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1、刘克瑾河南工业大学土木建筑学院土木工程专业英语Lesson3GeometricdesignofhighwaysvTextAAlignmentDesignvalignmentlanm()ntn.队列，线形；v课文A线路设计vTextBGradesv课文B坡度vTextCSightDistancev课文C视距geometric,dmetrk adj.几何学的v1/9Thealignmentofaroadisshownontheplaneviewandisaseriesofstraightlinescalledtangentsconnectedbycircularcurves.Inmodernpra
2、cticeitiscommontointerposetransitionorspiralcurvesbetweentangentsandcircularcurves.vTangenttn(d)()ntn.数切线，数正切adj.切线的，相切的；vinterposentpzvi.干预；插入；vtransitiontrnz()n;trn-;-s-n.过渡；转变；vcircularskjladj.循环的；圆形的；vspiralspar()ln.螺旋；旋涡；螺旋形之物adj.螺旋形的；盘旋的vt.使成螺旋形；使作螺旋形上升vi.盘旋；成螺旋形；螺旋形上升（过去式spiraled/spiralled，过去
3、分词spiraled/spiralled，现在分词spiraling/spiralling，第三人称单数spirals，副词spirally）vspiralcurve螺旋曲线vcircularcurve圆形曲线v1/9Thealignmentofaroadisshownontheplaneviewandisaseriesofstraightlinescalledtangentsconnectedbycircularcurves.vInmodernpracticeitiscommontointerposetransitionorspiralcurvesbetweentangentsandcirc
4、ularcurves.v翻译？v1/9Thealignmentofaroadisshownontheplaneviewandisaseriesofstraightlinescalledtangentsconnectedbycircularcurves.v翻译v公路的线路显示在平面图上，是一系列由圆曲线连接的切线而成。vInmodernpracticeitiscommontointerposetransitionorspiralcurvesbetweentangentsandcircularcurves.v翻译v在现代实践（做法）中，在切线和圆曲线之间插入过渡线（螺旋线）是常见做法。v2/9Al
5、ignmentmustbeconsistent.Suddenchangesfromflattosharpcurvesandlongtangentsfollowedbysharpcurvesmustbeavoided;otherwise,accidenthazardswillbecreated.Likewise,placingcircularcurvesofdifferentradiiendtoend(compoundcurves)orhavingashorttangentbetweentwocurvesispoorpracticeunlesssuitabletransitionsbetween
6、themareprovided.Long,flatcurvesarepreferableatalltimes,astheyarepleasinginappearanceanddecreasepossibilityoffutureobsolescence.However,alignmentwithouttangentisundesirableontwo-laneroadsbecausesomedrivershesitatetopassoncurves.Long,flatcurvesshouldbeusedforsmallchangesindirection,asshortcurvesappear
7、askink.Alsohorizontalandverticalalignmentmustbeconsideredtogether,notseparately.Forexample,asharphorizontalcurvebeginningnearacrestcancreateaseriousaccidenthazard.v2-1/9vAlignmentmustbeconsistent.Suddenchangesfromflattosharpcurvesandlongtangentsfollowedbysharpcurvesmustbeavoided;otherwise,accidentha
8、zardswillbecreated.Likewise,placingcircularcurvesofdifferentradiiendtoend(compoundcurves)orhavingashorttangentbetweentwocurvesispoorpracticeunlesssuitabletransitionsbetweenthemareprovided.vConsistentknsst()ntadj.连续的连续的vradiiredan.半径（radius的复数）vcompoundcurve复合曲线vsharpcurve急弯曲线；锐曲线；急弯；小半径曲线vtransition
9、trnznn.过渡；转变v2-2/9vLong,flatcurvesarepreferableatalltimes,astheyarepleasinginappearanceanddecreasepossibilityoffutureobsolescence.However,alignmentwithouttangentisundesirableontwo-laneroadsbecausesomedrivershesitatetopassoncurves.Long,flatcurvesshouldbeusedforsmallchangesindirection,asshortcurvesapp
10、earaskink.Alsohorizontalandverticalalignmentmustbeconsideredtogether,notseparately.Forexample,asharphorizontalcurvebeginningnearacrestcancreateaseriousaccidenthazard.flatcurve平缓曲线；平滑曲线；大曲率曲线preferableprfrbladj.更好的，更可取的；更胜一筹的pleasingpli:ziadj.令人愉快的；obsolescence,bsulesnsn.废弃；Undesirablendzarb()ladj.不良
11、的；不受欢迎的；kinkkkn.扭结；蜷缩vt.使扭结vi.扭结v2/9Alignmentmustbeconsistent.Suddenchangesfromflattosharpcurvesandlongtangentsfollowedbysharpcurvesmustbeavoided;otherwise,accidenthazardswillbecreated.Likewise,placingcircularcurvesofdifferentradiiendtoend(compoundcurves)orhavingashorttangentbetweentwocurvesispoorpr
12、acticeunlesssuitabletransitionsbetweenthemareprovided.Long,flatcurvesarepreferableatalltimes,astheyarepleasinginappearanceanddecreasepossibilityoffutureobsolescence.However,alignmentwithouttangentisundesirableontwo-laneroadsbecausesomedrivershesitatetopassoncurves.Long,flatcurvesshouldbeusedforsmall
13、changesindirection,asshortcurvesappearaskink.Alsohorizontalandverticalalignmentmustbeconsideredtogether,notseparately.Forexample,asharphorizontalcurvebeginningnearacrestcancreateaseriousaccidenthazard.v3/9Avehicletravelinginacurvedpathissubjecttocentrifugalforce.Thisisbalancedbyanequalandoppositefor
14、cedevelopedthroughsuperelevationandsidefriction.Fromahighwaydesignstandpoint,bothsuperelevationandsidefrictioncannotexceedcertainmaximums,andthesecontrolsplacelimitsonthesharpnessofcurvesthatcanbeusedwithadesignspeed.v3/9Avehicletravelinginacurvedpathissubjecttocentrifugalforce.Thisisbalancedbyanequ
15、alandoppositeforcedevelopedthroughsuperelevationandsidefriction.Fromahighwaydesignstandpoint,bothsuperelevationandsidefrictioncannotexceedcertainmaximums,andthesecontrolsplacelimitsonthesharpnessofcurvesthatcanbeusedwithadesignspeed.centrifugal,sentrfjug()l;sentrfjg()ln.离心机；adj.离心的；centrifugalforce离
16、心力sidefriction横向摩擦superelevation,sju:p,eliveinn.（铁路或公路的）超高;弯面倾斜度;道路弯面加倾度超高超高（SuperelevationSuperelevation）公路平曲线路段，为抵销离心力，提高外侧路面之高度standpointstn(d)pntn.立场；观点sharpness:pnisn.锐利；锐度designspeed设计速度v4/9vUsuallythesharpnessofagivencircularcurveisindicatedbyitsradius.However,foralignmentdesign,sharpnessisco
17、mmonlyexpressedintermsofdegreeofcurve,whichisthecentralanglesubtendedbya100-ftlengthofcurve.Degreeofcurveisinverselyproportionaltotheradius.v4/9vUsuallythesharpnessofagivencircularcurveisindicatedbyitsradius.However,foralignmentdesign,sharpnessiscommonlyexpressedintermsofdegreeofcurve,whichisthecent
18、ralanglesubtendedbysubtendedbya100-ftlengthofcurve.Degreeofcurveisinverselyproportionaltotheradius.vindicatednd,ketdv.表明（indicate的过去分词）；指出；显示vRadiusredsn.半径，半径范围；vintermsof依据；根据；用；按照；在方面；以措词vDegreeofcurve,曲率vsubtendsbtendvt.（弦、边）对（弧、角）；对向vFt-foot,英尺1ft=12in=0.3048mv5/9vTangentsectionsofhighwayscarry
19、normalcrossslope;curvedsectionsaresuperelevated.Provisionmustbemadeforgradualchangefromonetotheother.Thisusuallyinvolvesmaintainingthecenterlineofeachindividualroadwayatprofilegradewhileraisingtheouteredgeandloweringtheinneredgetoproducethedesiredsuperelevation.Wherethealignmentconsistsoftangentscon
20、nectedbycircularcurves,introductionofsuperelevationisbegunontangentbeforethecurveisreached,andfullsuperelevationisattainedsomedistancebeyondthepointofcurve.vtangentsection切线段vcurvedsection曲线段vcrossslope横坡；横向坡度vprofilegrade纵断面坡度vprovisionprv()nn.事先准备；防备（未来的需要）vintroductionof引进；引入vattainedvt.取得，得到，获得（
21、attain的过去式）vpointofcurve曲线起点;曲线始点v5/9vTangentsectionsofhighwayscarrynormalcrossslope;curvedsectionsaresuperelevated.Provisionmustbemadeforgradualchangefromonetotheother.vThisusuallyinvolvesmaintainingthecenterlineofeachindividualroadwayatprofilegradewhileraisingtheouteredgeandloweringtheinneredgetop
22、roducethedesiredsuperelevation.vWherethealignmentconsistsoftangentsconnectedbycircularcurves,introductionofsuperelevationisbegunontangentbeforethecurveisreached,andfullsuperelevationisattainedsomedistancebeyondthepointofcurve.v6-1/9Ifavehicletravelsathighspeedonacarefullyrestrictedpathmadeupoftangen
23、tsconnectedbysharpcircularcurve,ridingisextremelyuncomfortable.Asthecarapproachesacurve,superelevationbeginsandthevehicleistiltedinward,butthepassengermustremainverticalsincethereisnocentrifugalforcerequiringcompensation.Whenthevehiclereachesthecurve,fullcentrifugalforcedevelopsatonce,andpullstherid
24、eroutwardfromhisverticalposition.Toachieveapositionofequilibriumhemustforcehisbodyfarinward.Astheremainingsuperelevationtakeseffect,furtheradjustmentinpositionisrequired.Thisprocessisrepeatedinreverseorderasthevehicleleavesthecurve.Wheneasementcurvesareintroduced,thechangeinradiusfrominfinityontheta
25、ngenttothatofthecircularcurveiseffectedgraduallysothatcentrifugalv6-2/9forcealsodevelopsgradually.Bycarefulapplicationofsuperelevationalongthespiral,asmoothandgradualapplicationofcentrifugalforcecanbehadandtheroughness(canbe)avoided.approachprtn.方法；途径；接近;vt.接近；vi.靠近tilttltn.倾斜vt.使倾斜；使翘起vi.倾斜；翘起takee
26、ffect生效；起作用easementizm()ntn.缓和；减轻easementcurve缓和曲线farfadj.远的；久远的adv.很；遥远地；到很远的距离；到很深的程度n.远方v6-1/9vIfavehicletravelsathighspeedonacarefullyrestrictedpathmadeupoftangentsconnectedbysharpcircularcurve,ridingisextremelyuncomfortable.vAsthecarapproachesacurve,superelevationbeginsandthevehicleistiltedinwa
27、rd,butthepassengermustremainverticalsincethereisnocentrifugalforcerequiringcompensation.vWhenthevehiclereachesthecurve,fullcentrifugalforcedevelopsatonce,andpullstherideroutwardfromhisverticalposition.Toachieveapositionofequilibriumhemustforcehisbodyfarinward.vAstheremainingsuperelevationtakeseffect
28、,furtheradjustmentinpositionisrequired.v6-2/9vThisprocessisrepeatedinreverseorderasthevehicleleavesthecurve.vWheneasementcurvesareintroduced,thechangeinradiusfrominfinityonthetangenttothatofthecircularcurveiseffectedgraduallysothatcentrifugalforcealsodevelopsgradually.vBycarefulapplicationofsuperele
29、vationalongthespiral,asmoothandgradualapplicationofcentrifugalforcecanbehadandtheroughness(canbe)avoided.Approachprtn.方法；途径；接近vt.接近；着手处理vi.靠近tilttltn.倾斜vt.使倾斜；使翘起vi.倾斜；翘起takeeffect生效；起作用easementizm()ntn.缓和；减轻easementcurve缓和曲线v7/9vEasementcurveshavebeenusedbytherailroadsformanyyears,buttheiradoptionb
30、yhighwayagencieshasbecomeonlyrecently.Thisisunderstandable.Railroadtrainsmustfollowtheprecisealignmentofthetracks,andthediscomfortdescribedherecanbeavoidedonlybyadoptingeasementcurves.Ontheotherhand,themotor-vehicleoperatorisfreetoalterhislateralpositionontheroadandcanprovidehisowneasementcurvesbyst
31、eeringintocircularcurvesgradually.However,thisweavingwithinatrafficlane(butsometimesintootherlane)isdangerous.Properlydesignedeasementcurvesmakeweavingunnecessary.Itislargelyforsafetyreasons,then,thateasementcurveshavebeenwidelyadoptedbyhighwayagencies.vRailroadsn.铁路（railroad的复数）；铁路部门vHighwayAgency公
32、路管理局Agencyn.机构vsteeringstrn.操纵；指导；掌舵v.驾驶；掌舵（steer的ing形式）vweavewivvi.迂回行进vt.使迂回前进vtrafficlane行车道；通车车道v7/9vEasementcurveshavebeenusedbytherailroadsformanyyears,buttheiradoptionbyhighwayagencieshasbecomeonlyrecently.vThisisunderstandable.Railroadtrainsmustfollowtheprecisealignmentofthetracks,andthedisc
33、omfortdescribedherecanbeavoidedonlybyadoptingeasementcurves.vOntheotherhand,themotor-vehicleoperatorisfreetoalterhislateralpositionontheroadandcanprovidehisowneasementcurvesbysteeringintocircularcurvesgradually.vHowever,thisweavingwithinatrafficlane(butsometimesintootherlane)isdangerous.Properlydesi
34、gnedeasementcurvesmakeweavingunnecessary.vItislargelyforsafetyreasons,then,thateasementcurveshavebeenwidelyadoptedbyhighwayagencies.v8/9vForthesameradiuscircularcurve,theadditionofeasementcurvesattheendschangesthelocationofthecurvewithrelationtoitstangents;hencethedecisionregardingtheiruseshouldbema
35、debeforethefinallocationsurvey.ThepointofbeginningofanordinarycircularcurveisusuallylabeledthePC(pointofcurve)orBC(beginningofcurve).ItsendismarkedthePT(pointoftangent)orEC(endofcurve).Forcurvesthatincludeeasements,thecommonnotationis,asstationingincreases:TS(tangenttospiral),SC(spiraltocircularcurv
36、e),CS(circularcurvetospiral),andST(spiraltotangent).v8/9vForthesameradiuscircularcurve,theadditionofeasementcurvesattheendschangesthelocationofthecurvewithrelationtoitstangents;hencethedecisionregardingtheiruseshouldbemadebeforethefinallocationsurvey.vThepointofbeginningofanordinarycircularcurveisus
37、uallylabeledthePC(pointofcurve)orBC(beginningofcurve).ItsendismarkedthePT(pointoftangent)orEC(endofcurve).vForcurvesthatincludeeasements,thecommonnotationis,asstationingincreases:TS(tangenttospiral),SC(spiraltocircularcurve),CS(circularcurvetospiral),andST(spiraltotangent).labelleb()ln.标签；vt.标注；贴标签于
38、notationnte()nn.符号；Stationingn.驻军v.驻扎（station的ing形式）;布点;定位v9/9vOntwo-lanepavementsprovisionofawilderroadwayisadvisableonsharpcurves.Thiswillallowforsuchfactorsas(1)thetendencyfordriverstoshyawayfromthepavementedge,(2)increasedeffectivetransversevehiclewidthbecausethefrontandrearwheelsdonottrack,and(
39、3)addedwidthbecauseoftheslantedpositionofthefrontofthevehicletotheroadwaycenterline.For24-ftroadways,theaddedwidthissosmallthatitcanbeneglected.Onlyfor30mphdesignspeedsandcurvessharperthan22(degree)doestheaddedwidthreach2ft.Fornarrowerpavements,however,wideningassumesimportanceevenonfairlyflatcurves
40、.RecommendedamountsofandproceduresforcurvewideningaregiveninGeometricDesignforHighways.vprovisionprovisionprv()nn.事前准备vadvisabledvazb()ladj.明智的，可取的，适当的vshyawayfrom回避，退缩；躲避；vtransversetrnzvs;trnz-;-ns-n.横断面；贯轴；adj.横向的；横断的；贯轴的vrearwheel后轮；后车轮vvehiclewidth车宽vtracktrkvi.追踪；vt.追踪；通过；循路而行；n.轨道；足迹，踪迹；小道vsl
41、antedsl:ntid,slnt-adj.斜的；有倾向的v.使倾斜（slant的过去式和过去分词）vmph,empi:eitabbr.每小时英里数（milesperhour）vassumesjumvt.承担；假定；采取；v9/9vOntwo-lanepavementsprovisionofawilderroadwayisadvisableonsharpcurves.vThiswillallowforsuchfactorsas(1)thetendencyfordriverstoshyawayfromthepavementedge,(2)increasedeffectivetransversev
42、ehiclewidthbecausethefrontandrearwheelsdonottrack,and(3)addedwidthbecauseoftheslantedpositionofthefrontofthevehicletotheroadwaycenterline.vFor24-ftroadways,theaddedwidthissosmallthatitcanbeneglected.Onlyfor30mphdesignspeedsandcurvessharperthan22(degree)doestheaddedwidthreach2ft.vFornarrowerpavements
43、,however,wideningassumesimportanceevenonfairlyflatcurves.RecommendedamountsofandproceduresforcurvewideningaregiveninGeometricDesignforHighways.vFinishLesson 3 Geometric design of highways vText A Alignment Designvalignment lanm()nt n.队列，线形；v课文A 路线设计vText B Gradesv课文B 坡度vText C Sight Distancev课文C 视距v
44、1/9vTheverticalalignmentoftheroadwayanditseffectonthesafeandeconomicaloperationofthemotorvehicleconstituteoneofthemostimportantfeaturesofroaddesign.Theverticalalignment,whichconsistsofaseriesofstraightlinesconnectedbyverticalparabolicorcircularcurves,isknownasthe“gradeline”.Whenthegradelineisincreas
45、ingfromthehorizontalitisknownasa“plusgrade”,andwhenitisdecreasingfromthehorizontalitisknownasa“minusgrade”.Inanalyzinggradeandgradecontrols,thedesignerusuallystudiestheeffectofchangeingradeonthecenterlineprofile.vNewwordsandexpressionsvGrade坡度Gradecontrol坡度控制Gradeline坡度线，纵坡线Gradelength坡长Gradereducti
46、onMinusgrade下坡降坡Plusgrade上坡升坡Maximumgrade最大纵坡Minimumgrade最小纵坡Sustainedgrade持续坡度Levelgrade平坡Steepgrade陡坡vparabolic,prblkadj.抛物线的Paraboliccurve抛物线vchangein在方面改变v1/9vTheverticalalignmentoftheroadwayanditseffectonthesafeandeconomicaloperationofthemotorvehicleconstituteoneofthemostimportantfeaturesofroad
47、design.vTheverticalalignment,whichconsistsofaseriesofstraightlinesconnectedbyverticalparabolicorcircularcurves,isknownasthe“gradeline”.vWhenthegradelineisincreasingfromthehorizontalitisknownasa“plusgrade”,andwhenitisdecreasingfromthehorizontalitisknownasa“minusgrade”.vInanalyzinggradeandgradecontrol
48、s,thedesignerusuallystudiestheeffectofchangeingradeonthecenterlineprofile.v2/9vIntheestablishmentofagrade,anidealsituationisoneinwhichthecutisbalancedagainstthefillwithoutagreatdealofborroworanexcessofcuttobewasted.Allhaulsshouldbedownhillifpossibleandnottoolong.Thegradeshouldfollowthegeneralterrain
49、andriseandfallinthedirectionoftheexistingdrainage.Inmountainouscountrythegrademaybesettobalanceexcavationagainstembankmentasacluetowardleastoverallcost.Inflatorprairiecountryitwillbeapproximatelyparalleltothegroundsurfacebutsufficientlyaboveittoallowsurfacedrainageand,wherenecessary,topermitthewindt
50、ocleardriftingsnow.Wheretheroadapproachesorfollowsalongstreams,theheightofthegradelinemaybedictatedbytheexpectedleveloffloodwater.Underallconditions,smooth,flowinggradelinesarepreferabletochoppyonesofmanyshortstraightsectionsconnectedwithshortverticalcurves.vbalanceagainst和.保持平衡vHauln.搬运，运土，运程vTerra