Unit 10RoadDesign-HorizontalandVerticalAlignmentText1Background Onedefinitionofavisuallyattractiveandunobtrusivehighwayisthedegreetowhichthehorizontalandverticalalignmentsoftheroutehavebeenintegratedintoitssurroundingnaturalandhumanenvironments[1].Thistakescarefulplanninganddesign,asnotedintheAASHTOGreenBook:Coordinationofhorizontalalignmentandprofileshouldnotbelefttochancebutshouldbeginwithpreliminarydesign,duringwhichadjustmentscanreadilybemade...Thedesignershould-studylong,continuousstretchesofhighwayinbothplanandprofileandvisualizethewholeinthreedimensions. Thisapplicationofaholisticapproachtohighwaydesign,wheretheroadisintegratedintoitssurroundings,separatestheoutstandingprojectfromonethatmerelysatisfiesbasicengineeringdesigncriteria.AnexcellentdescriptionofthisholisticdesignprocessiscontainedinthepublicationAestheticsinTransportation,fromwhichthefollowingisexcerpted:Ageneralrulefordesignersistoachievea“flowing”line,withasmoothandnaturalappearanceintheland,andasensuous,rhythmiccontinuityforthedriver.Thiseffectresultsfromfollowingthenaturalcontoursoftheland,usinggracefulandgradualhorizontalandverticaltransitions,andrelatingthealignmenttopermanentfeaturessuchasriversormountains.Text2HorizontalandVerticalAlignmentConsiderations Thegreatestopportunitiesforinfluencingthehorizontalandverticalalignmentsofahighwayoccurduringtheplanningandpreliminaryengineeringphasesassociatedwithanew-locationfacility.Thedesignsofsuchfacilitieshavethemostdramaticeffectsonthenaturalandhumanenvironmentsthroughwhichtheypass. Themoretypicaldesignproblemfacedbytoday’shighwayengineersistheimprovementofanexistinghighwayorstreet.Inmanyinstances,thebasicalignmentsmayhavebeenestablishedwellover100yearsago.Regardless,thesamebasicdesignprincipleswithrespecttohorizontalandverticalalignmentscan,however,beappliedtobothnewandexistingfacilities. Importantpointstoconsiderregardinghorizontalandverticalalignmentsarethattheyshouldbeconsistentwiththetopography,preservedevelopedpropertiesalongtheroad,andincorporatecommunityvalues[2].Thesuperioralignmentsareonesthatfollowthenaturalcontoursofthelandanddonotaffectaesthetic,scenic,historic,andculturalresourcesalongtheway.Constructioncostsmaybereducedinmanyinstanceswhenlessearthworkisneeded,andresourcesanddevelopmentarepreserved.Itisnotalwayspossible,however,toavoidhavinganimpactonboththenaturalandhumanenvironments.TextThatiswhythesuperioralignmentsincorporateinputreceivedbythecommunitythroughaparticipatorydesignprocess. Whenpossible,thealignmentshouldbedesignedtoenhanceattractivescenicviews,suchasrivers,rockformations,parks,historicsites,andoutstandingbuildings.ThedesignationofcertainhighwaysasscenicbywaysrecognizestheimportanceofpreservingsuchfeaturesalongourNation’sroadways. Equallyimportantastheconsiderationofthehorizontalalignmentisthatofthefacility’sverticalalignment[3].Anumberoffactorsinfluencetheverticalalignmentofahighway,includingthefollowing:(1)Naturalterrain;(2)Minimumstoppingsightdistancefortheselecteddesignspeed;(3)Thenumberoftrucksandotherheavyvehiclesinthetrafficstream;(4)Thebasicroadwaycross-section;i.e.,twolanesversusmultiplelanes;(5)Naturalenvironmentalfactors,suchaswetlandsandhistoric,cultural,andcommunityresources.Text3CombinationofHorizontalandVerticalAlignment Theinterrelationshipofhorizontalandverticalalignmentisbestaddressedintheroutelocationandpreliminarydesignphasesofaproject.Atthisstage,appropriatetradeoffsandbalancesbetweendesignspeedandthecharacteroftheroad-trafficvolume,topography,andexistingdevelopment-canbemade.Amistakeoftenmadebyinexperiencedengineersisdesigningthehorizontalalignmentfirstandthentryingtosuperimposethedesignontoaverticalprofile.Becausetheymustbecomplementary,horizontalandverticalgeometriesmustbedesignedconcurrently.Uncoordinatedhorizontalandverticalgeometriescanruinthebestpartsandaccentuatetheweakpointsofeachelement.Excellenceinthecombinationoftheirdesignsincreasesefficiency,andsafety,encouragesuniformspeed,andimprovesappearance-almostalwayswithoutadditionalcost. Onetooltoassistincoordinatinghorizontalandverticalgeometriesistheuseofcomputer-aideddesign(CAD).CADenableshighwaydesignerstoquicklyassesstheinterrelationshipsbetweenhorizontalandverticalalignment,particularlyinareasofdifficultterrain. Properconsiderationofthesebasicdesignconsiderationswillhelptoensurethatbothnew-locationfacilitiesandimprovementstoexistinghighwaysfitharmoniouslyintotheirsurroundings[4].Text(1)Issues Therearenumerousexamplesaroundthiscountryofexcellenceinintegrationofthehorizontalandverticalalignmentsofhighwaysintotheirsurroundings.Unfortunately,herearealsoexamplesofneworwidenedhighwaysthathavescarredarurallandscapeordisruptedanestablishedcommunity.Whilethesepastactionscannoteasilyorinexpensivelyberectified,futureproblemscanbeavoidedbyapplyingtheprinciplesoutlinedaboveandthecreativeapproachesdetailedbelow.(2)AvoidingImpactonAdjacentNaturalandHumanEnvironments ParticularlyduringtheeraofInterstateconstructionfromthe1950’stothe1980’s,anumberofinstancesofnewhighwayconstructionhadadevastatingimpactoncommunitiesandareasofenvironmentalsensitivity.Itisreadilyacknowledgedthattherewillbesomedegreeofphysicalimpactonthesurroundingsassociatedwiththeconstructionofanynewlocationhighwayormajorreconstructionorwideningofanexistinghighwayfacility.However,fromtheperspectiveofhorizontalandverticalalignment,muchofthisimpactcanandshouldbealleviated.Text(3)Solution Impactonthesurroundingenvironmentcanbeminimizedbycarefulattentiontodetailduringtheroutelocationandpreliminarydesignphasesandawillingnessofallconcernedpartiestoworktogethertowardacommongoal.Forexample,minoradjustmentstotheoriginallyproposedhorizontalandverticalalignments(combinedwiththeuseofshortsectionsofretainingwall)alongtheLincolnBeachParkway(U.S.Route101)inOregoneliminatedtheneedtoacquireanyoftheadjacenthomesandbusinesses. Similarly,aminorhorizontalalignmentshiftatthebeginningoftheprojectallowedfortheHollisterBypass(SR156)inSanBenitoCounty,CA,toavoidaffectinganumberofhistoricproperties. Theuseofa“cut-and-cover”design,wherebytheroadwayisplacedbelowtheexistinggroundlevelandcoveredoverwithapark,building,orotherpublicspacecanhelptoavoidnegativeimpact[5].LakePlaceParkinDuluth,MNandotherpublicparksweretheresultofcut-and-covertunnelsthatnotonlysavedhistoricpropertiesbutalsogavepedestriansimprovedaccesstoLakeSuperior. Inmanycases,thereisapotentialfordesigningadividedhighwaywithindependenthorizontalandverticalalignmentsforeachdirectionoftraffic.Text4CoordinationbetweenHorizontalandVerticalAlignment Whenhorizontalandverticalalignmentsaredesignedseparatelyfromoneanother,unnecessarilylargecutsandfillsmayberequired,resultinginverydramaticandoftenvisuallyundesirablechangestothenaturallandscape. Solution: Oneofthewaystoensurethemosteffectivecoordinationofhorizontalandverticalalignmentisthroughtheuseofamultidisciplinarydesignteamduringtheplanningandengineeringphasesofaproject.Onsuchprojectsas1-66inFairfaxandArlingtonCountiesinVirginia,thecombinedexpertiseoflandscapearchitects,urbandesigners,structuralengineers,andhistoricpreservationists,inadditiontocivilengineersandhighwaydesigners,hasresultedinsuperiorhighwayimprovementprojects. Theconceptofusingamultidisciplinarydesignteamisnotnew;itwaspioneeredintheearly1900’sduringtheplanninganddesignoftheBronxRiverParkwayinWestchesterCounty,NY.Afteraperiodofuseprimarilyonlarge-scaleorcontroversialprojects,thisapproachhascomebackintomoregeneralapplicationasawaytoachievecommunityconsensus.NewWordsandphrasesalignmentn.（道路）線型，定線horizontalalignment平面線型verticalalignment縱斷面線型routen.路線；航線；通道AmericanAssociationofStateHighwayandTransportationOfficials(AASHTO)美國國家公路與運輸協會profilen.縱斷面；側面；輪廓preliminarydesign(phase)初步設計（階段）contourn.等高線；輪廓transitionn.過渡；轉變；轉換earthworkn.土方工程，挖土terrainn.地形，地勢；領域；地帶sightdistance視距stoppingsightdistance停車視距cross-sectionn.橫斷面；橫截面lanen.車道；航線；小巷twolanes雙車道m(xù)ultiplelanes多車道tradeoffn.折衷方案；權衡NewWordsandphrasestopographyn.地勢；地形superimposevt.添加，附加；重疊；安裝geometryn.幾何（學）computeraideddesign（CAD）計算機輔助設計widenedhighway擴寬的公路retainingwall擋土墻，護壁；護岸cut-and-cover下挖加蓋板landscapen.景觀，風景v.美化景觀landscapearchitect景觀設計師urbandesigner城市規(guī)劃設計師structuralengineer土木工程師Notes1.Onedefinitionofavisuallyattractiveandunobtrusivehighwayisthedegreetowhichthehorizontalandverticalalignmentsoftheroutehavebeenintegratedintoitssurroundingnaturalandhumanenvironments 一條具有視覺誘導性和線性平順性的公路，要使得平縱線形與周圍人文地理環(huán)境相協調。2.Importantpointstoconsiderregardinghorizontalandverticalalignmentsarethattheyshouldbeconsistentwiththetopography,preservedevelopedpropertiesalongtheroad,andincorporatecommunityvalues 平曲線和豎曲線設計的關鍵是，要綜合考慮實際地形、沿線的發(fā)展建設與社會經濟價值。3.Equallyimportantastheconsiderationofthehorizontalalignmentisthatofthefacility’sverticalalignment 相對于路基工程設施的水平對齊，它的垂直對齊同樣重要，都應該被考慮。4.Properconsiderationofthesebasicdesignconsiderationswillhelptoensurethatbothnew-locationfacilitiesandimprovementstoexistinghighwaysfitharmoniouslyintotheirsurroundings 對這些基本設計原則的適當考慮有助于使新建設施和改進后的原有公路和諧的融入它們的周邊環(huán)境。Notes5.Theuseofa“cut-and-cover”design,wherebytheroadwayisplacedbelowtheexistinggroundlevelandcoveredoverwithapark,building,orotherpublicspacecanhelptoavoidnegativeimpact 采用“隨挖隨填法”設計，使得路線可以布置在已有地面高程以下，可以減少對覆蓋在其上的公園、建筑物或者其他公共空間的不利影響。Exercise（TranslatethefollowingChineseintoEnglish,orEnglishintoChinese）1.Ageneralrulefordesignersistoachievea“flowing”line,withasmoothandnaturalappearanceintheland,andasensuous,rhythmiccontinuityforthedriver.Thiseffectresultsfromfollowingthenaturalcontoursoftheland,usinggracefulandgradualhorizontalandverticaltransitions,andrelatingthealignmenttopermanentfeaturessuchasriversormountains.2.Theuseofa“cut-and-cover”design,wherebytheroadwayisplacedbelowtheexistinggroundlevelandcoveredoverwithapark,building,orotherpublicspacecanhelptoavoidnegativeimpact.LakePlaceParkinDuluth,MN