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TechnicalBulletSeriesonClayBrickPavers

#3–TruncatedDomeADAPaversAbstract–ThisTechnicalBulletdetailstherulesaroundtheuseofTruncatedDomestocomplywithADAandPublicRightOfWay(PROWAG)Guidelines.PineHallBrickTruncatedDomeADApaverscomplywiththeADArequirementfordetectablewarningsforuseinthePublicRightOfWayaccordingtoR304Guidelines.

q Availablein2¼”x4”x8”.StockRedcolor.EnglishEdgecolorsavailableasspecialorder.q AvailableinHeavyVehicular2-3/4”thicknessasaspecialorderq Pavermaybelaidinarunningbondorherringbonepattern.

Picture1:PineHallBrickADAPaver–RedR221–WhereDetectableWarningSurfacesAreRequired

DetectablewarningsurfacesshallcomplywithR304.

AdvisoryR221DetectableWarningSurfaces.Detectablewarningsurfacesarerequiredwherecurbramps,blendedtransitions,orlandingsprovideaflushpedestrianconnectiontothestreet.Sidewalkcrossingsofresidentialdrivewaysshouldnotgenerallybeprovidedwithdetectablewarnings,sincethepedestrianright-of-waycontinuesacrossmostdrivewayapronsandoveruseofdetectablewarningsurfacesshouldbeavoidedintheinterestsofmessageclarity.However,wherecommercialdrivewaysareprovidedwithtrafficcontroldevicesorotherwisearepermittedtooperatelikepublicstreets,detectablewarningsshouldbeprovidedatthejunctionbetweenthepedestrianrouteandthestreet.

Picture1:PineHallBrick’sADAClayPavers

R304DetectableWarningSurfaces

R304.1General.DetectablewarningsshallconsistofasurfaceoftruncateddomesalignedinasquareorradialgridpatternandshallcomplywithR304.

R304.1.1DomeSize.Truncateddomesinadetectablewarningsurfaceshallhaveabasediameterof23mm(0.9in)minimumto36mm(1.4in)maximum,atopdiameterof50percentofthebasediameterminimumto65percentofthebasediametermaximum,andaheightof5mm(0.2in).

AdvisoryR304.1.1DomeSize.Wheredomesarearrayedradially,theymaydifferindiameterwithintherangesspecified.

R304.1.2DomeSpacing.Truncateddomesinadetectablewarningsurfaceshallhaveacenter-to-centerspacingof41mm(1.6in)minimumand61mm(2.4in)maximum,andabase-to-basespacingof17mm(0.65in)minimum,measuredbetweenthemostadjacentdomes.

AdvisoryR304.1.2DomeSpacing.Wheredomesarearrayedradially,theymaydifferincenter-to-centerspacingwithintherangespecified.

R304.1.3Contrast.Detectablewarningsurfacesshallcontrastvisuallywithadjacentgutter,streetorhighway,orwalkwaysurfaces,eitherlight-on-darkordark-on-light.

AdvisoryR304.1.3Contrast.Contrastmaybeprovidedonthefullrampsurfacebutshouldnotextendtotheflaredsides.Manypedestriansusethevisualcontrastatthetoeoftheramptolocatethecurbrampopeningfromtheothersideofthestreet.

R304.1.4Size.Detectablewarningsurfacesshallextend610mm(24in)minimuminthedirectionoftravelandthefullwidthofthecurbramp(exclusiveofflares),thelanding,ortheblendedtransition.

R305.4.2DetectableWarnings.MediansandpedestrianrefugeislandsshallhavedetectablewarningscomplyingwithR304atcurbrampsandblendedtransitions.Detectablewarningsatcut-throughislandsshallbelocatedatthecurblinein-linewiththefaceofcurbandshallbeseparatedbya61cm(2.0ft)minimumlengthofwalkwaywithoutdetectablewarnings.Wheretheislandhasnocurb,thedetectablewarningshallbelocatedattheedgeofroadway.

Foracompletereview,gotowww.access-board.gov.

DetectableWarningsMaybeRetroactive

AccordingtoaspecialistattheDepartmentofJustice,detectablewarningsarerequiredathazardousvehicularareasforareascurrentlyunderconstructionandareasalreadyconstructed.Forthelatterareas,responsiblepartieswillneedtoaccessthefeasibilityofinstallingdetectablewarningsundera“readilyachievable”standard.Duringthesuspensionperiod,manymunicipalitiesaddressedhazardousvehicularareasbyusingcontrastingcolorsandsometypeoftexturechangefromtheadjoiningwalkareas.

Inthoseinstances,changestotruncateddomesmaynotbenecessaryifresponsiblepartiescandemonstrateequivalentfacilitation.EquivalentfacilitationisdefinedinthePublicRigfhts-of-WayGuidelinesas:

R102EquivalentFacilitationNothingintheserequirementspreventstheuseofdesigns,products,ortechnologiesasalternativestothoseprescribed,providedtheyresultinsubstantiallyequivalentorgreateraccessibilityandusability.

StateorLocalGovernmentsMayEnhanceADARequirementsStateorlocalgovernmentsmayaddrequirementstoADAguidelinesinordertoprotectandprovidefortheircitizenry.Whenconflictsbetweenfederalandlocalstandardsarise,thetougherstandardshallbeimplemented.DesignersshouldtakespecialcareinordertoidentifyandunderstandanyspecialprovisionaddedtoanADArequirementbyastateorlocalauthority.