accurate. No OHPI comments.|
|Pavement Data||Complete data provided, on-state system updated on an infrequent cycle, off-state system data incomplete, and many OHPI noted issues. Does not meet MAP-21 based performance measure requirements. SPR focus is necessary.||Complete data provided, on-state system updated on a 2 or more year cycle, plan developed for complete off-state system data, many OHPI noted issues, still does not meet MAP-21 based performance measure requirements. SPR focus may be required.||Complete data provided and collected with supporting explanations where data differs from the HPMS Field Manual guidance, all current 1-2 year data. Few OHPI comments. Marginally meets MAP-21 based Performance measure requirements. SPR focus not necessary. The appropriate pavement data items are being reported in 1/10th of a mile sections.||Complete data provided and collected in accordance with Field Manual, all current 1-2 year data, where required, No OHPI comments. Fully meets the performance measure requirements as intended under MAP-21. The appropriate pavement data items are being reported in 1/10th of a mile sections.|
|Sample Adequacy||Many samples have not been developed where required (sample adequacy); some volume groups have no samples where at least one is required. Many samples are not populated with the required sections data. Many OHPI comments/ concerns.||An incomplete sample panel has been submitted, the adequacy issues are minor. A few Volume Groups still have no samples developed where at least one is required. Spotty necessary section data has been provided to fill the samples.||A full Sample panel has been developed; e.g., the panel is fully adequate. Still some minor sample populating issues.||Sample revisions not needed or were made addressing all deficiencies and OHPI comments. Samples are fully populated.|
|Total Score (140 max)|
|Activity(ies) Identified for Review: (Less than 10, more than one activity should be considered)|
State: Date Year (Attach to your Status Report & Certification) Date of Assessment
The activity with the lowest points should be considered for further review following the guidelines in the Attachments. If scores are similar to prior year's assessments, history of continuing issues, or OHPI comments should be considered in selecting activities for your further review.
The Report references are on the FHWA HPMS web site for each State https://www.fhwa.dot.gov/policyinformation/hpms.cfm. Attachment A provides guidance on how to access these reports.
The Attachments C through H provide guidance on reviewing each activity in detail that may need to be tailored and customized to adequately support a comprehensive process review addressing the particular issue or program area.
Acronyms used in Risk Assessment Form:
|Field Manual||HPMS Field Manual|
|H.V.||High Volume (AADT)|
|OHPI||Office of Highway Policy Information|
|PAS||Principal Arterial System|
|SPR||Statewide Planning and Research program|
|VMT||Vehicle Miles Traveled|
The HPMS Submittal Comments are entered under the Submit Data tab in the HPMS 8.x software. The purposes of the comments are to explain data issues, problems, deficiencies, unusual conditions, and any significant changes from the previous HPMS submittal. If no comments are found in the software, please contact the appropriate HPMS staff for further discussion/clarification.
The Submittal Comments are intended to address recurring or new issues on unique conditions in the State, problems, deficiencies, program and process changes, future activities proposed to improve data quality, and significant changes from the previous HPMS submittal. Does that State address these issues and are there other activities that should have been discussed? Specific issues that can also be addressed in this file are the following:
Explanation of software messages, errors and that the State feels is correct or needs further explanation
Issues and processes affecting the data for HPMS and its quality
FHWA Headquarters comments on last year's data submittal
Discussion and listing of sample revisions, deletions and additions
IRI/Pavement data collection procedures
Traffic monitoring activities and procedures
Urban boundary and functional classification changes
Comments on reports on FHWA web site
Mileage reporting for certified mileage, system changes, and Federal lands
Summary data of population and net land area
Comments on full extent data items
Override of peak capacity values
Pictures of unusual or unique roadway conditions
Identifying HPMS and other State contacts
As part of an in-depth review of the SPR (Statewide Planning and Research) Work Program, activities that could be investigated and comment on include the following:
Does the current year program have sufficient resources allocated to HPMS and data collection? This would include data collection equipment, computer software and hardware, training, travel, and participation in FHWA workshops. Are these activities described in the program? Does the description accurately represent tasks that are underway today or proposed for future years?
Is there adequate staffing available for HPMS and data collection programs?
Are there consultants involved in data collection or reporting of HPMS data items?
Do the Metropolitan Planning Organizations (MPOs) or other Local Government entities collect data reported in HPMS and is it described in either the SPR or PL work programs? Is there a formal agreement, memorandum of understanding, or guidelines provided specifically for their use, are they accountable?
What is the budget amount for HPMS in the SPR or State planning work programs? This would be the principal staff or those associated with the annul HPMS submittal and not necessarily those involved in data collection. What is the consistency of the current funding level for the past several years? Is funding expected to increase?
Are there SPR, PL or Safety Funds used for MPO data collection activities supporting HPMS? What are these funding levels?
Does the State supplement the SPR work program with State only funds? Describe these activities, the funding levels, and your involvement in monitoring and supporting them.
Do expenditures track closely with programmed funds? If not, what is being done to emphasize the need for resources to be expended on these activities?
Do large unobligated balances of funds exist? Some of these may be saved for next year's program. Are all data collection programs and activities to support Title 23, USC, Sec 502 being adequately addressed?
What is being done to increase funding for data collection improvements if deficiencies in these programs have been identified?
Have past comments from OHPI been discussed in the development of the work program and have changes resulted in the program to support these comments?
Are comments and recommendations presented in writing to the State on the draft program or in the approval of the final program?
Are recommendations from process type reviews and action plans reflected in the SPR work program?
Are improvements or future HPMS and data collection review activities discussed?
Is there formal correspondence to the State on approval of SPR Work Program? Comments could be made on high priority activities, acknowledgement of successful efforts, and offering support.
Describe the monitoring activities of the Division to assure that funds programmed are being spent accordingly. Are their progress meetings periodically throughout the year? Does the planning staff review final expenditure and performance reports before the project is closed out or before next years program is developed and or approved? How is the program monitored: quarterly, periodically, frequent meetings, reviewing billings?
Please keep in mind that data collection activities are important to the FHWA programs. If necessary the FHWA Division Office may need to step in and prioritize the SPR program.
A quality assurance program can assist the State in continually providing quality data for the HPMS submittal. This program generally consists of various activities used to verify that data in the State's database and subsequently data in HPMS are accurate, current, and representative of the State's public road system. This program can also rely on the Division Office Field Reviews to spot check coding of various data items by physical observation or other methods. To assess quality assurance of data in HPMS the following three activities should be reviewed:
Does the HPMS Validation Summary Report contain many fixable errors?
Has adequate justification and explanation been provided for these errors in the State's submittal comments?
Are there continuing errors (over many years) that require a change in procedures or processes?
What progress has been made in addressing these error messages?
Are there fewer messages each year?
What is being done to eliminate these messages?
What are the State's management goals and philosophy for quality data? This should be more than just editing data and can include such activities as sharing, partnering, cost, duplication, and coordination.
Does the State have a quality control program and what are the basic components of the program?
How current is the program and when was the last time it was updated?
Is it thoroughly documented? Please attached or provide a link to the documentation.
Is there a sampling plan and does it fully satisfy the HPMS 8 requirements, confidence levels, and annual monitoring and reporting?
Does it show or document that data quality has been improving?
How are training, follow up, and monitoring of the quality control program accomplished to make sure it is effective and still useful?
Are the HPMS software edit routines used or are there internal data checks (recommended) and comparisons?
Does it apply to just data for HPMS or to all data in the State's database?
Describe how it improves HPMS quality?
Does it include off-state system data collected by other agencies? If so, what assurance is made of the quality of this data reported by others? What feedback and assistance is provided other agencies?
Describe the FHWA Division Office involvement in the State's quality assurance program? This can include submittal procedures, computer hardware and software activities, monitoring equipment maintenance and updating, resource needs, and data integration programs.
A Field Inventory Review should consist of a mixture of onsite visits and remotely viewed, randomly selected section locations (See your HPMS coach for help if needed, selecting the random samples) to verify that the data reported represents current conditions and is accurately coded in the State's most recent HPMS submittal. This is most effective if conducted jointly with the State to add credibility to the findings and to discuss conditions and interpretations as they occur in the field. The HPMS training materials or web site can be used as guidance in the proper coding of data items.
A check should be made on a minimum of 30 sample and 30 TOPS (potential samples, see HPMS Field Manual) sectionsdivided between Interstate, Non-Interstate NHS, and other arterial and collector systems. All visible section information should be verified and the State should provide evidence of non-visible data items. Both field visits and remote viewing (e.g. photolog, aerial photos, Google Earth etc.) methods should be used for the review of the roadways. If the Samples are reviewed remotely, care must be taken to make sure that the source material is concurrent with the year of the data reviewed.
The findings should be discussed and presented to the State to determine if procedure changes are necessary for the collection, processing, or coding of specific data items. Discuss responses to your findings and what actions will be taken for resolution.
Verification that changes have been made may need to be performed on an ongoing basis and reported to HQ.
The findings of the field review may result in changes in the State's quality assurance program. This can also be viewed as a review of the State's quality assurance program (assuming they have one) to verify that it is working and if improvements are needed. Discuss how this has improved the quality assurance program.
The review of traffic data could focus on several traffic monitoring activities, which affect many data items. These activities include the traffic monitoring program, travel data (VMT), vehicle percentages and highway capacity related data.
To assist in determining which traffic activities to review, other than those issues and comments highlighted in the past, it is suggested that periodically a detail review of the AADTs reported in the State's submittal should be made. The Attachment E flowchart "Review of Traffic Data Submitted for HPMS" should aid in this review to determine if AADTs were calculated properly using the State's procedures and meeting the requirements of HPMS. The accompanying narrative to this flowchart should supplement and further describe many elements of the State's traffic monitoring program as presented in this attachment.
Status of Traffic Monitoring System for Highways
Has the Traffic Monitoring System for Highways (TMS/H) program been thoroughly documented and accepted by FHWA? Comment on recent updates and future improvements being considered.
Continuous Count Program
How many ATRs (Automatic Traffic Recorders), urban and rural, are in use?
What seasonal pattern groups are developed and how many ATRs are there for each group? Does each group meet the 10 percent precision and 95 percent confidence level?
To the extent possible, is there one ATR on each route of the PAS/NHS?
Are there at least 3 ATRs on both the rural and urban non-Principal Arterial routes?
For each ATR, is a minimum of 7full days of data for each day of the week for each month collected?
How many ATRs in the system (urban/rural) are used for the development of adjustment factors?
Manufacture's names of ATR systems (sensors and recorders) being used?
What accuracy checks are made of the ATR setups and the data being collected?
Describe the State's processing of ATR data, including editing procedures, automation and software, and missing data procedures.
Do MPOs, TMC's or other agencies have a continuous count program? Describe the content and extent of this program and how it is used by the agency and State.
In General does the State's Continuous Count Program model the State's overall travel trends as reflected in the TMAS 2 Growth Factors Report (GFR)
Coverage Count Program (Division should check the HPMS 8.0 Metadata)
Which roadways are included in the State's coverage count program?
Does the State's coverage count program cover the entire NHS and all functional classes above collector?
Are the State's traffic volume counts made on at least one third of the HPMS sample panel by functional class each year? Are the rest of the locations counted on a 6-year cycle?
Is the duration of all traffic volume counts a minimum of 48 hours (required)?
How many 48 hour traffic volume counts are conducted by the State each year off the State highway system (urban/rural)? Are there at least one-third of the total counts required on a three-year cycle?
What traffic volume counting equipment systems are used by the State? What checks are made of the equipment?
Does the State include traffic counts collected by MPOs, ITS, local agencies and contractors? What is the schedule for these counts? How are they factored?
What procedures and controls are required for traffic counts collected by MPOs and others? Are these procedures and controls consistent with the TMS/H requirements?
What coordination is done with local agencies to ensure satisfactory procedures are used?
What procedures and controls are specified for the collection of coverage counts by contractors?
If ITS or freeway monitoring system data is being used, what is the process of verification, calculating AADTs, and quality control?
To determine if AADTs were calculated properly using the State's procedures and meeting the requirements of HPMS, a review should be made on a random sample of HPMS sections using the flowchart "Review of Traffic Data Submitted for HPMS" in Attachment E.
Describe the process used by the State to update traffic volume data for each HPMS submittal using all available State and other agency data.
If the HPMS section does not match exactly with the traffic counting section (in the State's traffic database) how are traffic volumes calculated and assigned to the HPMS section?
Is this an automated or manual process? Describe this process.
Vehicle Classification Program
Does the State stratify vehicle classification by type of area (urban/rural) and functional class?
Does the State allocate classification sampling to the above noted stratifications in proportion to the associated VMT for these systems?
Describe the State's vehicle classification activities in terms of number of counts (urban/rural), duration, and type (automated or manual).
How many counts are used to calculate axle correction factors (urban/rural)?
Does the State conduct vehicle classification by lane and in both directions?
Does the State distribute its vehicle classification sampling throughout the year to avoid the need for seasonal adjustments?
Describe the data retrieval and reporting activities and procedures.
What counting equipment systems are used? What checks are made of the equipment?
Vehicle classification activities on the NHS must be sufficient to assure that on no greater than a 3-year cycle every major system segment will be monitored to provide information on the numbers of:
To what extent does the State's classification program fulfill the above requirements?
In monitoring vehicle classification on the NHS, if it is determined that two or more continuous major system segments have both similar traffic volumes and vehicle type distributions, a single monitoring session will be sufficient to monitor these multiple segments. Does the State use this single monitoring session approach?
What is the State's program for meeting the TMG guidance on 30% of all volume counts being vehicle classification counts?
Number of vehicle types 13, 14, and 15? What are 14 and 15 used for if included?
What class or truck adjustment factors by season and day of week are used?
Adjustment Factors Procedures
What factors are used by the State (seasonal, axle, day of week) to adjust coverage counts?
Does the State review their adjustment factors annually and update them yearly?
Are the State's editing and adjusting procedures for converting short term counts to AADT documented?
Describe the State's practices and procedures for developing and applying seasonal adjustment factors.
Describe the State's practices and procedures for developing and applying axle adjustment factors.
Describe the State's practices and procedures for developing and applying day of the week adjustment factors, yearly adjustment factors.
Does the State apply these same adjustment factors to coverage counts provided by MPOs and other agencies? If not, do other agencies apply factors to data collected and what are these factors reviewed and accepted by the State?
Documentation of the vehicle classification program should demonstrate that:
Does the State's vehicle classification program satisfy the above requirements?
How many classification sites are used to calculate axle correction factors?
Describe the State's development and application of growth factors.
Procedures and Activities for Equipment Testing, Documentation, and Data Retention
Describe the State's requirements for testing of equipment used to collect traffic data.
Describe the State's documentation of its data collection procedures. Does the documentation specify the following?
Describe the State's source data retention.
How often do the State and MPOs update documentation of their traffic monitoring procedures? How current are the existing procedures?
Funding and Personnel Support for Traffic Monitoring Program
Describe the current funding and staffing of the State's traffic monitoring program(s) and activities. FTE's vs. FTE's/1000 counts
Describe future program improvements (ex: additional resources, equipment acquisitions, data processing changes, research activities, additional volume counts/ classification counts/WIM's, etc.).
Travel is calculated from traffic data and corresponding section lengths entered into the HPMS database. Travel by functional system and specific Interstate routes should be reviewed for significant increases or decreases. Larger than normal changes, based on past trends, should trigger an examination of reasons for the changes and the reasonableness of the reported values. Reviews should address both reported length and traffic data for functional systems and routes examined. Issues to examine include:
Is total VMT by functional system reasonable for the reported year and are comparisons to prior years reasonable?
Are total rural and total urban VMT data reasonable and are trends consistent?
Determine if changes in VMT by functional system reasonably reflect recent annual trends within geographic sub-areas of the State.
Is functional system VMT by urbanized area reasonable based upon past trends and are comparisons among urbanized areas reasonable?
Compare reported VMT and MPO VMT estimates for consistency at the functional system and/or urbanized area levels.
Are HPMS generated VMT used for air quality conformity purposes in non-attainment areas? Are there unresolved issues or problems associated with their use?
Can significant changes in VMT trends be justified? Review the adequacy of the documentation supporting these travel changes.
Determine how changes in route miles are reported and documented by the State or MPOs or Cities. Do the route mile changes appear reasonable based on past trends? How does the State monitor local government mileage data changes?
Some of the more significant data items which contribute to the quality of highway capacity estimates include: percent trucks, turning lanes, at-grade intersections, percent green time, shoulder type and width, number of peak lanes, lane width, median width, median type, and K (design hour volume) and D (directional) factors
These factors are generally determined from ATR data. Statewide rural and urban K and D factors applied to all routes or to entire functional systems should only be used as an interim procedure if site-specific data is not available. The use of route specific factors for similar facilities, factors by functional system for individual urban or urbanized areas, or factors by route or functional system for State sub-areas having similar characteristics are acceptable if site-specific data is not available.
How often are K and D factors updated by the State and MPOs?
What is the process for calculating these data and assigning them to sample sections? Is the process the same for off-state system locations?
What are the factors being used and are they reasonable? Comment on the range of factors being used.
If improvements are needed in providing more site-specific data, what is the State's scheduled and plan?
How are the K&D factors calculated for 48 hour or 7 day counts?
These percent's are generally determined from vehicle classification data and applied to sampled roadway sections. Statewide rural and urban truck percent's applied to all routes or to entire functional systems should only be used as an interim procedure if site-specific data is not available. The use of route specific percents for similar facilities (characterized by truck routes, land use, geometrics, or other criteria), percents by functional system for individual urban or urbanized areas, or percent's by functional system for State sub-areas having similar economic activities and characteristics are acceptable if site specific data is not available. As the State is further implementing a vehicle classification program following the guidance in the Traffic Monitoring Guide (one third of volume counts should be classification counts) more site-specific data should become available each year.
How often does the State update percent truck data?
What is the process for calculating these data and assigning them to sample sections? Is the process the same for off-state system locations?
What are the factors being used and are they reasonable? Comment on the range of factors being used. How is truck data factored?
Is this data shared with MPOs and other agencies?
What is the State's schedule and program (1, 2 or 3 years) for meeting the vehicle classification program guidance in the Traffic Monitoring Guide?
Does the vehicle VMT developed from section data match vehicle VMT information derived from summary data (where applicable)
(Numbers refer to additional guidance on following pages)
Locations should be selected randomly using some criteria such as: past issues, distribution by functional class, functional class and VMT, high volume locations, on state and off state system, and a minimum of 15 locations. Sample and universe sections should be considered.
Was the AADT reported in HPMS based on an actual count taken with traditional traffic monitoring equipment located at the sample location? This would involve reviewing this location in the State's traffic database to see if a count was taken or if it is based on a count from an adjoining roadway section. If a count was not taken, was the AADT based on either of the other two acceptable methods, data from a freeway monitoring system or ramp balancing, which needs to be reviewed to determine acceptability. If the count was based on any other process or information, even if it used that year's data, it is not acceptable for HPMS reporting.
Was the AADT based on a traffic count taken the same year as the reporting year for HPMS? Current year data is required to be reported in HPMS; if this is not the case, then proceed to step 12.
This is typically referred to as an Automatic Traffic Recorder (ATR), which continuously monitors traffic 365 days a year. If this is not an ATR location, proceed to step 5 to determine the acceptability of shorter counts. A 365 day count is usually the most accurate count available based on continuous monitoring at the site. 365 days is the ideal with many locations oftentimes having some missing data. The amount of missing data needs to be reviewed to assure a minimum of 7 weekday counts each month are available. If there is missing data, how many days or months were missing, and was the count still used? This should be in accordance with State procedures and typically nine months of acceptable data is required to calculate a valid AADT from an ATR count. To calculate an AADT are all days averaged, are monthly ADTS calculated first then averaged, or is some other method used? If days are missing each month, the preferred method is to calculate a monthly ADT first for each month and then average all the monthly ADTs to get an AADT.
What Procedure was used to assure that less than 48 hour ADT counts produced adequate results?
The minimum counting period for all traffic counts is 48 hours. Lesser time is generally not acceptable unless this process is reviewed in step 11. Is the 48 hour count divided by 2 or is the preferred method of averaging the two 24 hour counts used?
For all short term counts (less than an ATR count) a seasonal adjustment factor shall be applied to adjust the count to an annual count based on travel patterns of similar facilities in the State. This factor is developed based on the grouping of ATR locations of similar travel patterns and statistical variability. These are typically factors for each month of the year based on specific groupings unique to your State. Was the proper seasonal factor applied for the month the count was taken as verified from reviewing the State's table of seasonal adjustment factors? If the proper factor was not used or the number doesn't follow the trend from prior years or adjacent months, then an in-depth review of the seasonal factor process should be conducted. The seasonal factor process should be periodically reviewed at least every three years: assistance for this review is available from HPM30 (Traffic Monitoring Division) in the Office of Highway Policy Information. The State should be reviewing this process annually and updating at least every three years.
For all counts less than 7 days (less than 168 hours) a day of week factor shall be applied to adjust the count for variations in daily traffic. This factor usually uses the same grouping of ATR locations as the seasonal adjustment factor groups. This factor adjusts the count to consider different travel patterns typically found on weekends (Friday, Saturday, and Sunday) which is not the time period most counts are typically taken. Sometimes the day of week factor is included in the seasonal adjustment factor discussed in step 6; this needs to be verified if separate day of week factors are not being applied. Was the proper day of week factor applied for the days the count was taken as verified from reviewing the State's table of day of week factors? If the proper factor was not used or the number doesn't follow the trend from prior years or adjacent days or weeks, then an in-depth review of the day of week factor process should be conducted. The day of week factor process should be periodically reviewed at least every three years; assistance for this review is available from HPM30 (Traffic Monitoring Division) in the Office of Highway Policy Information.The State should be reviewing this process annually and updating at least every three years.
For all counts taken that monitor vehicle axles an adjustment shall be made to convert axle counts to vehicle counts. Pneumatic road tubes or other sensors that only monitor one axle at a time typically count axles. If the sensors monitor all axles and axle spacings, or record vehicle length whereby the type of vehicle can be determined, then an axle correction factor is not necessary. An axle correction factor is usually developed from vehicle classification information at that location, adjacent roadway section, or for that factor group. Was the proper axle correction factor applied for the axle count taken as verified from reviewing the State's table of axle correction factors? If the proper factor was not used or the number doesn't follow the trend from prior years or adjacent factor groups, then an in-depth review of the axle correction factor process should be conducted. The axle correction factor process should be periodically reviewed at least every three years; assistance for this review is available from HPM30 (Traffic Monitoring Division) in the Office of Highway Policy Information. The State should be reviewing this process annually and updating at least every three years.
There shall be no other adjustment factors applied to an actual traffic count than the three described in steps 6, 7, and 8. Any other type of factor is not allowable which may include such things as equipment error, simultaneous vehicle hits on sensors, high or low volume adjustments, engineering judgment, or perceived errors. If any of these other non-allowable types of factor were applied, the AADT should be recalculated without these factors.
Was the AADT that was calculated after all adjustments were made rounded so a more general number could be reported? This is an acceptable practice, but not required, provided it is used consistently for all counts. Some States do not round ATR counts just so they can easily identify these counts in their database. Counts rounded for HPMS should also be rounded in the State's database as reviewed in step 14.
Counts that are for less than a 48 hour monitoring period shall be based on some statistical analysis conducted by the State to determine that there is minimal variability in weekday counts concluding that 24 hour are just as accurate as 48 hour counts. The difficulty of counting, lack of resources for longer counts, or the ability to count more locations are not acceptable justifications for providing counts shorter than 48 hours. Counts less than 24 hours are not acceptable. Imputing missing hourly information is not acceptable for any count.
The frequency of counting shall be atleast one third of all locations counted on a three year maximum cycle. If counts are older than three years then a recount or current year count is necessary unless the State has an alternate approved count cycle. Has this alternate approach been accepted by FHWA and reviewed recentlyto determine if it is still reasonable, documented, and acceptable. There may be locations with unusual volumes where this may be appropriate or where the data is obtained from sources such as freeway monitoring data, or other approved sources. Counts taken within three years shall be updated to reflect current year traffic using growth factors calculated by the State based on other count data as reviewed in step 13.
Growth factors shall be applied to all counts not counted in the current year so the AADT will reflect current year travel. Was the proper growth factor applied to the year the count was taken as verified from reviewing the State's table of annual growth factors? If the proper factor was not used or the number doesn't follow the trend from prior years or adjacent functional classes, then an in-depth review of the growth factor process should be conducted following the Process E Flowchart. If a proper growth factor was applied, then no other adjustments are necessary and you should proceed to step 9. The growth factor process should be periodically reviewed at least every three years; assistance for this review is available from HPM30 (Traffic Monitoring Division) in the Office of Highway Policy Information. The State should be reviewing this process annually and updating at least every three years.
The traffic data reported in HPMS shall be the same data the State uses for their own purposes as contained in their traffic database. If this data is different, a review should be made as to why the difference and the need for a resubmittal of traffic data from the State's database may be necessary. Using the same data provides some assurance that it was collected and processed properly following the State's traffic monitoring program and not processed independently for HPMS. This also makes it easier to compare outputs from the HPMS submittal with the State's data, such as trends in VMT, if the same data is used.
Is pavement roughness (IRI) data being collected on an annual cycle for highways designated as part of the Interstate system and NHS? If not, is a Plan of Corrective Action in place to correct?
Are the Pavement related HPMS data items being reported in 1/10th of a mile segments as required in the 2014 and later HPMS Field manual?
Is IRI being collected on Other Freeways/Expressways, Other Principal Arterials and Minor Arterial Sample Sections on a the 2-year maximum collection cycle? If not, what update cycle is used and what is the State's Plan of Corrective Action for meeting the 1 or 2-year HPMS cycle requirement?
Is other required pavement data collected as a byproduct of the roughness data collection effort?
Is old (outside of guidelines) pavement data retained and reported until it is replaced by new data?
Do all paved sample sections include IRI or PSR, Surface Type, Rutting, Cracking, and Faulting reported? (required, by surface type) If not, is a Plan of Corrective Action in place to correct?
Is the pavement data reported in HPMS consistent with roughness data in the State's pavement management system? If not, why not?
Does the State use one or two technicians to measure roughness (2 is a good safety factor)?
Is pavement data filtered?
Is the average of two wheel paths data reported? (MRI, Mean Roughness Index)
Does the State use one direction for reporting pavement roughness in HPMS? (Example: east to west or south to north)
Does the State use the same direction each time pavement roughness data are collected?
Roughness should not be measured on both directions of roadway for HPMS. If both directions are collected, how are they used for HPMS reporting?
On multi-lane facilities, which lane(s) does the State use to collect roughness data?
Are bridges and railroad crossings included in pavement roughness data reported in HPMS? If not, is a Plan of Corrective Action in place to correct?
Are these conditions followed when measuring pavement roughness?
Does the State collect pavement data for off-state system roadways?
What State or local pavement management systems are there? Describe.
What percent of NHS VMT in the State has an IRI below 95 and below 170 inches per mile?
Do pavement roughness reports list all available information necessary to locate the section using agency's current referencing system?
Are the latest HPMS data collection requirements being met?
How is data transferred from pavement management and locals to the HPMS coordinator for uploading to FHWA?
Is pavement data verified in the field, especially where improvements are made?
Does the State adhere to AASHTO standards for pavement data collection?
Is there a quality assurance plan in place? The plan should include daily quality control equipment procedures (accelerometers & non-contact sensors), a schedule for accuracy checks of roughness equipment, pavement roughness survey personnel training records, and a schedule for the regular calibration of roughness equipment. (Reference Practical Guide for Quality Management of Pavement Condition Data Collection)
The State's sample panel should have been randomly selected from roads in all geographic areas of the State. Both additions and deletions to the sample panel should also have been accomplished through a random selection process. The use of other than random sampling can introduce bias into the sample, and sample bias can adversely affect expanded sample travel estimates and other data applications relying on an expanded sample. With greater reliance on using the expanded sample for calculating travel and performance data, good sample management is an important consideration. The HPMS 8.0 software allows samples to be generated assuring that a random selection is made.
Active management of the sample is necessary to assure that the sample panel continues to represent the universe of public roads, to account for road system changes over time, and to account for the normal growth or decline of traffic volume. Sample management also allows the State to maintain a cost effective sample plan with neither too many nor too few samples.
The sample panel should be checked frequently to determine if there are a sufficient number of sections in each traffic volume group. This can be done using the sample adequacy routine in the HPMS submittal software. Adjustments to the sample should be made when necessary and can be done over time to reduce the reporting burden.
However, even if a State's sample panel is adequate, that does not mean that the sample data are adequate since the new HPMS data model makes each data item independent. The coverage of a sample data item may be measured as a percent of the sample panel that has data. For complete adequacy, the sample panel must be adequate and each sample data item must have 100% coverage.
Sample adequacy should be monitored continually however; an optimal time for more in-depth analysis is in the period immediately following the annual submittal. This permits any sample adjustments to be made in time to meet the next year's reporting date, and allows ample time to accomplish any additional data collection that might be needed for sample additions.
Some of the issues that could be examined include:
Has the State checked their sample adequacy to ensure that the number of samples per volume group meets the sampling requirements? Has the sample been updated when required?
Has the State adjusted the sample to reflect the adjusted urban boundaries? Is the State prepared to incorporate the 2010 census boundaries? Does the State have a plan to revise the sample panel based on these changes?
Are there any problems or issues in meeting sample adequacy requirements? Is the sample panel reviewed and updated on a periodic (3-year maximum) basis?
Are there un-sampled, under-sampled, or oversampled volume groups and what is the plan to address them? Has this plan been presented to the FHWA Division Office and to HPPI-20? Does the State use a random process or the HPMS software, considering all roadway sections both on and of the State system when selecting samples?
There should be at least three samples in each traffic volume group whenever possible. If the traffic volume groups are so small that there are not enough sections to meet the minimum criteria, there should be a review of the traffic data used to assign the sample sections to the traffic volume group to assure that there is a real need for a separate group. If the review shows that a separate small volume group is needed, then all sections should be samples.
Are there volume groups that have expansion factors greater than 100.00? Additional sample sections should be selected from the universe until the expansion factor is reduced to a maximum of 100.
Is there evidence of possible sample bias in the sample panel? This can be determined by looking at a map of sample locations. It is more likely that sample bias may be a problem on the middle functional systems where the State owns fewer of the roads. Areas to review could include:
What remedies are proposed to make up for any existing sample bias?
How does the State assign roadway sections to volume groups when it does not have actual, current traffic count information?
Are structures deleted from the sample where it is possible to do so? The State should eliminate samples that are entirely on a structure unless a volume group sample size requirement cannot be satisfied without including a structure-only section.
What steps has the State taken to identify and reduce the number of too-short sample sections? When a sample section must be split as a result of boundary, functional system, traffic, or other significant roadway characteristic change (see HPMS Field Manual, page 6-12), the State may wish to eliminate the sample and select a new sample if a split would result in a sample section that does not meet the minimum sample length recommendations (see HPMS Field Manual, page 6-7). Length requirements can be waived if those sections are all that are available.
Do sample breaks conform to the criteria in the table on page 6-13 of the HPMS Field Manual?
Does the State have a process for adding new roadway miles to the sample frame in a timely manner?
The HPMS sample is a stratified random sample of physical roadway sections. The data provide through the HPMS relates to physical characteristics and operating conditions on each of the sampled roadway sections.
Samples are stratified as follows:
State – Rural/small urban/urbanized – Roadway functional system – Traffic volume group
All publicly owned roadway sections meeting the stratum criteria are eligible for selection as a sample on a random basis. The determination of the number of samples needed in each traffic volume group (the sampling rate) is based on the traffic volume (AADT) data item because of its high variability compared to other data items in the HPMS.
Samples are expanded based upon the ratio of total roadway miles in a traffic volume group to the total of sampled miles of roadway in that volume group.
The sample is considered a semi-fixed sample panel. Samples are generally fixed over time; however, they may migrate from one traffic volume group to another, usually because of reclassification of one of the stratum criteria. Since traffic volume is a dynamic variable, sections most often move from one traffic volume group to another as a result of AADT growth. Samples also move when there are changes to their rural/urban characteristics as a result of census population changes, and when the functional class changes as land is developed and the traffic function of a roadway changes. Maintaining the sample panel requires the addition (and deletion, as long as adequacy is maintained) of samples over time to account for the shifts of existing sample sections between traffic volume groups.
As a result, active management of the sample panel is necessary to assure that the sample continues to represent the full extent of roads, to account for road system changes over time, and to account for the normal growth in traffic. Sample management also allows the State to maintain a cost effective sample plan with neither too many nor too few samples.
There are a number of practices that should guide all sample management activities:
Since the sample panel is a stratified random sample, sample selections must be made on a random basis from all road sections that meet the stratum criteria. This applies whether new sections are being selected from the full extent for addition to the sample panel, or whether existing sample sections are being selected from a stratum for deletion.
Additional sampling criteria should not be applied when selecting sample sections. For example, the selection of samples should not be limited to State owned road sections only to the exclusion of roads owned by city or county governments.
The sample panel should be checked frequently to determine if there are a sufficient number of sections in each traffic volume group. Adjustments to the sample panel must be made on a random basis.
The best time to check sample adequacy is in the period immediately following the annual submittal. This permits any sample adjustments to be made in time to meet the next year's reporting date, and allows ample time to accomplish any additional data collection that might be needed for sample additions.
The sample also should be checked to assure that there are at least three samples in each traffic volume group whenever possible. If the traffic volume groups are so small that there are not enough sections to meet the minimum criteria, there should be a review of the traffic data used to assign the sample sections to the traffic volume group to assure that there is a real need for a separate group. If the review shows that a separate small volume group is needed, then all sections should be samples.
Generally, existing samples should not be split for reasons other than those reflected in the HPMS Field Manual.
If the expansion factor for a volume group is more than 100, additional sample sections should be selected from the full extent volume group until the expansion factor is reduced to a maximum of 100.
Samples usually become biased when the State violates the random selection rule or imposes other criteria on the sample selection process. Some activities that result in sample bias include:
Selecting only State-owned road sections for sample panel;
Selecting as a sample a section adjacent to an existing sample because it is easier to code the same data;
Selecting as a sample a road section in a specific county or highway district because it is convenient for State staff to access and inventory the section; and,
Applying other external criteria or conditions to the sample selection process that violate the random selection rule.
Existing samples may be biased because the State did not apply a random selection process to the original sample. However, as a result of poor sample management practices, even a sample initially selected on a random basis may become biased if samples are added or deleted on other than a random basis over time.
In general, biased samples are best corrected by randomly selecting an entirely new sample. An alternative the State may consider to remedy past bias is to make any further sample adjustments on a random basis; over time, this should lead to a more unbiased sample. Also, the State may consider making specific adjustments to a sample to eliminate bias directly by adding samples in such a way that the effects of the bias are negated. This last process is somewhat complex in that the bias identification, sample analysis, and sample adjustment must be carried out at the traffic volume group level.
For instance, to determine if a rural major collector traffic volume group is biased to State ownership, it would be necessary to look at the ownership of miles in that particular traffic volume group, both full extent and sample. If the sample reflects the inclusion of both State and non-state owned miles, and the representation in the sample and full extent are reasonably similar, it is likely that the sample was chosen in an unbiased manner.
While this may be obvious if there is a substantial representation of both types of ownership in the sample as well as in the full extent, it may be less than clear where the full extent contains very few miles of either ownership type. A full extent comprised of 90% State owned roads could easily yield a sample containing only State owned roads as a result of random selection. On the basis of probability, a full extent comprised of 80% State owned roads could be expected to have between 1 and 3 non-State owned samples out of every 10 as a result of random selection. The best way to determine bias, however, is to know that the State engaged in a biased, non-random, selection process.
If an adjustment to a sample with a clear State owned road bias is necessary, it only should be made at the volume group level. An appropriate adjustment could consist of randomly adding non-State owned road sections to the sample and randomly deleting the same number of State owned road sections until the number of State and non-State owned road sections had similar representation in both the full extent and sample for that particular traffic volume group. This would keep the total number of samples, and hence the sampling rate, the same. This kind of adjustment should not be done routinely and should be considered only where there is clear evidence that a sample has indeed been biased by the use of improper sampling practices.
A periodic sample management review should be done in cooperation with the State HPMS counterpart. As part of the review of the State's sample management activities, FHWA needs to be able to determine the following:
Does the State annually run the sample adequacy software after the HPMS submittal to determine if an adjustment to the sample plan is needed for the next year's data? To be most effective, this should be done immediately after that data are submitted so as to allow the remainder of the calendar year to be used for making any necessary sample adjustments.
Are adjustments to the sample made on a random basis as a result of the adequacy check?
Are all public roads on the sampled functional systems included in the pool of full extent sections from which new samples are drawn, regardless of ownership?
Is there evidence of sample bias, such as sample clustering on a facility, or within a county, or within a highway district, or is the sample reasonably distributed? This can be determined by looking at a map of sample locations by volume group, functional system and urban/rural area.
Is there sample bias based on State and non-State roads? This comparison needs to be made by volume group within each functional class.
Has the State engaged in practices that can result in sample bias in the past? How and where did it occur? Are biased practices still in use? What changes have been made? It is more likely that sample bias may be a problem on the middle functional systems where the State owns fewer of the roads.
What remedies are proposed to make up for any existing sample bias?
What steps has the State taken to identify and reduce the number of too-short sample sections (short samples are acceptable, only if no other sections are available)?
Are there volume groups that have expansion factors greater than 100?
Has the State adjusted the sample to reflect the latest Census urban boundaries; does the State have a plan to revise the HPMS sample based on these changes?
Does the State have a process for adding new roadway miles to the HPMS full extent in a timely manner?
I the States GIS/LRS ARNOLD Compliant?
Is their GIS data in real or near real time when reflecting the DOT's enterprise data?
Is it a transportation backbone for the entire State, i.e. part of a comprehensive Statewide Geospatial program as recommended by NSGIC?
Is the DOT's GIS section a traditional GIS workgroup bringing in external data to process or is it fully incorporated with the enterprise (relates to question 1).
Does the LRS/GIS match the HPMS data and is it completely current with HPMS, e.g. did it clearthe HPMS validations.
Is the GIS program well-funded e.g. are they fully utilizing SPR?
Is the GIS program growing utilizing new technologies such as 3D LRS, Multi-Level LRS, Geospatial Databases etc.
Is the GIS program vendor neutral, e.g. do they use the best software for the job?
Can the GIS/LRS data be migrated to different platforms easily?
How does the state collect Geospatial Linear data off of the State Highway System? Fed-Aid System (Local Roads)?
Is the DOT executive management aware of the GIS/LRS and the importance to the overall Transportation Community?
Is the GIS fully engaged with the State's GIO (NSGIC representative)? Relates to Q2.
Has the State been made aware of the All public Roads Geospatial Guidance that was recently released (October, 2014)