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FHWA Functional Classification Guidance Update Presentation – Office of Highway Policy Information (OHPI)


FHWA Functional Classification Guidance Update

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HIS Presentation

Thursday, November 17, 2011
Joseph Hausman, FHWA



  • Federal-Aid Highway Act of 1973 required the use of functional highway classification to update and modify the Federal-aid highway systems
  • First complete guidance document published in 1971
  • Partial update in 1989
  • HPMS 2010+ and some revisions in 2008

Cover for Highway Functional Classification: Concepts, Criteria and Procedures


Current Process

  • Functional Classification and Urban Area Boundaries updated after decennial Census
  • Expectation is for a 3 year process
  • FHWA Division office approves updates
  • Many states share update responsibilities with MPOs


Reasons for Update

  • Federal interest
    • Rational system promotes efficient distribution of capacity and cost-effective use of resources
    • Consistency in treatment from state to state
    • Eligibility for funding
  • Existing guidance dated
    • Does not account for 3C process
    • Decidedly "low-tech" – pre-GIS
  • Guidance leading to more consistent functional classification assignments and urbanized area boundaries needed
  • Create process more states can adhere to


Consistency across states in range


Current Study

  • Update to existing guidance
  • States – Is identification of Other Freeways and Expressways consistent?
  • What’s the difference between Minor Collectors in rural areas and small urban or urbanized areas?
  • How does urban-rural neutrality affect guidance?
  • Is different extent guidance needed?
  • How can GIS be used ?


Existing Guidance

  • Classifications based on the character of service roadways are intended to provide
  • Mobility and land access noted as primary determinants of functional classification

Diagram of Land Access Mobility for each Functional System, and Access (complete, unrestricted, etc.).


Existing Guidance

  • Mileage and VMT stratifications recommended as system validation steps

Diagram of Plotted Cumulative Road Mileage versus Cumulative Vehicle Miles Served, by percent of rural vehicle mile, and rural road miles.

Table II-3 — Guidelines on extent of urban functional systems
System Range
Principal arterial system 40-65 5-10
Principal arterial plus minor arterial street systems 65-80 15-25
Collector StreetSystem 5-10 5-10
Local street system 10-30 65-80


Pros and Cons

  • Functional Classification as foundation of a rational, hierarchical roadway system
  • Criticized as emphasizing speed over livability/community needs

Picture of an hierarchical roadway system

Showing “Do Not Sign� on methodology based on Proportion of Service.


Current Study

  • Task 2 – State of the Practice
    • Literature review
    • Data analysis
    • Interview/survey DOTs/MPOs
  • Task 3 – PA/OFE Review
  • Task 4 – Collector Review
  • Task 5 – AADT Review
  • Task 6 – Adjusted Urban Boundary Concepts
  • Task 7 – Recommendations
  • Task 8 – Final Report


Task 2 – HPMS Data Review

  • How close are states to extent guidance?
  • Is there a significant difference between urban and rural designations/classifications?
  • Is there an obvious correlation between roadway attributes and functional classifications?


Urban vs. Rural

  • Urban VMT exceeds rural VMT in 38 states

Map showing urban VMT exceeding rural VMT in 38 states.


Urban vs. Rural

  • Rural mileage > urban mileage in all but 9 states (including the District of Columbia)

Map of the United States showing th eRural mileage > urban mileage in all but 9 states (including the District of Columbia)


Consistent Patterns

Graph showing Mileage of all rural functional system groupings - percentages by state. For rural functional classifications, we see very consistent distributions of mileage.


Some Existing Guidelines Need Revision

Graph showing mileage of rural principle arterial system percentages by state.


Some Existing Guidelines Need Revision

Mileage Principal Arterial/Other Freeway and Expressways - Percentages by State.


VMT Shows Much Greater Variability than Mileage

Graph showing the VMT of All Urban Functional System Groupings Percentages by State


AADT Ranges Overlap

HPMS Future AADT Ranges by Functional Class - California


VMT Minimum Ranges Overlap

Graph showing HPMS VMT Ranges by Functional Class Illinois


Truck %’s Show Progression by FC

Graph showing Truck Percentage in New Mexico


Task 2 Interview

  • Current practices – process and technical
  • Relevance and utility of functional classification
  • Assignment of specific classifications
  • Suggestions for more efficient procedures

Map of the United States and assignments of specific classifications. North Central Texas Council of Governments, Mid-America Regional Council, Michigan Area Council of Governments. Sought a mix of big/small, urban/rural and mix of states/MPOs.


Urban Area Boundary Adjustments

  • Timeline for last adjustment update
    • Start between fall 2002 to late 2004
    • FHWA approval spring 2003-2005
    • Only one agency required more than 2 years
  • Challenges to on–time completion
    • Large number of urbanized areas
    • Newly created urbanized areas
    • Merging of urbanized areas
    • Lack of staff
    • Managing review and input process


Urban Area Boundary Adjustments

  • Work done mostly in-house
    • Two agencies use outside help
  • What’s challenging?
    • Really expanded boundaries
    • Applying consistent criteria, especially for large states
    • Inconsistent data formats
    • Transferring information from paper to GIS
    • Areas crossing state lines
    • Committing staff to task
    • Local Understanding of UAB use


Urban Area Boundary Adjustments

  • Typical update done via multi-agency committee meetings, with paper maps
  • How different in 2010 (from interviews)?
    • Use of more systematic process based on GIS
    • More paperless
    • Web-based mapping system – common workspace for agencies
    • Send out 2000 adjusted boundaries and 2010 Census boundaries
    • Ignore small urban areas


Functional Classification Updates

  • Timeline for completion of last update
    • In general, much longer process than urban area boundaries (as late as 2010)
  • Mostly done in-house, mostly paper updates
  • Typical Process = FC Maps to MPOs then on to local agencies
  • Data and quality issues typical
    • Missing roads
    • Local assignments – initial lack of consistency with FHWA guidelines
      • MPOs address – sometimes


Functional Classification Updates

  • Process Challenges?
    • Lots of coordination necessary, "back and forth" really time consuming
    • Process gets political
    • Schedule too optimistic
  • Technical Challenges?
    • Conversion from paper to electronic maps difficult
    • Different agencies using different databases


Functional Classification Updates

  • Ongoing updates
    • Process well understood and procedures clear
    • Several states provide procedures/forms
  • 2010?
    • Some unsure – need updated and clearer guidance
    • Some use 2000 process with more GIS
    • Some plan more coordination earlier
    • One DOT – online mapping tool – can complete entire process in 6-8 months
    • Paperless submittal process


Functional Classification Updates

  • Interview participants say they
    • Publish formal evaluation criteria
    • Use FHWA FCs for their own planning needs
    • Use FHWA FCs for statistical reporting (6/9), project prioritization (6/9), access management (5/9), emergency relief funding (5/9)
  • Recommended changes to guidance?
    • Recognize differences in urban areas (e.g., suburban, CBD )
    • Freshen graphics {and provide more examples}
    • Add technical criteria for classification
    • Provide one "suggested procedures" section for all FCs


Task 2 – Literature Review

  • Many states publish guidance on FC/UAB updates – process and criteria
  • Some have schedule for annual requests (e.g., Utah)

Illustration of FC/UAB processes and criteria


State FC/UB Updates – Arizona

  • Written request to MPO with map/data/justification
  • Regional Planning Board considers mileage implications and offset – adopts via resolution or motion
  • ADOT considers impacts on NHS, HPMS, development corridors, STIP, etc.
  • FHWA division considers rationale/justification


State FC Guidance

  • Few states publish formal FC technical guidance
  • Connectivity, traffic characteristics, trip lengths, roadway design, travel generators are factors cited
  • Federal guidance borrowed/cited heavily


State FC Guidance – Wisconsin

County Population Density Basic Criteria – Must Meet Any 2 of the criteria below Supplemental Criteria Desirable Mileage % of System Range
Land Use
Spacing Current ADT
<43 Connect places:
1,000 – 4,999 to >50,000
5,000 – 49,999 to 5,000 – 49,999
1,000 – 4,999 to >50,000
1,000 – 4,999 to 5,000 – 49,999
or to principal arterials
Serve all traffic generating activities with an annual visitation of >300,000, if not served by a principal arterial. Maximum 30 miles between Arterials >1,000
  1. Alternate population connection
  2. Major river crossing – restrictive topography
4.0% – 8.0% statewide
> 43 > 2,000


State FC Guidance – Iowa

Chart showing Rural and Urban Federal Functional Classification by Interstate, OPA, Minor Arterial, Major Collector, Minor Collector, and Local.


Evolution of State FC Guidance

  • Traditionally strong linkage between FC and design
  • Some states introducing flexibility based on context/multimodal needs
  • Montana – multimodal street classification
  • Idaho – conform to surrounding environment
Functional Street Classification for Boulevard, Avenue, Street, by functional System, for Urban, Suburban, Transit, and Industrial.


Urban Area Guidance – Oregon

  • Encompass entire UA, and use urban cluster or urban place boundaries as minimum
  • Create continuous line, can include municipalities nearby and urban growth boundary
  • Include traffic generators, terminals, boundary streets, rapidly developing areas


Task 3 – PA/OFE Review

  • No significant difference between rural and urban PA-OFE
    • Designation conforms to surrounding area
  • Little impact on decision-making
  • Should eliminating or clarifying distinction be considered?
  • If retain distinction, perhaps refer to levels of access control


Task 4 – Major vs. Minor Collector Review

  • Designation linked to likelihood of funding
  • Little consistency in designation across states
  • Distinction does not appear to be strongly warranted based on use, design, etc.
  • Distinction between Major and Minor should be clarified


Task 5 – AADT

  • States refer to AADT and VMT ranges
  • Most states do adjust FC distributions when they deviate
  • Data suggests VMT guidance is much less relevant
  • Urban Collector maximum of 10% no longer applicable
  • Agencies not adjusting based on traffic forecasts


Potential New Guidance Features

  • Different recommendations/procedures for different areas
    • Built-out (infill)
    • Developing (raw land)
  • Describe how to use GIS in classification and boundary work
    • Measure access to population and activity centers
    • Measure linkage between urban areas and activity centers
    • Integral for procedures to smooth urban area boundaries
    • Use for analyzing change in demand over time


Potential New Guidance Features

  • Clarify how to apply mileage/VMT guidelines
  • Incentivize use of paperless process
  • Focus on roads that need change in FC
  • Recognize bottoms-up process
    • Develop document for local partners, not just states


Page last modified on November 7, 2014.
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