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  • June 2012

    Iowa Highway 5 / US Highway 65 Freeway Corridor

    Interstate System Designation Summary Report

  • IowaHighway5/USHighway65FreewayCorridorInterstateSystemDesignationSummaryReport

    Page1

    IntroductionAsrequestedbytheDesMoinesAreaMetropolitanPlanningOrganization(MPO),theIowaDepartmentof Transportation (Iowa DOT) has completed several planninglevel needs analyses related to thedesignationofthe IowaHighway5 (IA5)/USHighway65 (US65) freewaycorridor intheDesMoinesmetropolitan area aspartof the federal Interstate system. These analyseshavebeen completed tosatisfyFederalHighwayAdministration(FHWA)requirementsforidentifyinganddocumentingtheneedforpotential improvements tomeetdesign standards for Interstate roadway facilities.This summaryreport documents themethodologies and findings of the planninglevel analyses performed on thesubject corridor between the I35 and I80 system interchanges. Specific analyses and resultsdocumentedinthisreportinclude:

    Geometricanalysisofexistingroadwayconditions; Safetyanalysisofroadwaydeficiencies; Rightofwaygateaccesspoints,alternativegateaccesses,andslowmovingvehicleprovisions; Futuretrafficanalysisoffreewayconditionsandinterchangesinthefreewaycorridor;and Resulting conceptlevel cost estimates to rectify geometric deficiencies, replace signage, and

    providealternativeaccessroads.In addition, this report also generally outlines the federal Interstate facility designation process asdescribed in23CFR470A.111andAppendixAof23U.S.C139(a)(b). Thenextsteps in the InterstatedesignationprocessoftheIA5/US65corridorarealsodiscussedshouldIowaDOTpolicydictatemovingforwardwiththedesignationrequest.RoadwayGeometricAnalysisAsbuiltplans for thepreviously constructed IA5/US65 freeway corridorwere examined to identifyexistingroadwaygeometrythatdidnotmeetminimumAASHTOgeometriccriteriaforfreewayfacilities.TheseplanswerereviewedagainstminimumAASHTO interstate/freewaystandardsanddesignspeedsof70mph.Thefollowinggeometricfactorconditionswereanalyzed:

    Superelevation; VerticalcurveKvalue/stoppingsightdistance; Verticalbridgeclearance; Maximum/minimumverticalgrades; Lane/shoulder/medianwidths; Clearzone/designspeed; Sideslope/endconditions;and Rampterminal/interchangespacing.

    As plans were reviewed, notations and comments were made to identify and record locations ofgeometricdesigndeficiencies. Designdeficiencieswere identified throughcomparisonof theasbuiltplan specifications tominimum AASHTO design standards (A Policy on Design Standards InterstateSystem,2005) for freeway facilities tobeeligible foran Interstatesystemdesignation.Additionally,APolicyonGeometricDesign forHighwaysandStreets,AASHTO,2004and theRoadsideDesignGuide,AASHTO,2006wereconsultedperthePolicyonDesignStandardsInterstateSystemfordetaileddesign

  • IowaHighway5/USHighway65FreewayCorridorInterstateSystemDesignationSummaryReport

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    criteria. Whileurbandesign standards apply to the IA 5/US 65 freeway corridordue to its locationwithin the urban boundary of the DesMoinesmetropolitan area, the existing freeway facility wasconstructed tomeetmore conservative ruraldesign standards formost geometric conditions. RuraldesignstandardsintheIA5/US65corridor(whenpossible)willbemaintainedtopreserveahigherlevelofserviceandcomfortforthetravelingpublic.Thesubsequentgeometricconditionanalysiswillreflectthispreference for rural Interstatedesign standardswithin this corridor, includingmedianwidthandinterchangespacing.Severalsubstandarddesigngeometricconditionswereidentifiedduringthereviewoftheasbuiltplans.Table1summarizestheresultsoftheanalysis,alongwiththecorrespondingAASHTOGreenBook2004referencepagethatdemonstratesthecriteriastandardnotmet.

    Table1:IdentifiedsubstandardgeometricconditionsAssessment

    commentspageAASHTOGreenBook2004page Substandardcondition

    1,2 236 Roadwaybelowminimumgradeof0.3%3 168 Superelevationdoesnotmeet70mph(doesmeet65mph)*4,5 168 Superelevationdoesnotmeet70mph(doesmeet65mph)*6,7,8 236 Roadwaybelowminimumgradeof0.3%

    9,10,11 236 Roadwaybelowminimumgradeof0.3%12,13,14 236 Roadwaybelowminimumgradeof0.3%

    15 168 Superelevationdoesnotmeet70mph(doesmeet65mph)*16 RDG** 30'clearzonerequiredat70mph16 509 Minimum50'medianrequired

    *emaxof6%usedperIowaDesignStandards**AASHTORoadsideDesignGuideAerialphotographywasusedtodeterminethedistancebetween interchanges. Table2 lists locationswhereminimum rural interchange spacing criteriawerenotmet. Severalof these locationshaveanauxiliarylanebetweeninterchangestoimproveweavingconditions.TheselocationsarenotedinTable2.

    Table2:SubstandardinterchangespacingInterchangespacing

    Interchangefromto Spacing* Comments

    I35to35thSt.

  • IowaHighway5/USHighway65FreewayCorridorInterstateSystemDesignationSummaryReport

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    In addition to substandard rural interchange spacing, one locationwith substandard ramp terminalspacingwasidentified.Thatlocation,NEHubbellAvenue(US6)interchange,hasrampterminalspacingoflessthan2,000feetandisthereforeconsidereddeficientperAASHTOGreenBookpreferredcriteria.GeometricdeficienciesintheIA5/US65corridoridentifiedduringtheasbuiltgeometricanalysiswereverifiedby field investigation through theuseofaStabilaSmartLevel,100foot tapemeasure,andadigital camera with GPS capabilities. Additionally, typical cross sections were measured anddocumented at locations deemed representative of each geometric deficiency area. Site conditionswere also noted, including drainage, pavement condition, clear zone obstructions, signage, andemergencyturnaroundpoints. Additionalmeasurementsweretakenattheapproximate locationsoffull superelevation at each deficient location identified in the asbuilt analysis. These notations andobservationshavebeendocumentedinAppendixAtothistechnicalmemorandum.Allroadwaygeometricdeficiencies identifiedthroughtheasbuiltplanreviewwereverifiedduringthefieldinvestigation.However,fieldobservationsofadequatedrainageinfrastructureandclearzonesanda good overall condition of the facility indicate that the identified geometric deficiencies, especiallythose that generate concerns with roadway drainage, do not cause adverse driving or roadwaymaintenance conditions. However, roadway superelevations lacking a 70 mph design speed maynecessitate a lower posted speed limit to enhance safety at those locations. Existing signage onroadside, overhead, and bridgemounted structuresmay need to be replacedwith signagemeetingfederalInterstatesignagestandards,possiblyincludingroadsidemilemarkernumbering.SafetyAnalysisofRoadwayDeficienciesPreviously identifiedgeometricallydeficient locations in the IA5/US65 freewaycorridorwere furtherexamined todetermine if those locationsmaycreateconditions forhighernumbersofcrasheswhencomparedagainst statewideaverages for similar facilities. Crashdatawereobtained from the IowaDOTforthemostrecentfiveyearperiodavailable(20062010).Safety analysis results show that among the seven previously identified locations with geometricdeficiencies along the corridor, three have crash rateshigher than the statewide average for similarroadway facilities. Locations of the geometric deficiencies are displayed on the attachedOverviewMap. Table 3 displays the summarized results of the safety analysis at the seven locations withidentifiedgeometricdeficiencies.

  • IowaHighway5/USHighway65FreewayCorridorInterstateSystemDesignationSummaryReport

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    Table3:Safetyanalysissummaryofgeometricdeficiencies

    Freewaysegment Geometricdeficiency

    Segmentlength(miles)

    Totalcrashes(20062010)

    Crashrate(perHMVMT)

    Statewidecrashrate(per

    HMVMT)

    35thStreet Belowminimumgradeof0.3% 0.55 14 56.5 48

    SWConnector Superdoesnotmeet70mph 1.40 23 37.2 48

    US69 Belowminimumgradeof0.3% 0.88 10 31.9 48

    IA5 Belowminimumgradeof0.3% 0.61 23 192.5 48

    NorthofArmyPostRoad

    Belowminimumgradeof0.3% 0.72 11 41.9 48

    Vandalia Superdoesnotmeet70mph 0.55 21 124.5 48

    I80 Minimum50'medianrequired 0.64 13 45.9 48

    Nearlyallofthecrashesatthethreelocationswithhigherthanstatewideaveragecrashratesaresinglevehicle crashes. This could indicate that theremay be outside factors such as deficient geometrycontributing to the number and type of crashes. Additionally, there were two fatal crashes in thedeficientareasforthe5yearstudyperiod.Duetotheshortlengthandcomparativelylowvolumesofbothoftheseanalysissegments,onefatalcrashina5yearperiodskewsthecalculationshigherthanthestatewidefatalcrashrate.RightofWayGateAccessPointsThe existence of IowaDOT right ofway gate access points is an important issue in the IA 5/US 65freewaycorridordue to the requirements thatan Interstate facilitybe fullyaccesscontrolled.Shouldthe IA5/US65 facilitybedesignatedaspartof the Interstatesystem,all IowaDOT rightofwaygateaccesspointswouldbepermanentlyclosedtomeetthefullaccesscontrolrequirements.Todeterminelikely locations of existing access gates in the IA 5/US 65 corridor, parcelswith common or similarownership that appeared to be split by Iowa DOT right of way were identified using GIS parcelownershipdatafilesfromPolkandWarrencounties.AfieldvisualinspectionoftheIA5/US65corridorwas then completed to visually confirm gate access points. Right of way gate access points werephotographedandloggedtodocumenttheirlocationandcondition.ThefieldinvestigationinitiallyidentifiedfivegateaccesspointsintheIA5/US65freewaycorridor.Oneadditional gate access point was later identified, photographed, and logged during the geometricdeficiency field verification exercise. Three gate access points are located between the US 65/I80systemsinterchangeandtheUS65/US6interchange.TwogateswerelocatedlessthanonemilenorthoftheUS65/UniversityAvenueinterchange,andonegatewasfoundontheIA5corridorwestoftheIA5/US 69 interchange. Approximate locations of the six farm gate locations are displayed on theOverviewMap. Utilitymaintenanceand farmprop

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