l3 geometric design of highways 公路线型设计

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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Lesson3GeometricdesignofhighwaysTextAAlignmentDesignalignment[ə‘laɪnm(ə)nt]n.队列，线形；课文A线路设计TextBGrades课文B坡度TextCSightDistance课文C视距geometric[,dʒɪə’metrɪk]adj.几何学的[1]/[9]Thealignmentofaroadisshownontheplaneviewandisaseriesofstraightlinescall

2、edtangentsconnectedbycircularcurves.Inmodernpracticeitiscommontointerposetransitionorspiralcurvesbetweentangentsandcircularcurves.Tangent[‘tæn(d)ʒ(ə)nt]n.[数]切线，[数]正切adj.切线的，相切的；interpose[ɪntə'pəʊz]vi.干预；插入；transition[træn‘zɪʃ(ə)n;trɑːn-;-’sɪʃ-]n.过渡；转变；circular[

3、‘sɜːkjʊlə]adj.循环的；圆形的；spiral[‘spaɪr(ə)l]n.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，过去分词spiraled/spiralled，现在分词spiraling/spiralling，第三人称单数spirals，副词spirally）spiralcurve螺旋曲线circularcurve圆形曲线[1]/[9]Thealignmentofaroadisshownont

4、heplaneviewandisaseriesofstraightlinescalledtangentsconnectedbycircularcurves.Inmodernpracticeitiscommontointerposetransitionorspiralcurvesbetweentangentsandcircularcurves.翻译？？？[1]/[9]Thealignmentofaroadisshownontheplaneviewandisaseriesofstraightlinescalledtang

5、entsconnectedbycircularcurves.翻译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。Inmodernpracticeitiscommontointerposetransitionorspiralcurvesbetweentangentsandcircularcurves.翻译在现代实践（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。[2]/[9]Alignmentmustbeconsistent.Suddenchangesfromflattosharpcurvesa

6、ndlongtangentsfollowedbysharpcurvesmustbeavoided;otherwise,accidenthazardswillbecreated.Likewise,placingcircularcurvesofdifferentradiiendtoend(compoundcurves)orhavingashorttangentbetweentwocurvesispoorpracticeunlesssuitabletransitionsbetweenthemareprovided.Long

7、,flatcurvesarepreferableatalltimes,astheyarepleasinginappearanceanddecreasepossibilityoffutureobsolescence.However,alignmentwithouttangentisundesirableontwo-laneroadsbecausesomedrivershesitatetopassoncurves.Long,flatcurvesshouldbeusedforsmallchangesindirection,

8、asshortcurvesappearas‘kink’.Alsohorizontalandverticalalignmentmustbeconsideredtogether,notseparately.Forexample,asharphorizontalcurvebeginningnearacrestcancreateaseriousacci