Table Of Content1
Joint
Transportation
Research
Program
JTRP
FHWA/IN/JTRP-98/12
Final Report
ASSESSING AND UPDATWG INDOT'S TRAFFIC
MONITORING SYSTEM FOR HIGHWAYS
VOLUME MAINREPORT
I:
Samuel Labi
Jon D. Fricker
September 1998
Indiana
Department
of Transportation
Purdue
University
FINAL REPORT
(Volume 1: Main Report)
ASSESSING AND UPDATING
INDOT'S TRAFFIC MONITORING SYSTEM FOR HIGHWAYS
FHWA/IN/JTRP-98/12
by
Samuel Labi
Research Assistant
Jon D. Fricker
Professor
Purdue University
School ofCivil Engineering
Joint Transportation Research Program
Project No.: C-36-64K
File No.: 3-5-1 l,HPR-0438
Prepared in Cooperation with the
Indiana Department ofTransportation and
The U.S. Department ofTransportation
Federal Highway Administration
The contents of this report reflect the views of the authors who are responsible for the
facts and the accuracy of the data presented herein. The contents do not necessarily
reflect the official views of the Federal Highway Administration and the Indiana
Department ofTransportation. This report does not constitute a standard, a specification,
or a regulation.
Purdue University
West Lafayette, Indiana47907
September 30, 1998
Digitized by the Internet Arciiive
in 2011 with funding from
LYRASIS members and Sloan Foundation; Indiana Department of Transportation
http://www.archive.org/details/assessingupdatinOOIabi
ACKNOWLEDGMENTS
The authors wish to acknowledge the assistance provided by Don Houterloot,
John Nagle, Henry Rhee, Mohammed Shaikh, all of INDOT Roadway
Management Division. Thanks are also extended to other INDOT staff such as
Steve Smith, Marcia Gustafson, Geraldine Lampley, Leah Snow and Cordelia
Jones-Hill. Persons responsible for the development of the various management
systems such as Robert Woods, John Weaver, and Kirk Mangold provided
valuable information for this study.
The contributions ofthe Metropolitan Planning Organizations (MPOs) in the State
of Indiana, as well as several states' DOTs, whose personnel responded to our
questions and questionnaires, are gratefully acknowledged. Professor Kuczek of
the Statistics Department of Purdue University also provided useful help
regarding the statistical aspects of the study. The comments and contributions of
Larry Heil, Lisa Gion, and Don Johnson of the FHWA were useful through out
the course ofthis study.
Finally, we are grateful for the financial support and research opportunity
provided by the Indiana Department of Transportation and Purdue University
through the Joint Transportation Research Program (JTRP).
111
TECHNICALREPORTSTANDARDTITLEPAGE
1. ReportNo. 2. GovernmentAccessionNo. 3.Recipient'sCatalogNo.
FHWA/IN/JTRP-98/12
4.TitleandSubUtle S. ReportDate
September 1998
AssessingandUpdatingINDOT'sTrafficMonitomingSystemforHighways(2 Volumes)
6. PerformingOrganizationCode
7.Author(s) 8. PerformingOrganization ReportNo.
S. LabiandJ.Fricker
FHWA/IN/JTRP-98/12
9. PerformingOrganizationNameandAddress 10.WorkUnitNo.
JointTransportationResearchProgram
1284 CivilEngineeringBuilding
PurdueUniversity
WestUfayette,Indiana 47907-1284
11. ContractorGrantNo.
HPR-0438
12. SponsoringAgencyNameandAddress 13. TypeofReportandPeriodCovered
IndianaDepartmentofTransportation
StateOfficeBuilding FinalReport
100NorthSenateAvenue
Indianapolis,IN46204
14. SponsoringAgencyCode
15. SupplementaryNotes
PreparedincooperationwiththeIndianaDepartmentofTransportation andFederalHighwayAdministration.
16. Abstract
ThisstudyevaluatestheexistingresourcesandproceduresofINDOT'scurrenttrafficmonitoringprogram,withtheobjectiveoftransforming
thisprogramintoacomprehensiveTrafficMonitoringSystem forHighways(TMS/H).Reliabletrafficdataisavaluableinputforstudiesand
decision-makingatvariouslevelsandin variousphasesofhighwaymanagementincludingplanninganddesign,financeandtaxation,
legislationand safety. ThenatureandscopeofthevariouscomponentscomprisingaTMS/Hforanystatewereidentifiedinavailableliterature
suchastheFederal Registerand TrafficMonitoringGuide.
Acompleteinventoryoftheexistingresources(personnelandequipment)andproceduresused forfielddatacollectionandoffice-baseddata
processingwerecompiledand evaluated foradequacyand/oraccuracyandappropriatenessbymatchingthemwithrequirementsstatedin
availableliteraturetoensurecompliancewithISTEArecommendations.
Ingeneral,theexistingtrafficmonitoringprogramwasfoundtobeadequateinmeetingtheneedsofmostmanagementsystems,withthe
exception ofvehicleclassification monitoringatsectionshaving 'abnormal' trafficconditions. FortheContinuousCountprogram,alarge
numberofadditionalclassificationATRstationsarerecommendedwhileveryfewadditionalWIMsitesareneeded.AllHPMS samplesections
andNHSsegmentsarecoveredundertheexistingprogram,althoughalackofresourcessometimeslimitsthefrequencyofdatacollection.
Also,anewscheduleforcoveragecountsisproposedtoplacegreateremphasisonNHS roadsand high-growthareasofthestate.Anew
databasesystem isrecommendedtoeffectivelyaddressdatamanagementissues.Also,documentationoffieldoperationsandofficefactoring
procedureswascarriedoutinthisstudy.
With therecommendationsfrom thisstudy,INDOTintendstostreamlineitsoveralldatacollectionactivitiesandtoimprovetheaccuracy,
adequacy,timeliness,anddeliveryofdatatotheend-users.
17. Keywords 18. DistributionStatement
Trafficmonitoring,managementsystems,highwayperformance Norestrictions. Thisdocumentisavailabletothepublicthroughthe
monitoringsystem,continuouscounts,coveragecounts,national National TechnicalInfonnation Service, Spnngfield,VA22161
highwaysystem,vehicleoccupancy,databasesystem,adjustment
factors.
19. SecurityClassif.(ofthisreport) 20. SecurityClassif.(orthispage) 21.No.ofPages 22. Price
Unclassified Unclassified 542
FormDOTF1700.7(8-69)
IV
EXECUTIVE SUMMARY
The Intermodal Surface Transportation Efficiency Act of 1991 (ISTEA) established a
new emphasis in transportation system policy in the United States. This legislation
mandated, among other requirements, the development and implementation of a Traffic
Monitoring System for Highways (TMS) in each state. The Federal Register of
December 1993 defines a TMS as a systematic process for the collection, analysis,
summary and retention of roadway related person and vehicular data, including public
transportation on public highways and streets. This study did not establish an entirely
new TMS for the State of Indiana, but rather involved validation of existing procedures
and resources, and recommendations for improving INDOT's current traffic monitoring
program to a traffic monitoring system. Cost estimates have been provided for all
recommendations that have been made. With the recommendations from this study,
INDOT intends to streamline its overall data collection activities and to improve the
accuracy, adequacy and timeliness of data collection, processing and analysis. The main
references used in this study were the HPMS Field Manual, FHWA's Traffic Monitoring
Guide, the AASHTO Guidelines for Traffic Data Programs, and Subpart H (Traffic
Monitoring System for Highways) of the Federal Register dated 1 December 1993.
Based on the components of a TMS required by ISTEA, the following areas were
addressed:
The Management Systems- Generally, the existing traffic monitoring system is adequate
to meet the needs of most management systems. The only significant shortcoming that
needs to be addressed is monitoring of vehicle classification at high-speed, low-speed,
and congested sections. For this, the use of "non-intrusive" technologies such as video
and radar, have been recommended in this report. The ISTEA requirement for the
Management Systems was later scaled back by subsequent legislation, but INDOT, like
most other states' DOTs, are continuing with the development and implementation of
management systems to fulfill state needs.
Continuous Counts (ATRs)- The best criterion for grouping ATR sites, and the number of
additional ATRs required and their appropriate locations, for each count type, were
determined: For traffic volumes, the existing INDOT grouping, which considers the area
and functional classes ofthe ATRs, was chosen. The existing 92 traffic volume ATR sites
were found to be adequate. The current seasonal factors used to annualize short-term
volume data, derived using the existing INDOT group list, are therefore appropriate. A
combination of regional and functional classes was found to address state-wide vehicle
classification ATR data in the best manner. A large number of additional classification
sites are needed. Upgrading of the existing volume-counting ATRs and speed monitoring
sites to classification-monitoring capabilities before establishing completely new vehicle
classification ATR sites is recommended. For truck weights, the criterion based only on
functional classes was selected, and this calls for a small number of additional truck-
weighing ATR sites to supplement the current number ofWIM stations
.
Coverage Counts- The number of short-term coverage counts for the Highway
Performance Monitoring System (HPMS) and the County Flow Map (CFM) system, over
a three-year cycle, were assessed for their adequacy. Also, the accuracy and adequacy of
equipment used for this activity were evaluated.
The existing volume and classification coverage activities cover all HPMS sample
sections although a lack of resources sometimes limits the frequency at which data is
collected. The HPMS truck weighing subprogram is currently in an experimental stage,
and a life-cycle cost analysis framework has been devised for determining the optimum
equipment use for this activity, in the event that weight data becomes a reporting
requirement for HPMS. Based on revised frequencies for coverage (CFM) counts on
roads on the National Highway System (NHS) as well as roads in high growth counties, a
new schedule for coverage (CFM) counts has been proposed, and additional resources
needed to implement the new schedule have been determined. Documentation of field
operations relating to equipment accuracy and testing has been carried out in this study,
and recommendations have also been made to improve certain aspects of these field
operations.
Vehicle Classification on Segments of the National Highway System (NHS)- Currently,
INDOT has no specific program to monitor classification on segments on the NHS.
Rather, use is made of other count programs (i.e., ATR and coverage counts) at sites that
overlap with the NHS network. An evaluation of such monitoring activities on the NHS
network revealed that classification on most NHS segments is carried out by at least one
count program, albeit over a 5-year cycle. The current cycle duration for vehicle
classification on NHS segments will be reduced to the required maximum of3 years after
the recommendations for coverage count frequencies and upgrading of existing volume-
counting ATRs, are implemented. The few NHS segments that could not be monitored
even over the current five-year cycle have problems relating to traffic flow: The very fast
nature of traffic at such segments precludes the performance of reliable classification or
volume counts by the usual equipment used for such counts. Such segments should be
monitored using improved sensor technologies or "non-intrusive" technology for a
minimum duration and frequency required for classification activities on the NHS.
Database System- The large volume of data that is expected to be generated after
implementing the recommendations of this study means that an appropriate database
system that would effectively address all stages of data management is needed. Current
methods of managing data are inadequate and need to be upgraded with a database
system. Additional hardware has been recommended to improve the existing network
architecture, while new software systems for data management, i.e., TRADAS and GIS,
have been suggested. Two additional staff are needed to manage these software systems.
Appropriate storage media and data retention lengths for data from the various count
programs have also been addressed.
Office Factoring and Field Procedures- Current INDOT procedures for data
summarization, reporting, and calculation of adjustment factors such as the Seasonal
Adjustment Factor, the Growth Factor, and the Axle Correction Factor, have been studied
and documented in this study. The existing procedures for field measurements and data
