1、外文文獻翻譯(含：英文原文及中文譯文)文獻出處：YHassan.GeometricDesignofHighwaysJAdvancesinTransportationStudies2016,6(1):31-41.英文原文GeometricDesignofHighwaysYHassanA. AlignmentDesignThealignmentofaroadisshownontheplaneviewandisaseriesofstraightlinescalledtangentsconnectedbycircularcurves.Inmodempracticeitiscommontointerpo

2、setransitionorspiralcurvesbetweentangentsandcircularcurves.Thelineshapeshouldbecontinuous,suddenchangesfromflatlinetosmallradiuscurveorsuddenchangeoflonglineendconnectedtosmallradiuscurveshouldbeavoided,otherwiseatrafficaccidentmayoccur.Similarly,arcswithdifferentradiiend-to-end(complexcurves)orshor

3、tstraightlinesbetweentwoarcswithdifferentradiiarebadlinesunlessaneasingcurveisinsertedbetweenarcs.Thelong,smoothcurveisalwaysagoodlinebecauseitisbeaut血llylinedandwillnotbeabandonedinthefuture.However,itisnotidealthatthetwo-wayroadlineshapeiscomposedentirelyofcurves,becausesomedriversalwayshesitateto

4、passthroughcurvedroadsegments.Thelongandslowcurveisusedinthesmallercomers.Ifyouuseashortcurve,youwillsee"kinks."Inaddition,thedesignoftheflatandverticalsectionsofthelineshouldbeconsideredcomprehensivelyandshouldnotbeonlyone.Nomatterwhich,forexample,whenthestartingpointoftheflatcurveisneart

5、hevertexoftheverticalcurve,serioustrafficaccidentswilloccur.Vehiclesdrivingoncurvedsectionsaresubjectedtocentrifugalforce,andtheyneedaforceofthesamemagnitudeintheoppositedirectionduetotheheightandlateralfrictiontooffsetit.Fromtheviewpointofhighwaydesign,thehighorhorizontalfrictioncannotexceedacertai

6、nvalue.Them邸imum,thesecontrolvaluesforacertaindesignspeedmaylimitthecurvatureofthecurve.Ingeneraithecurvatureofac訂cularcurveisrepresentedbyitsradius.Forthelineardesign,thecurvatureisoftendescribedbythecurvature,ie,thecentralanglecorrespondingtothe100-footcurve,whichisinverselyproportionaltotheradius

7、ofthecurve.Anormalroadarchissetinastraightsectionoftheroad,andthecurvesectionissettoasuperhigh,andanexcessivelygradualroadsectionmustbesetbetweenthenorn叫sectionandthesuperhighsection.Theusualpracticeistomaintainthedesignelevationofeachmidlineoftheroadunchanged.Byraisingtheouteredgeandloweringtheinne

8、redgetoformasuperhigh,forthelineshapewherethestraightlineisd汀ectlyconnectedwiththec虹lecurve,thesuperhighshouldneverstartonthestraightlinebeforereachingthecurve.Attheotherendofthecurveatacertaindistancetoreachalltheultra-high.Ifthevehicleisdrivingatahighspeedonarestrictedsectionofroad,suchasastraight

9、lineconnectedwithasmallradiuscirclecurve,drivingwillbeextremelyuncomfortable.Whenthecarentersthecurvesection,thesuperhighstartsandthevehicletiltsinward,butthepassengermustmaintainthebodybecauseitisnotsubjectedtocentrifugalforceatthistime.Whenthecarreachesthecurvesection,centrifugalforcesuddenlyoccur

10、s,forcingpassengerstom狄efurtherpostureadjustments.Whenthecarleavesthecurve,theaboveprocessisjusttheopposite.Afterinsertingtherelaxationcurve,theradiusgraduallytransitionsfrominfinitytoacertainfixedvalueonthecirclecurve,thecentrifugalforcegraduallyincreases,andultra-highlevelsarecarefullysetalongther

11、elaxationcurve,andthecentrifugalforceisgraduallyincreased,therebyavoidingdrivingbumps.Theeasementcurvehasbeenusedonrailwaysformanyyears,butithasrecentlybeenappliedonhighways.Thisisunderstandable.Thetrainmustfollowapreciseorbit,andtheuncomfortablefeelingmentionedabovecanonlybeeliminatedaftertheeasecu

12、rveisused.However,thedriverofacarcanchangethelateralpositionontheroadatwill,andhecanprovidearelaxationcurveforhimselfbym咄ingaroundaboutcurve.Butdoingthisinonelane(sometimesinotherlanes)isverydangerous.Awell-designedrelaxationcurvemakestheaboveroundaboutnessunnecessary.Multi-clustersafetyisameasure,a

13、ndroadsarewidelyusedastransitioncUIVes.Foracircularc田vewiththesameradius,addinganeasingcUIVeattheendwillchangetherelativepositionsofthec田veandthestraightline.Therefore,whetherornottouseaneasingcUIVeshouldbedeterminedbeforefinalalignmentsUIVey.ThestartingpointofthegeneralcUIVeislabeledPCorBCandtheend

14、pointislabeledPTorEC.ForcUIVeswithtransitionc田ves,theusualmarkerconfigurationsare:TC,SC,CS,andST.Fortwo-wayroads,theroadwidthshouldbeincreasedatsharpbends.Thisismainlybasedonthefollowingfactors:1.Thedriverisafraidtogetoutoftheedgeoftheroad.2.Duetothedifferenceinthedrivingtrajectoryofthefrontandrearw

15、heelsofthevehicle,theeffectivelateralwidthofthevehicleincreases;3.Thewidthofthefrontofthevehiclethatisinclinedrelativetothecenterlineoftheroad.Forroadsthatare24feetwide,theaddedwidthisnegligible.Onlyifthedesignspeedis30mil/handthecUIVatureisupto2ft.However,fornarrowroads,wideningisveryimportanteveno

16、nsmoothcUIVesections.Therecommendedwideningvaluesandwideneddesignsareshownin".Highwaylineardesign."B. LongitudinalslopelineTheverticalalignmentofthehighwayanditsimpactonthesafetyandeconomyofvehicleoperationconstituteoneofthemostimportantelementsinhighwaydesign.Verticallinesconsistofstraigh

17、tlinesandverticalparabolasorcircularlinescalledverticalslopelines.Whenagradelinerisesgraduallyfromahorizontalline,itiscalledanuphiliandviceversa,itiscalledadownhillslope.Intheanalysisofslopeandslopecontroi如ignersusuallyhavetostudytheeffectofchangesinslopeonthemidlineprofile.Indeterminingtheslope,the

18、idealsituationisthebalanceofexcavationandfilling,andthereisnolargeamountofborrowersandabandonedparties.Alltheearthmovingiscarrieddownasfaraspossibleandthedistanceisnotlong.TheslopeshouldchangewiththeterrainandbeconsistentwiththedirectionofascentanddescentoftheexistingdrainagesystemInthemountainsthes

19、lope-5shouldbebalancedtominimizethetotalcostIntheplainorgrasslandareastheslopeisapproximatelyparalleltothesurface,buthigherthanthesurfaceatasufficientheighttofacilitatedrainageofthesurface.Ifnecessary,windscanbeusedtoremovesurfacesnow.Iftheroadisapproachingorrunningalongariver,thecurrentheightofthes

20、lopeisdeterminedbytheexpectedfloodlevelInanycase,thegentleslopeshouldbesetattheexcavationsectioncomparedtotheshortverticalsectionconnectingtheshortverticalcurveduetotheupslopedownslope,andthesectionfromthedownslopeupslopeshouldbesetatthefill.Roadsection.Suchagoodlineardesigncanoftenavoidtheforn沮tion

21、ofamoundordepressionoppositetothecurrentlandscape.Otherconsiderationsaremuchmoreimportantwhendeterminingtheverticalslopelinethanwhenfillingthebalance.Studyandmakemoredetailedadjustmentstoadvancedissues.Ingeneral,theslopeofthedesignthatisconsistentwiththeexistingconditionsisbetter,whichcanavoidsomeun

22、necessarycosts.Inslopeanalysisandcontrol,theimpactofslopeonmotorvehicleoperatingcostsisoneofthemostimportantconsiderations.Astheslopeincreases,thefuelconsumptionwillobviouslyincreaseandthespeedwillslowdown.Amoreeconomicalsolutioncanbalancetheannualincreaseintheannualcostofreducingtheslopeandincreasi

23、ngtheannualcostofrunningthevehiclewithoutincreasingtheslope.Theexactsolutiontothisproblemdependsontheunderstandingoftrafficflowandtraffictype,whichcanonlybeknownthroughtrafficinvestigations.Indifferentstates,wherethemaximumlongitudinalgradientisalsoverydifferent,AASHTOrecommendsthatthemaximumlongitu

24、dinalslopebeselectedbasedonthetimeandterrain.Thecurrentdesignhasamaximumlongitudinalgradientof5%atadesignspeedof70mil/h.Atadesignspeedof30mil/h,themaximumlongitudinalslopeisgenerally7%-12%dependingonthetopography.Whenusinglongersustainedclimbs,theslopelengthcannotexceedthecriticalslopelengthwhennosl

25、ow-movingvehicleisprovided.Thecriticalslopelengthcanvaryfrom1700ftin3%gradeto500ftin8%grade.Theslopeofthecontinuouslongslopemustbelessthanthemaximumslopeofanyendsurfaceofthehighway.Usuallythelongcontinuoussingleslopeisdisconnectedandthelowerpartisdesignedasasteepslope,whileapproachingthetopoftheslop

26、eallowstheslopetodecrease.Atthesametime,itisnecessarytoavoidobstructionoftheviewduetotheinclinationofthelongitudinalsection.Them邸imumlongitudinalgradientofthehighwayis9%.Onlywhenthedrainageoftheroadisaproblem,ifthewatermustbedrainedtothesideditchorthedrainageditch,theminimumgradientcriterionisofimpo

27、rtance.Inthiscase,心HTOrecommendsaminimumgradientof0.35%.C. sightdistanceInordertoensurethesafetyofdriving,theroadmustbedesignedtohaveasufficientdistanceinfrontofthedriver'slineofsight,sothattheycanavoidobstaclesotherthantheobstacles,orsafelyovertake.Theline-of-sightisthelengthoftheroadvisibletot

28、hedriverofthevehicle.Twomeanings:"parkingdistance"or"non-passingsightdistance"or"overtakingsightdistance."Nomatterwhathappens,reasonabledesignrequiresthedrivertoseethisdangeroutsideacertaindistance,andbrakethecarbeforehittingit.Inaddition,itisnotsafetothinkthatthevehicl

29、ecanavoiddangerbyleavingthedrivinglane.Becausethiscancausethevehicletolosecontrolortocollidewithanothercar.Theparkingdistanceiscomposedoftwoparts:Thefirstpartisthedistancethatthedrivertakesbeforethedriverfindsanobstacleandbrakes.Inthisdetectionandreactionphase,thevehicletravelsatitsinitialspeed;thes

30、econdpartisthedriver'sPartoftheparkingdistancedependsonthespeedofthevehicleandthedriver'svisualtimeandbrakingtime.Thesecondpartoftheparkingdistancedependsonthespeed,thebrakes,thetires,theconditionsoftheroadsurface,andthelineshapeandslopeoftheroad.Otherwise,thecapacityofthehighwaywillbereduce

31、d,andtheaccidentwillincrease,becausetheirritabledriverwouldriskacollisionandovertakethevehicleifhecannotsafelyovertakethevehicle.Theminimumdistanceinfrontofwhichthedrivercansafelybeseeniscalledtheovertakingdistance.Whenmakingadecisiononwhethertopassornot,thedrivermustcomparethevisibilitydistanceahea

32、dandthedistancerequiredtocompletetheoverta柜ngmovement.Thefactorsthatinfluencehimtom咄eadecisionarethedegreeofcautionindrivingandtheaccelerationperformanceofthevehicle.Duetothesignificantdifferencesbetweenhumans,theovertakingbehavior,whichismainlydeterminedbyhumanjudgmentsandactionsratherthanthemechan

33、icaltheorem,variesgreatlyfromdrivertodriver.Inordertoestablishtheline-of-sightvalueforovertaking,engineersobservedmanydrivers'overtakingbehavior.Between1938and1941,abasicsurveywasestablishedtoestablishastandardofover-sightdistance.Assumethattheoperatingconditionsareasfollows:1. Itisdrivenataunif

34、ormspeedbytheovertakingvehicle.2. OvertakingWhenenteringtheovertakingarea,decelerateafterbeingovertak:en.3. Whenarrivingattheovertakingarea,thedriverneedstoobservethepassingareaforashorttimeandstartovertaking.4. Inthefaceoftheoppositevehicle,theovertakingiscompletedinadelayedstart-upandahurriedturn.

35、Intheovertakingprocess,overtakingacceleratesintheovertakinglaneandtheaveragespeedis10mil/hfasterthanbeingovertaken.5. Whenovertakingreturnstoitsoriginallane,theremustbeasafedistancebetweenitandtheoppositevehicleontheotherlane.Thesumoftheabovefiveitemsistheoversightdistance.中文譯文公路線形設計作者：YHassanA.平面設計

36、道路的線形反映在平面圖上是由一系列的直線和與直線相連的圓曲線構成的。現代設計時常在直線與圓曲線之間插入緩和曲線。線形應是連續的，應避免平緩線形到小半徑曲線的突變或者長直線末端與小半徑曲線相連接的突然變化，否則會發生交通事故。同樣，不同半徑的圓弧首尾相接（復曲線）或在兩半徑不同的圓弧之間插入短直線都是不良的線形，除非在圓弧之間插入緩和曲線。長而平緩的曲線總是良好的線形，因為這種曲線線形優美，將來也不會廢棄。然而，雙向道路線形全由曲線構成也是不理想的，因為一些駕駛員通過曲線路段時總是猶豫。長而緩的曲線應用在拐角較小的地方。如果采用短曲線則會出現“扭結”。另外，線路的平，縱斷面設計應綜合考慮，而不應

37、只顧其一，不顧其二，例如，當平曲線的起點位千豎曲線的頂點附近時將會產生嚴重的交通事故。行駛在曲線路段上的車輛受到離心力的作用，就需要一個大小相同方向相反的由超高和側向摩擦提供的力抵消它，從公路設計的角度看，超高或橫向摩擦力都不能超過某一最大值，這些控制值對千某一規定設計車速可育睬用曲線的曲率作了限制。通常情況下，某一圓曲線的曲率是由其半徑來體現的。而對千線形設計而言，曲率常常通過曲度來描述即100ft長的曲線所對應的中心角，曲度與曲線的半徑成反比。公路的直線地段設置正常的路拱，而曲線地段則設置超高，在正常斷面與超高斷面之間必須設置過度漸變路段。通常的做法是維持道路每一條中線設計標高不變，通過抬

38、高外側邊緣，降低內側邊緣以形成超高對千直線與圓曲線直接相連的線形，超高應從未到達曲線之前的直線上開始，在曲線頂點另一端一定距離以外達到全部超高。如果車輛以高速度行駛在一段受限制的路段，如直線與小半徑的圓曲線相連行車會極不舒服。汽車駛進曲線路段時，超高開始，車輛向內側傾斜，但乘客須維持身體的垂直狀態，因為此時未受到離心力的作用。當汽車到達曲線路段時離心力突然產生，迫使乘客須作進一步的姿勢調整。當汽車離開曲線時，上述過程剛好相反。插入緩和曲線后，半徑從無窮大逐漸過渡到圓曲線上的某一固定值，離b力逐漸增大，沿緩和曲線精心設置超高，離心力平緩逐漸增加避免了行車顛簸。緩和曲線在鐵路上已經使用多年，但在公

39、路上最近才得以應用，這可以理解。火車必須遵循精確的運行軌道，只有采用緩和曲線后，上述那種不舒服的感覺才能消除。然而，汽車司機在公路上可以隨意改變側向位置通過迂回進入圓曲線來為自己提供緩和曲線。但是在一個車道上（有時在其他車道上）做這種迂回行駛是非常危險的。設計合理的緩和曲線使得上述迂回沒有必要。多叢安全為計，公路廣泛采用緩和曲線,對千半徑相同的圓曲線來說，在末端加上緩和曲線就會改變曲線和直線的相關位置，因此應在最終定線勘測之前應決定是否采用緩和曲線。一般曲線的起點標為PC或BC'終點標為PT或EC。對含有緩和曲線的曲線，通常的標記配置為：TCSC,C褥口ST。對千雙向道路急彎處應增加路

40、面寬度，注要基千以下因素：1.駕駛員害怕駛出路面邊緣；2.由千車輛前輪和后輪的行駛軌跡不同，車輛有效橫向寬度加大;3.車輛前方相對千公路中線傾斜而增加的寬度。對千寬度為24ft的道路，增加的寬度很小，可以忽略。只有當設計車速為30miVh,且曲度可達2ft然而，對F較窄的路面，艮I®是在較平緩的曲線路段上，加寬也是很重要的，推薦加寬值及加寬設計見公路線形設計。B.縱坡線公路的豎向線形及其對車連運行的安全性和經濟性的影響構成了公路設計中最重要的要素之一。豎向線形由直線和豎向拋物線或圓曲線組成稱為縱坡線。縱坡線從水平線逐漸上升時稱為上坡，反之，則稱為下坡。在分析坡度與坡度控制中，設計人員

41、通常要研究中線縱斷面上坡度變化的影響。在確定坡度時，最理想的情況是挖方和填方平衡，沒有大量的借方和棄方。所有的運土都盡可能下坡運并且距離不長，坡度應隨地形而變并且與既有排水系統的升，降方向一致。在山區，坡度要使得挖填平衡以使總成本最低。在平原或草原地區坡度與地表近似平行，但高千地表足夠的高度，以利千路面排水，若有必要，可利用風力來清除表面積雪。如公路接近或沿河流走行，縱坡現的高度由預期洪水位來決定。無論在何種情況下，平緩的坡度現要比由短直線段連接短豎曲線構成的不斷變向的坡度線好得多。由上坡向下坡變化的路段應設在挖方路段，而由下坡向上坡變化的路段應設在填方路段。這樣的線形設計較好往往可以避免形成與現狀地貌相反的土堆或是凹地。在挖填方平衡相比，在確定縱坡線時，其他考慮則重要得多。城市項目往往比農村項目要求對控制要素進行更詳盡的研究對高程進行更細致的調整。一般來說設計與現有條件相符的坡度較好，