creating a highway information system for safety roadway
TRANSCRIPT
Research Report KTC-15-25/OHS K9-15-04-1F DOI: http://dx.doi.org/10.13023/KTC.RR.2015.25
Creating a Highway Information System for Safety Roadway Features
Our Mission
We provide services to the transportation community through research, technology transfer and education. We create and participate in partnerships to
promote safe and effective transportation systems.
© 2015 University of Kentucky, Kentucky Transportation Center Information may not be used, reproduced, or republished without our written consent.
Kentucky Transportation Center 176 Oliver H. Raymond Building
Lexington, KY 40506-0281 (859) 257-4513 fax (859) 257-1815
www.ktc.uky.edu
Research Report KTC-15-25/OHS K9-15-04-1F
Creating a Highway Information System for Safety Roadway Features
by
Brian Howell, PE, PMP Research Engineer
Ken Agent, PE, MSCE
Research Engineer
and
Eric Green, PE, MSCE, GISP Research Engineer
Kentucky Transportation Center College of Engineering University of Kentucky Lexington, Kentucky
in cooperation with Kentucky Transportation Cabinet
Commonwealth of Kentucky
The contents of this report reflect the views of the authors, who are responsible for the facts and accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of the University of Kentucky, the Kentucky Transportation Center, the Kentucky Transportation Cabinet, the United States Department of Transportation, or the Federal Highway Administration. This report does not constitute a standard, specification, or regulation. The inclusion of manufacturer names or trade names is for identification purposes and should not be considered an endorsement.
December 2015
1.ReportNo.KTC-15-25/OHSK9-15-04-1F
2.GovernmentAccessionNo.
3.Recipient’sCatalogNo
4.TitleandSubtitleCreatingaHighwayInformationSystemforSafetyRoadwayFeatures
5.ReportDateDecember2015
6.PerformingOrganizationCode
7.Author(s):BrianHowell,PE,PMP;KenAgent,PE,MSCE;andEricGreen,PE,
MSCE
8.PerformingOrganizationReportNo.
KTC-15-25/OHSK9-15-04-1F
9.PerformingOrganizationNameandAddressKentuckyTransportationCenter
CollegeofEngineering
UniversityofKentucky
Lexington,Kentucky40506-0281
10.WorkUnitNo.(TRAIS)
11.ContractorGrantNo.
12.SponsoringAgencyNameandAddressKentuckyTransportationCabinet
200MeroStreet
Frankfort,Kentucky40622
13.TypeofReportandPeriodCovered
FinalYear
14.SponsoringAgencyCode
15.SupplementaryNotes
16.AbstractRoadway departures are the leading cause of roadside fatalities. The Kentucky Transportation Cabinet (KYTC) has undertaken a number of roadside safety measures to reduce roadway departures. Specifically, KYTC has installed several low-cost, systemic roadway safety treatments to Kentucky’s roadways in recent years. These treatments include cable barriers, high friction surface treatments, rumble stripes, and Safety Edges. KYTC has installed approximately 44 cable barrier systems over 265 miles of roadway,112 HFST applications over 20 miles of roadway, 750 rumble stripe installations over 2,500 miles of roadway, and 147 Safety Edge treatments on 580 miles of roadway. The project team developed a complete inventory for safety measure installations, including their locations and select characteristics. This information was collected through interviews, KYTC databases, KYTC contract proposals, KTC studies, and onsite assessments. These data served as inputs into KYTC’s statewide highway model. ArcMap was used to reference locations of the inventoried safety treatments. All safety measure installations were compiled into a comprehensive Excel database. The database is a tool that will allow policy makers and transportation agencies to evaluate the effectiveness, cost, and benefits of roadway safety treatments.
17.KeyWordsRumblestripe,rumblestrip,cablebarrier,highfrictionsurface
treatment,HFST,SafetyEdge,roadwaysafetymeasures
18.DistributionStatementUnlimited,withapprovaloftheKentucky
TransportationCabinet
19.SecurityClassification(report)Unclassified
20.SecurityClassification(thispage)Unclassified
21.No.ofPages30
22.Price
iii
TableofContents
ListofFigures............................................................................................................................................................iv
ListofTables..............................................................................................................................................................iv
Acknowledgements..................................................................................................................................................v
ExecutiveSummary.................................................................................................................................................1
Chapter1:Background...........................................................................................................................................3
1.1Introduction....................................................................................................................................................3
1.2ProblemStatement......................................................................................................................................3
1.3Objectives.........................................................................................................................................................3
Chapter2:CableBarrier........................................................................................................................................4
2.1Introduction....................................................................................................................................................4
2.2CompositionandFunction.......................................................................................................................4
2.3Inventory..........................................................................................................................................................5
Chapter3:HighFrictionSurfaceTreatment................................................................................................7
3.1Introduction....................................................................................................................................................7
3.2CompositionandFunction.......................................................................................................................7
3.3Inventory..........................................................................................................................................................8
Chapter4:RumbleStripes.................................................................................................................................10
4.1Introduction.................................................................................................................................................10
4.2CompositionandFunction....................................................................................................................10
4.3Inventory.......................................................................................................................................................12
Chapter5:SafetyEdge.........................................................................................................................................15
5.1Introduction.................................................................................................................................................15
5.2CompositionandFunction....................................................................................................................15
5.3Inventory.......................................................................................................................................................17
Conclusion.................................................................................................................................................................19
AppendixA...............................................................................................................................................................20
References................................................................................................................................................................24
iv
ListofFigures
Figure1:FourStrand,CableMedianBarrier................................................................................................4Figure2:HFSTatU.S.68Curve,MercerCounty.........................................................................................7Figure3:HFSTAggregate.....................................................................................................................................8Figure4:CenterlineRumbleStripes.............................................................................................................11Figure5:EdgelineRumbleStripes.................................................................................................................11Figure6:CenterlineRumbleStrip,SepiaSheet010...............................................................................14Figure7:ShoulderRumbleStrips,SepiaSheet011...............................................................................14Figure8:SafetyEdgeAngle...............................................................................................................................15Figure9:PavementwithSafetyEdge...........................................................................................................16Figure10:PavementwithoutSafetyEdge..................................................................................................16Figure11:CableBarriers...................................................................................................................................20Figure12:HighFrictionSurfaceTreatments............................................................................................21Figure13:RumbleStripes.................................................................................................................................22Figure14:SafetyEdges.......................................................................................................................................23
ListofTablesTable1:RumbleStripeInstalls,KTC-10-01...............................................................................................13
v
Acknowledgements
Thefollowingindividualscontributedgreatlytothesuccessfulcompletionofthisprojectthroughtheir
participationontheStudyAdvisoryCommittee:
KevinMartin…………………………………..…………………….………..........................KYTCDivisionofHighwayDesign
TracyLovell…………………………………..…………………….……….........................KYTCDivisionofTrafficOperations
TimScully…………………………………………………………………......………………………..KentuckyTransportationCenter
MeganWhite…………………………………………….............………………………….…….KentuckyTransportationCenter
NathanielSwallom……………………………………………………..…………………………..KentuckyTransportationCenter
1
ExecutiveSummary
Roadwaydeparturesare the leadingcauseof roadside fatalities.TheKentuckyTransportationCabinet
(KYTC) has implemented a number of roadway safety measures to reduce roadway departures.
Specifically,KYTChasinstalledsafetytreatmentssuchascablebarriers,highfrictionsurfacetreatments,
rumble stripes, and safety edges. For this project, Kentucky Transportation Center (KTC) researchers
developedacomplete inventory foreachof thesesafetytreatmentsby identifyingtheir locationsand
documentingselectcharacteristics.
Cablebarriersarelongitudinalsafetybarrierscomposedofhigh-tensioned,steelcablesconnectedbya
seriesofpostsdrivenintotheground.Theyareprimarilyusedtopreventerrantvehiclesfromcrossing
overintoopposinglanesoftraffic.Researchhasproventheyareeffectiveinreducingcrossovermedian
crashesandassociated fatalities.KYTChas installed44cablebarrier systemsalongapproximately265
miles of Kentucky’s highways since 2007. KTC researchers located cable barrier installations through
coordinationwithKYTC’sOfficeofHighwayDesign.
Highfrictionsurfacetreatments(HFSTs)arethin,highfrictionoverlaysthatconsistofsmallaggregates
held together by a binding agent. A HFST increases surface friction for a vehicle’s tires and prevents
skidding. Research demonstrates that HFST installations reduce crashes. They are most commonly
applied to horizontal curves, interstate ramps, and approaches to stop-condition intersections. Since
2009,KYTChasinstalled112HFSTapplicationsatop20milesofroadway.KTCcollectedHSFTdatawith
the aid of KYTC’s Division of Traffic Operations. KTC also conducted onsite inspections for each
applicationtoverifyitspresenceandtoobtainselectcharacteristics.
Rumblestripesconsistofaseriesof indentationsalongtheroadwaysurfaceoverlainwithapavement
markingtomarkthelaneboundary.Whenvehicletiresdriveoverrumblestripes,adistinctsoundand
vibratory sensation are produced. This alerts the errant driver to move back into the travel lane.
Numerousresearchstudieshaveshownrumblestripesandtheircloselyrelatedrumblestrips(rumbles
installedwithoutpavementmarkings, typicallyon theshoulder) caneffectively reduce lanedeparture
crashes. KYTC has installed rumble stripes at over 750 locations along 2,500miles of roadway since
2008. KTC researchers obtained inventory locations for rumble stripes through previous KTC studies,
KYTCinterviews,andKYTCcontractproposals;theyverifiedthoselocationsthroughoutthestate.
TheSafetyEdgetreatmentreducestheslopeangleatthepavement’sedge,allowingerrantdriverswho
are leaving the pavement the chance to safely correct their course. This feature creates a 30 degree
angle relative to the existing ground surface and eliminates vertical drop-offs often associated with
roadway departures. A Safety Edge reduces incidents related to “tire scrubbing” whereby the driver
tendstooversteerandcrash.KYTChasinstalled147SafetyEdgetreatmentsalong580mileswithinthe
state.KTCidentifiedSafetyEdgelocationsthroughacomprehensivesearchofKYTCprojectproposals.
Multipleresearchstudiesacrossthenationhavedemonstratedthebenefitsassociatedwiththesesafety
measures; the largestbenefit is a reduction in fatalities.Data taken from interviews,KYTCdatabases,
KYTCcontractproposals,KTCstudies,andonsiteservedasinputsintoKYTC’sstatewidehighwaymodel.
ArcMapwasusedtoreferencelocationsoftheinventoriedsafetytreatmentsbeforeallsafetymeasure
installations were compiled into a comprehensive Excel database. Until now, KYTC lacked a spatially
explicit statewide inventoryof thesesafetymeasures.KYTCcouldnot track their locationsormonitor
safety outcomes to quantify their benefits and/or costs to Kentucky. This project addressed those
2
concernsbydevelopingacomprehensive, spatially-explicit inventoryof selectedsafetymeasures.The
databasewillallowpolicymakersandtransportationagencies toevaluate theeffectiveness,cost,and
benefitsofroadwaysafetytreatments.
3
Chapter1:Background1.1Introduction
RoadwaydeparturesaretheleadingcauseofvehiclefatalitiesintheUnitedStates.Infact,theFederal
HighwayAdministration (FHWA)concluded roadwaydepartureswere thecauseof18,257 fatalities in
2013alone.1TheFHWAdefinesaroadwaydepartureasaninstancewhenavehiclecrossestheedgeline
orcenterline,orotherwiseleavesthetraveledway.Thetraveledwayrepresentstheportionoftheroad
intended for driving on between the centerline and edgeline. State departments of transportation
(DOTs) and various transportation professionals have sought solutions to reduce roadway departure
fatalitiesandhavedevelopedseveralroadwaysafetytreatmentstoreduceerrantdepartures.Anumber
of safety treatments have demonstrated utility in reducing the number of roadway departures and
associatedfatalitiesalongU.S.highways.
1.2ProblemStatement
The Kentucky Transportation Cabinet has installed several types of roadway safety measures to
Kentucky’s roads in recent years. These safety measures includemedian cable barriers, high friction
surface treatments, centerline and edgeline rumble stripes, and safety edges. Various transportation
studies have examined and touted the safety benefits derived from these measures. Unfortunately,
KYTClacksacomprehensiveinventorylistingthelocationsfortheseinstalledsafetytreatmentmeasures
acrossthestate.KYTCneededasystemtobettertracksafetymeasurelocationsandassesstheiroverall
performance.
1.3Objectives
Thisstudydevelopedacomprehensiveinventoryforthefollowingsafetymeasures:
a. CableBarriers
b. HighFrictionSurfaceTreatments
c. RumbleStripes(CenterlineandEdgeline)
d. SafetyEdges
4
Chapter2:CableBarrier2.1IntroductionCablebarriersarelongitudinalsafetybarrierscomposedofhigh-tensioned,steelcablesconnectedbya
seriesofposts.2Intheirroleassafetybarriers,theymaybeplacedparallelandalongsidetheouteredge
of the roadway (i.e., just off the shoulder) or longitudinally inside themedian. In the former, a cable
barrierservestoredirectanerrantvehiclebackontotheroad’stravelledwayif itmovesofftheouter
edgeoftheroad.Forthe latter, themediancablebarrierprovidesforthesamepurposebutwiththe
addedbenefitofpreventing crossover lane crashes.According to theFederalHighwayAdministration
(FHWA),“mediancrossovercrashestendtobesevere”andmanystatedepartmentsoftransportation
that installedmedian cable barriers have reported a “decrease in cross-median crash fatalities of 90
percentormore”.3
2.2CompositionandFunction
Cablebarriers typically employeither threeor four steel cables—also knownas strands—that stretch
across attached posts. Each steel post is embedded within the ground to provide structural support
throughloadtransfertothefoundations.RecentcrashtestsperformedbytheNationalCrashAnalysis
Centerhavefoundthatfourstrandsprovidedgreatercontainmentforalargerswathofvehiclesizes.2A
typicalfourstrandcablemedianbarrierisshowninthefigurebelow.
Figure1:FourStrand,CableMedianBarrier
Source:FederalHighwayAdministration4
Cablebarriersfunctionbyabsorbingmuchoftheenergyfromavehicularimpactcrash.Thestrandswill
deflectwhilenearbypostssnapfromtheirembeddedfoundationalsleeves.5Theseactionspreventthe
vehiclefromstoppingsuddenly,whichcanincreasepotentialharmtothedriver.
5
2.3Inventory
TheKentuckyTransportationCabinet(KYTC)hasdevelopedtheirowncablebarrierprogramasameans
to increase highway safety. Since 2007, the Cabinet has installed 44 separate cable barrier systems
throughoutthestate.Forthepurposeofthisinventory,aninstallationisdefinedasasinglecablebarrier
systeminstalledalongarouteinKentuckywithauniquebeginningandendingmilepoint.Someroutes
and/orprojectcontractsmaycontainmorethanone installation. In total,KYTChas installedover265
milesofcablebarrieralongitshighways.Thisprojectcapturedthelocationsandvariouscharacteristics
associatedwitheachcablebarrier installationandconsolidated thedata intoasingle, comprehensive
database.
KentuckyTransportationCenter(KTC)researcherscoordinatedeffortswiththeKentuckyTransportation
Cabinettocollectcablebarrierdata.Specifically,KTCrequestedandobtainedsourcedatafromKYTC’s
Division of Highway Design, Developmental Branch. This division is responsible for the delivery and
lettingofhighwayprojectsandinthisrole,maintainsvisibilityoncablebarrierinstallations.Theprimary
point of contact for this data request was the Transportation Engineering Branch Manager for the
DevelopmentalBranch(phone:502-564-3280).
KYTC provided KTC a spreadsheet dataset that displayed all installed cable barriers from2007 to the
present.Thisspreadsheetincludedthefollowingcategories:
• Itemnumber/contractID
• Dateofletting
• Dateofinstallationcompletion
• Route
• County
• Beginningandendingmilepoints
• Totalmiles
• Vendor
• Contractor
• Cost
KTC collected and sorted cable barrier attributes into a separate spreadsheet database. The KTC
databaseconsistedofthefollowingcategoriesthatweredeemednecessaryforafocusonsafety:
• Identificationnumber
• Districtnumber
• County
• Route
• Beginningandendingmilepoints
• Lengthofcablebarrier
• Directionoftravel
• Dateofinstallation(month,year)
Next, cable barrier installations were incorporated into the GIS-based ArcMap platform. KYTC uses
ArcMapastheirGIS-basedplatformtocollectanddisplaylocationsandattributesfortheiroverallstate
6
highway network. KYTC’s ArcMap relies upon its Highway Information System (HIS) database to
populate road locations, their characteristics, and other related transportation factors. Multiple
divisionswithinKYTCcollect thisdataandprovide it to theDivisionofPlanning for incorporation into
theirArcMapstatewide transportationnetwork.Furthermore,KYTCmaintainscenterlines forallof its
roadwayswhichisusedasalinearreferencesystemforroute-baseddata.Centerlinedataprovidesthe
basis for determining locations for all roads in Kentucky and the dataset is referred to as “All Roads
Measured”.6 Using ArcMap, the cable locations were geo-referenced using the starting and ending
milepointsofthecablebarrierinstallation.
TheoriginalcablebarrierdatareceivedfromKYTCoftenidentifiedlengthycablebarriersacrossmultiple
countyboundaries.Intheseinstances,theKYTCdatalistedeachcablebarrierprojectasasingle,distinct
projectwithmultiplebeginningandendingmilepoints.Itdidnotdifferentiateacablebarrierinstallation
by county. This became problematic when trying to geo-reference the data. To compensate, KTC
researchersutilizedtheonlineKYTCActiveHighwayPlanGISmapasatooltodeterminethebeginning
andendingmilepointsforeachcablebarrierprojectineachcounty.7Researchersidentifiedthelocation
for each cable barrier project and determined the associated milepoints for the cable barrier as it
crossedfromonecountytothenext.Subsequently,beginningandendingmilepointswereassignedto
cablebarriersbycountyandincorporatedintoArcMap.Allofthecablebarrierinstallationsareshownin
AppendixA,Figure11.
7
Chapter3:HighFrictionSurfaceTreatment3.1Introduction
Highfrictionsurfacetreatment(HFST)isathin,highfrictionoverlayconsistingofsmallaggregatesheld
togetherbyabindingagent.Thistreatmentincreasestheroughnessorfrictionattheroadwaysurface
and helps reduce vehicle skidding onwet-roads or onworn pavement. Although the technology has
existedformanyyears,HFSTapplicationshaveenjoyedaresurgenceinpopularityasstateDOT’shave
attempted to reduce highway crashes, most notably, highway fatalities. According to the Federal
HighwayAdministration(FHWA),intersectionsandhorizontalcurvelocationsaccountfornearlyhalfof
all vehicular fatalities.8,9
Recent cases studies, including the Kentucky Transportation Cabinet, lend
support to HFST as an effective treatment to reduce highway fatalities at these locations.10
Consequently,KYTChasinstalledHFSTatseveralhigh-risklocationswithinthestate,includingaU.S.68
curveinMercerCounty(Figure2).Inthisfigure,theHFSTlayerbeginsnearthestartofthecurveandis
shownasadarkershadeofgraythantheprecedingroadwaysurface.
Figure2:HFSTatU.S.68Curve,MercerCounty
Source:KentuckyTransportationCenter11
3.2CompositionandFunction
HFST consists of high friction, abrasion-resistant aggregates bound together by a resin or polymer
binder. This treatment measure is less prone to wear over time, thus contributing to its ability to
maintain high friction surface. Higher surface friction between the vehicle and the roadway surface
provides greater ability to overcome the elevated friction demands inherent at intersections and
horizontalcurvesandtherebyreducestheratesatwhichvehiclesleavetheirintendedpath.
8
HFSTisappliedoverthetopofanexistingroadwaysurfaceandformsabondsothatitremainsinplace.
HFSTmaybeappliedeithermechanicallyormanually.Intheformer,amechanicalspreadercompletes
thethinoverlayprocess.Inthelatter,smallsectionsrequiringHFSTmayonlyrequireroadwayworkers
tousesqueegeestoevenlyspreadthecoatingwhilesweepingawaytheexcess.HFSTmustbeapplied
overastructurallysound,existingroadwaysurfaceandtypically lastsupto10years.12 InFigure4,the
HFSTaggregateisshowninaclose-up,detailedview.
Figure3:HFSTAggregate
Source:FederalHighwayAdministration13
HFST applications help reduce crashes in both types of locations by providing higher friction capacity
thanonstandardroadways.14
3.3Inventory
TheKentuckyTransportationCabinet(KYTC)recentlyadoptedtheuseofHFSTapplicationsasatool in
improvinghighwaysafetyacross thecommonwealth. In thiseffort, theCabinethas installed112high
friction surface treatment applications along its highways since 2009. An individual installation is
characterizedaspossessingauniquebeginningandendingmilepointalongagivenhighwayroute.Each
installation took into account HFST applications on lanes in both directions of travel and were not
counted as separate installations (assuming they had the same beginning and end). HFST was most
oftenappliedtohorizontalcurvesandinterstateramps.HFSTinstallationswerealsoidentifiedforafew
approachestostop-conditionintersections.
EarlyHFST results have proved promising. Several case studies demonstrated significant decreases in
trafficcrashesfollowingtheinstallationofHFST.Ina2009example,KYTCinstalledHFSTtoanOldham
Countyhorizontalcurvethatexperiencedahighnumberofcrashes.Sincethattime,thecurve’sannual
crashratedroppedfrom18.7to1.6crashesperyearovera6-yearperiod(datacollectedatthreeyear
intervals prior to and following installation). In another case, KYTC applied HFST to a high-crash
intersectioninKnoxCountyin2011.Earlyresultsdemonstratedacrashreductionofnearly50percent.
Additionalpost-installationcrashdataisrequiredforfurthervalidation.15
This project captured the locations and various characteristics associatedwith HFST installations and
consolidatedthedataintoasingle,comprehensivedatabase.KTCresearcherscoordinatedeffortswith
9
the KYTC to inventoryHFST installations across Kentucky. In this effort, KTC identified high-risk crash
areasacrossthecommonwealthutilizingHighwaySafetyManual(HSM)methodologicalprocedureson
Kentucky’scrashdata.Usingthenetworkscreeningtechniques,aprioritizedlistwasdevelopedshowing
locationswiththemostpotentialforcrashreduction.KYTCcollectedthislistandusedittoformulatea
HFSTtreatmentprojectlist.Thisprojectlistformedthebasisforapprovaloffuturecontractproposalsat
locationsrequiringHFSTinstallation.
TheHighwaySafetyImprovementProgram(HSIP)withinKYTC’sDivisionofTrafficOperationsfundsand
executes theHFSTprogram. KTCcoordinatedwithHSIP to collect theHFSTdata. TheHSIPManager
maybereachedbyphoneat(502)564-3020or(502)782-5534.
KYTC provided KTC with a spreadsheet dataset. It contained a collection of high friction surface
treatment applications, installed from 2009 to the present. This spreadsheet included the following
categories:
• IdentificationNumber(ID)
• District
• County
• Route
• Milepoint,Beginning
• Milepoint,End
• Site
• Length
• Width
• Area(SquareYards)
• Description(Direction)
• Product
• InstallDate
KTC collected and sorted HFST attributes into a separate spreadsheet database. The KTC database
consistedofthefollowingcategoriesthatweredeemednecessaryforafocusonsafety:
• Identificationnumber
• Districtnumber
• County
• Route
• Milepoints(BeginningandEnd)
• Quantity(Length,Width,SurfaceArea)
• Directionoftravel
• InstallDate
HFSTdatawerethenuploadedintoArcMap.ThisplatformallowedKYTCuserstovisualizethelocation
ofallHFSTinstallationsacrossKentucky.Inaddition,theusercouldclickontheHFSTboundarylineto
seealloftheattributesassociatedwiththatapplicationsuchascounty,route,andmilepoints.Allofthe
HFSTinstallationsareshowninAppendixA,Figure12.
10
Chapter4:RumbleStripes4.1IntroductionRumble stripes are a safety treatment that prevents roadway departures from the vehicular lane of
travel.Errantvehiclesdepartalaneoftravelbyeitherleavingtheouteredgeofaroadwayorcrossing
overthecenterlineintoanopposinglaneoftraffic.Similartorumblestrips,rumblestripesconsistofa
seriesofindentationsconstructedalongtheroadwaysurfacewhichreactwithvehicletirestoproducea
distinct sound for thedriver.However, rumble stripes gobeyond conventional rumble strips because
paint is applied on the top, for increased visual awareness. Rumble stripes act as roadway safety
treatmentsbyalertingerrantdriversoflanedeparturethroughthesevisualandauditorycues.
Researchstudiesdemonstratebothrumblestripsandrumblestripesreducecrashfrequencies. Inone
study, a joint team of researchers from the Midwest Research Institute and the Pennsylvania
TransportationInstituteshowedsignificantdecreasesincrashratesfollowingtheinstallationofcenter
line and shoulder rumble strips. The study's research findings indicated a 45 percent and 64 percent
reductionincrashesonruraltwo-laneroadsandurbantwo-laneroads,respectively,afterinstallationof
centerline rumble strips. Similarly, crash ratesdecreasedby36percent and17percent for rural two-
laneroadsandruralfreeways,respectively,afterinstallationofshoulderrumblestrips.16Consequently,
statedepartmentsoftransportation,includingKYTC,haveconstructedthesetreatmentstohelpreduce
thenumberoflanedeparturesandassociatedcrashes.
4.2CompositionandFunction
Rumblestripesbeginasaseriesofindentationsordepressionsconstructedintothepavementalongthe
edgeoftheroadwayorontopofthecenterline.Atthisstage,thissafetytreatmentiscategorizedasa
rumblestrip.17Typicalrumblestripecharacteristicsinclude:
• Widthsrangingfrom5to7inches,
• Lengthsrangingfrom12to16inches,
• Depthof0.5inchbelowthepavementsurface,and
• Separatedbyanapproximate12-inchspacing.18
The seriesof indentationsare locatedperpendicular to thedirectionof vehicle trafficand reactupon
impact with a vehicle’s tires to produce a distinct sound and accompanying vibration. This alerts a
fatigued or distracted driver that lane departure is imminent so he or she can make the necessary
course corrections and safely reenter the lane of travel. Rumble stripes receive additional safetymodificationsintheformofapavementmarkingpainteddirectlyoverthetop.Pavementmarkingsare
simply the painted lines indicating the travel lane, both for the centerline and the edgeline. Rumble
stripesalsoprovide increaseddelineationduringrainevents.Microbeadscontainedwithintherumble
stripes enhance the refractive properties of the markings during wet road conditions and assist in
redirectinglightbacktoitssource. Thisresults inincreasednighttimepavementmarkingvisibilityfor
thedriver.
Previously,rumblestripswereplacedparallelandoffsettotheroadway’spavementmarkings.Rumble
strips would not notify the driver until the vehicle had already departed the lane of travel. In the
modifiedrumblestripes,driversarenotifiedinreal-timewhentheycrossoverthetravellanepavement
markings.Theconvergenceoftherumblestripeswithlanepavementmarkingsensuresdriversreceive
11
instantaneousauditoryandvisualcuesatthemomentoflanedeparture.Illustrationsforcenterlineand
edgelinerumblestripesareshowninthefiguresbelow.
Figure4:CenterlineRumbleStripes
Source:U.S.Hwy60,FranklinCounty,KY
Figure5:EdgelineRumbleStripes
Source:KYHwy55,HenryCounty,KY
12
4.3Inventory
KYTChas installedrumblestripsformanyyearsandonlyrecentlytransitionedtothemodifiedrumble
stripe. Since 2008, KYTC has installed rumble stripes across 750 locations over 2,500 miles. Rumble
stripesmaybeinstalledalongtheroadwaycenterline,edgeline,orboth.Inthisinventory,aninstallation
isdefinedasastaticrumblestripeconditionalongagivensegmentofroadway.Asegmentofroadway
starts at a beginning mile point (BMP) and ceases at the ending milepoint (EMP). For example, a
centerlinerumblestripe installed fromBMP0.0 toEMP5.0wouldconstituteasingle installation.The
centerline rumble stripe continues along the highway but an additional edgeline rumble strip is also
constructed fromBMP5.1 toEMP10.0.This secondsegmentofhighwayalsocountsasan individual
rumblestripeinstallation.Inthiscase,theadditionofanedgelinerumblestripeparalleltotheexisting
centerline rumble stripe represents a change in the static condition and therefore constitutes a new
installationscenario.This installationnomenclature isusedbecausethis represents thebestapproach
for inputtingdataintoArcMap.ArcMapmust interpretdatathroughassignedmilepointsandroadway
locations(i.e.,centerlineoredgeline)inordertoaccuratelyplotrumblestripeinstallations.
KTCutilizedmultipledatasourcestocompiletherumblestripedatabaseusedfortheArcMapinventory.
Early on, KTC researchers determined that a comprehensive source of data for rumble stripe
installationswas lacking.KYTChasonly constructed rumble stripe treatments in recent yearsandhas
not yet developed internal processes to capture and collect rumble stripe locations. KTC researchers
needed to develop different data collection methods to overcome the initial data challenges.
Consequently, KTC researchers identified multiple sources to construct the initial rumble stripe
inventory suchas: KYTC contract archives, interviewsanddiscussions,previousKTC research studies,
andvisualinspections.Thecompilationofthesedatasourcesweredividedintothefollowingcategories:
(a) Pre-2009 Data, (b) 2009 KTC Study, (c) FY 2011-14 Resurfacing Projects, and (d) 2010 and 2012
RetrofitProjects.Eachrumblestripedatacategorywillbediscussedingreaterdetailbelow.
Pre-2009Data: In2008,KTCconductedaresearchstudyonsnowplowimpactsonpavementmarkers.
One research objective in the study required the examination of existing rumble stripes installations
across the state. Although rumble strips have been used for many years, KYTC had only recently
implementedtherumblestripeprogramandthereforehadonlyinstalledfourrumblestripetreatments.
Eachrumblestripewasplacedalongthecenterlineonfourmajorhighwayswithinthestate.Thefour
locationsandcorrespondinginstallationlengthsinclude:
• MountainParkway(Magoffin,Morgan,andWolfecounties),32.5miles
• HalRogersParkway(Clay,Laurel,Leslie,andPerrycounties),54miles
• AAHighway(Bracken,Greenup,Lewis,Mason,andPendletoncounties),71.3miles
• US31W(JeffersonCounty),5.2miles
Additionaldetailson these rumble stripesand themethodsused toobtain themcanbe found in the
originalresearchstudyEvaluationoftheUseofSnowplowableRaisedPavementMarkers(KTC-09-09).19
2009 KTC Study: In 2009, KTC examined additional rumble stripe installations across the state. This
research effort focused on those rumble stripes installed since the release of the initial KTC 09-09
researchstudy.Intotal,rumblestripeshadbeeninstalledat10locationsalongtheedgelineontwo-lane
roads.Thisrumblestripegroupincludedthefollowing:
13
Table1:RumbleStripeInstalls,KTC-10-01
Highway County MilesU.S.51 Ballard 5.5
KY36 Bath 8.0
U.S.42 Gallatin 5.6
KY39 Garrard 5.3
U.S.421 Henry 6.4
KY699 Leslie 9.4
KY7 Letcher 2.6
KY59 Lewis 11.0
KY7 Magoffin 3.7
U.S.62 Nelson 7.6
Source:KentuckyTransportationCenter(KTC-10-01/SPR330-07-41)20
AdditionaldetailsregardingtheserumblestripescanbefoundintheoriginalresearchstudyEvaluationofRumbleStripes(KTC-10-01).
FY 2011-15 Resurfacing Projects: In 2011, KYTC broadened the rumble stripe program for wide-scale
implementation across the state.21 The dataset for rumble stripe construction projects during these
fiscal years was obtained from KYTC historical project archives. The KYTC Division of Construction
Procurementcollectsandarchivesallauthorizedconstructionprojectseachfiscalyear,includingrumble
stripingprojects.KTCobtainedacopyofKYTC'sprojectarchive listandsearched theentire list forall
rumble stripe projects installed between fiscal years 2011 through 2015.22 These projects specifically
involved installations on new pavement and did not include any existing pavements retrofitted with
installedrumblestripes.Theprojectarchiveslistincludedthefollowingcategories:
• ContractIdentificationNumber(ID)
• ProjectNumber
• ProjectLocation
• WorkDescription
• ProjectDescription
• ProjectRoadName
• ProjectCost
• DateofLetting
Rumble stripe installations for new resurfacing projects are required to follow Active Sepias 2012
drawing specifications for all installations. The Active Sepias list provides updates to the Standard
Drawings which are not yet reflected in the Standard Drawings. KYTC has detailed sheets for both
centerlineandshoulderrumblestrips.Asdescribedpreviously,rumblestripsformthebasisofrumble
stripes and therefore, these detailed sheets are also used during rumble stripe installations. Select
portionsofboththecenterlineandshoulderrumblestripdetailsheetsareshowninthefiguresbelow.
14
Figure6:CenterlineRumbleStrip,SepiaSheet010
Source:KentuckyTransportationCabinet23
Figure7:ShoulderRumbleStrips,SepiaSheet011
Source:KentuckyTransportationCabinet24
2010 and 2012 Retrofit Projects: In select cases, KYTC installed rumble striping on existing roadway
pavements.Thesecaseswere let in fiscalyears2010and2012.KTC inspectorsexaminedthesites for
thepresenceofretrofittedrumblestripes.Datacollectedduringtheseinspectionsincludedthedateof
inspection, route identification number (ID), county, andmilepoints installed. Collectively, all rumble
stripe data was displayed using ArcMap for the final inventory output. All of the rumble stripe
installations in the state are shown in Appendix A, Figure 13.
15
Chapter5:SafetyEdge
5.1Introduction
TheSafetyEdgetreatmentreducestheslopeangleat thepavement’sedge.Thisallowserrantdrivers
leavingthepavementtosafelyreturn.Manyroadwaysexperienceasteepverticaldrop-offinelevation
betweenthepavedsurfaceof thetravelcourseandtheadjacentgradedsurface.Thissharpelevation
differencemakes it difficult for drivers to safely navigate the vehicle back onto the roaddue to “tire
scrubbing”. This condition frequently leads thedriver toover-steer and increases theprobability of a
severecrash—collisionsoroverturningofthevehicle.ResearchstudieshaveshowntheSafetyEdge is
effectiveinallowingerrantvehiclestosmoothlyreentertheroadway,evenathigherspeeds.
5.2CompositionandFunction
TheSafetyEdgeformsasmooth,mild-slopetransitionontheouterpavementedgedirectlybordering
thenewlygradedmaterial.Thispavementslopeliesata30degreeangleabovetheoldgradedmaterial
elevation. This reduces the excessive drop-off typically associated with conventional roadways.
Following resurfacing, newly graded material is installed flush with the new pavement surface in
accordancewithstandardconstructionpractices.Anyfuturedegradationof thisgradedmaterialat its
boundarywiththeroadwayexposestheSafetyEdgeandallowserrantvehiclestosafelytransitionback
ontotheroadway.Anillustrationofthisconceptisshowninthefigurebelow.
Figure8:SafetyEdgeAngle
Source:FHWA,SafetyEdge25
TheSafetyEdgecanbeinstalledusingeitherasphaltconcrete(AC)orPortlandcementconcrete(PCC)
materials.26SpecialdevicesareattachedtoexistingpavingconstructionequipmenttoinstalltheSafety
Edge.InspectorsverifytheangleoftheSafetyEdgeuponinstallationtoensurequalitycontrol.Figures7
and8 below compare newly constructedpavement surfaces (using the safety edge transition)with a
conventionalroadwayboundary(withoutthesafetyedge).
16
Figure9:PavementwithSafetyEdge
Source:FHWA,SafetyEdgePresentation27
Figure10:PavementwithoutSafetyEdge
Source:FHWA,SafetyEdgePresentation28
17
5.3Inventory
KTCconductedacomprehensivesearchacrossallKYTCprojectproposalsapprovedfromJanuary1,2011
toSeptember30,2015togeneratetheSafetyEdgeinventory.KYTCprojectproposalsnotifycontractors
and businesses on upcoming KYTC-sponsored projects and solicit bids for consideration. Bids are
evaluatedbyKYTCusingselectcriteriabeforeacontractorisawardedtheproject.Eachprojectproposal
contains relevant informationneededby contractors to evaluate the scope and costs for theproject.
Project proposal details may include, but are not limited to, the following: location (route, county),
letting date, and the scope of work. In this case, KTC researchers only examined those proposals
containingaSafetyEdgeconstructionrequirementcontainedwithintheoverallscopeofwork.
The start date of January 1, 2011was selected since Safety Edge installations did not occur prior to
2011. Theenddate represented the completiondateof this report. Todownloadaproject proposal,
first, the researcher navigated to the KYTC website and selected “Construction Procurement”
underneaththedrop-downmenuoption“Business.”29ConstructionProcurementrepresentedtheKYTC
Division responsible for letting projects for construction. On thiswebpage, the researcher selected a
specificlettingdateresidingwithintheselectedtimeperiodofinterest(2011-2015).Lettingdateswere
shownunderthe“Lettings”headerandshowedupashyperlinks.Next, the“LettingDetails”webpage
provided“ProposalInformation”forallprojectproposalscontainedwithinthelettingdate.
Whenallprojectproposalswereanalyzed todeterminewhichprojects involved installationofoneor
moreSafetyEdges,thecompletenumberofKYTCprojectstotaled3,826.Thisnumberincludedanytype
ofprojectKYTCreleasedforbid.Uponfurtherexamination,52projectswereremovedfromthisinitial
total after determining those contracts had been formally withdrawn (or removed from contract
bidding). An Adobemulti-file searchwas used on the remaining 3,774 project proposals. This search
identifiedanyfilescontainingtheterm“SafetyEdge”andrevealed140projectproposalsmeetingthis
criteria.Eachproposalwassubsequentlyscannedtoconfirmtheproject’s scopeofwork required the
actual installationofaSafetyEdge.Eachof the140projectproposalscontainedstipulations requiring
installationofaSafetyEdge/swithinthescopeofwork.However,oneprojectproposalwasidentifiedas
afalsepositiveintermsofinventoryapplicability.Inthiscase,theprojectinstalledasafetyedgeatan
airport and therefore, did not fit the scope of this inventory covering roadside safety. It was
subsequentlyeliminatedfromtheinventorydatabasetoarriveatafinalsafetyedgeproposalcountof
139.
SeveralprojectproposalsrequiredtheinstallationofmorethanoneSafetyEdgealongagivenroute/s.
Inthiscontext,asingleSafetyEdgeinstallationentailedanysingle,continuousSafetyEdgeinstallation
alongaroadwaysegment(asdefinedbymilepoints)withoutaninterruptionorbreakininstallation.A
single project proposal may havemultiple Safety Edge installations spread across multiple routes or
evenalongdifferentsectionswithinthesameroute.Ananalysisusingthismethodologywasneededto
determinetheexactnumberofSafetyEdge installationsoccurringwithinthe139projectproposals.A
thorough analysis of theproject proposals revealed 188 separate Safety Edge installations tookplace
between2011and2015.
KTCresearchersdevelopedaninventoryfromtheSafetyEdges identifiedwithintheapplicableproject
proposals. The attributes were sorted into an Excel spreadsheet that also noted relevant contract
informationandidentifiedlocation.Thisspreadsheetincludedthefollowingcategories:
18
• County
• RouteNumber
• BeginningMilepoint
• EndingMilepoint
• Prefix(USorKYroute)
• ContractIdentificationNumber(CID)
• ContractCallNumber
• DateofLetting
Intotal,alistof147SafetyEdgeprojectswereinstalledduringthistimeperiod,onapproximately580
miles of roadways. Each Safety Edge installation was plotted in ArcMap. All of the Safety Edge
installationsinthestateareshowninAppendixA,Figure14.
19
ConclusionTheKentuckyTransportationCabinetcontinuestoseekoutinnovativemeasuresforimprovinghighway
safety. The installation of recently developed safety measures on existing roadways forms a key
component in that strategy. Safetymeasures such as cable barriers, high friction surface treatments
(HFST), rumble stripes, and Safety Edges have demonstrated tangible reductions in crashes and
fatalities. Studies conducted across the nation have confirmed the reductions. To date, KYTC has
constructednumerousinstallationsovermanymiles:
TypeofInstallation NumberofInstallations MilesofInstallations
CableBarriers 44 265
HighFrictionSurfaceTreatments 112 20
RumbleStripes 750 2,500
SafetyEdges 147 580
Allsafetymeasureinstallationsacrossthestatehavebeencompiledintoacomprehensivedatabasein
the form of an Excel spreadsheet. After ArcMap was used to reference locations of the inventoried
safetytreatments,thisdataservesasinputintoKYTC’sstatewidelinearreferencesystem.Furthermore,
attributes were assigned to each safety treatment type; they are also accessible through ArcMap.
Common attributes collected for the safety measure identification include: district number, county,
route,beginningandendingmilepoints,length,directionoftravel,anddateofinstallation.
Historically, KYTC has not possessed a single, comprehensive database showing the locations and
attributes for the safety measures listed above. The compilation of this comprehensive database
providesKYTCtransportationofficialswithasinglesitethatmonitorsandassessesthedifferentsafety
measuretypes.ThismayprovebeneficialinfutureyearsbyallowingpolicymakersandKYTCofficialsto
fullyevaluateeachofthesafetymeasuretypes.Anevaluationcouldyieldinsightsintoinstallationcosts
and safety outcomes on crashes, giving the ability to compare outcomeswith initial predictions. This
inventoryshouldserveasausefultooltoevaluatecostsandbenefitsofsafetymeasuresinstalledacross
Kentucky.
AppendixA
20
AppendixAFigure11:CableBarriers
AppendixA
21
Figure12:HighFrictionSurfaceTreatments
AppendixA
22
Figure13:RumbleStripes
AppendixA
23
Figure14:SafetyEdges
24
References1FederalHighwayAdministration(FHWA),OfficeofSafetyPrograms.(2015,September24).RoadwayDepartureSafety.Retrievedfrom:http://safety.fhwa.dot.gov/roadway_dept/2FederalHighwayAdministration(FHWA),OfficeofSafetyPrograms.MedianBarriers.Retrievedfrom:http://safety.fhwa.dot.gov/roadway_dept/policy_guide/road_hardware/ctrmeasures/median_barriers/ObtainedonDecember10,2014.3FederalHighwayAdministration(FHWA),OfficeSafetyPrograms.CableBarriers.Retrievedfrom:http://safety.fhwa.dot.gov/roadway_dept/policy_guide/road_hardware/ctrmeasures/cable_barriers/ObtainedonDecember10,2014.4FederalHighwayAdministration(FHWA),FHWAResourceCenter.CableMedianBarriers.Retrievedfrom:https://www.fhwa.dot.gov/resourcecenter/teams/safety/safe_mrt_cable.cfmObtainedonSeptember24,2015.5MinnesotaDepartmentofTransportation.CableMedianBarriers.Retrievedfrom:http://www.dot.state.mn.us/trafficeng/reports/cmbarrier.htmlObtainedonDecember10,2014.6KentuckyTransportationCabinet,DivisionofPlanning.Centerlines.Retrievedfrom:http://transportation.ky.gov/Planning/Pages/Centerlines.aspxObtainedonAugust1,2015.7KentuckyTransportationCabinet,Maps.ActiveHighwayPlan.Retrievedfrom:http://maps.kytc.ky.gov/photolog/?config=ActiveHighwayPlanObtainedonDecember9,2014.8Milstead,R.X.,Qin,B.,Katz,J.,Bonneson,M.,Pratt,J.Miles,andP.Carlson.(2011,June).ProceduresforSettingAdvisorySpeedsonCurves.(FHWA-SA-11-22).FederalHighwayAdministration,Washington,D.C.9FederalHighwayAdministration.IntersectionSafety.U.S.DepartmentofTransportation,Washington,D.C.,2009.Retrievedfrom:http://safety.fhwa.dot.gov/intersection/10FederalHighwayAdministration.ARoadSurfaceTreatmentforCriticalSafetySpotLocationsthatHelpsVehiclesStayinTheirLane,(pp.4).U.S.DepartmentofTransportation,Washington,D.C.Retrievedfrom:https://www.fhwa.dot.gov/everydaycounts/edctwo/2012/pdfs/hfst_brochure.pdf11Agent,Kenneth.(2015,September).KentuckyTransportationCenter,UniversityofKentucky.12FHWA.RoadSurfaceTreatment...,Pg.313FHWA.RoadSurfaceTreatment...,Pg.514AmericanTrafficSafetyServicesAssociation.(2013,February).SafetyOpportunitiesinHighFrictionSurfacing.Fredericksburg,VA.15FederalHighwayAdministration.ProjectCaseStudy:KentuckyTransportationCabinet.U.S.DepartmentofTransportation,Washington,D.C.Retrievedfrom:https://www.fhwa.dot.gov/everydaycounts/edctwo/2012/pdfs/edc_hfst_ky.pdf
25
16Torbic,DarrenJ.(2009).NCHRPReport641:Guidanceforthedesignandapplicationofshoulderandcenterlinerumblestrips,641.TransportationResearchBoard.17Rumblestripescanbeeithermilledorraised.Milledrumblestripesarethemostcommonandinvolvetheprocessofcreatingdepressionsorgroovesintotheroadwaysurface.Raisedrumblestripeselevatethemarkersabovetheexistingpavementsurface.MilledrumblestripesareusedextensivelyinKYTCduetotheireaseofmaintenanceforsnowplowremovalandwillbeonlydiscussedhere.Notsurethisqualifiesasareference.18FederalHighwayAdministration,OfficeofSafety.RumbleStripsandRumbleStripes:DesignandConstruction.Retrievedfrom:http://safety.fhwa.dot.gov/roadway_dept/pavement/rumble_strips/design-and-construction.cfmObtainedonMay1,2015.19Agent,Kenneth&Green,Eric.(2009,April).EvaluationoftheUseofSnowplowableRaisedPavementMarkers(KTC-09-09/SPR330-07-31).KentuckyTransportationCenter,UniversityofKentucky.20Agent,Kenneth.KTC-10-01/SPR330-07-41,EvaluationofRumbleStripes,KentuckyTransportationCenter,UniversityofKentucky.January2010.21Thestatefiscalyear(FY)beginsonJuly1andendsonJuly31.ThefirstletcontractforrumblestripesinthiscategorygroupwasonAugust27,2010.Notsurethisqualifiesasareference.22KYTCDivisionofConstructionProcurementprojectarchiveslist.Retrievedfrom:http://transportation.ky.gov/Construction-Procurement/Pages/default.aspxSelect"ProjectArchives"under“Resources”columnontheright-sideofthepage.23KentuckyTransportationCabinet.OfficeofHighwayDesign,ActiveSepias2012,CenterlineRumbleStrips.Retrievedfrom:http://transportation.ky.gov/highway-design/pages/sepias2012.aspx.ObtainedonSeptember24,2015.24KYTC.ActiveSepias2012,ShoulderRumbleStrips.25FederalHighwayAdministration.AcceleratingInnovation—SafetyEdge.Retrievedfrom:http://www.fhwa.dot.gov/everydaycounts/technology/safetyedge/brochure.cfmObtainedonSeptember16,2015.26FederalHighwayAdministration.(2012,January5).SafetyEdgeDesignandConstructionGuide.Retrievedfrom:http://www.fhwa.dot.gov/everydaycounts/technology/safetyedge/guidancepolicy.cfm#tab327Tenges,Ryan&Julian,Frank.TrafficandSafetyAcademy,TheSafetyEdgePresentation,Slide13.FederalHighwayAdministration,KYDivision.ObtainedonSeptember1,2015.28FHWA.TrafficandSafetyAcademy.Slide13.29KentuckyTransportationCabinet.ConstructionProcurement.Retrievedfrom:http://transportation.ky.gov/Construction-Procurement/Pages/default.aspxObtainedonSeptember17,2015.