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1、外文文献翻译（含：英文原文及中文译文）文献出处：YHassan.GeometricDesignofHighways[J]AdvancesinTransportationStudies,2016,6(1):31-41.英文原文GeometricDesignofHighwaysYHassanA.AlignmentDesignThealignmentofaroadisshownontheplaneviewandisaseriesofstraightlinescalledtangentsconnectedbycircularc
2、urves.Inmodempracticeitiscommontointerposetransitionorspiralcurvesbetweentangentsandcircularcurves.Thelineshapeshouldbecontinuous,suddenchangesfromflatlinetosmallradiuscurveorsuddenchangeoflonglineendconnectedtosmallradiuscurveshouldbeavoided,otherwiseatrafficac
3、cidentmayoccur.Similarly,arcswithdifferentradiiend-to-end(complexcurves)orshortstraightlinesbetweentwoarcswithdifferentradiiarebadlinesunlessaneasingcurveisinsertedbetweenarcs.Thelong,smoothcurveisalwaysagoodlinebecauseitisbeaut血llylinedandwillnotbeabandonedinth
4、efuture.However,itisnotidealthatthetwo-wayroadlineshapeiscomposedentirelyofcurves,becausesomedriversalwayshesitatetopassthroughcurvedroadsegments.Thelongandslowcurveisusedinthesmallercomers.Ifyouuseashortcurve,youwillsee"kinks."Inaddition,thedesignoftheflatandve
5、rticalsectionsofthelineshouldbeconsideredcomprehensivelyandshouldnotbeonlyone.Nomatterwhich,forexample,whenthestartingpointoftheflatcurveisnearthevertexoftheverticalcurve,serioustrafficaccidentswilloccur.Vehiclesdrivingoncurvedsectionsaresubjectedtocentrifugalfo
6、rce,andtheyneedaforceofthesamemagnitudeintheoppositedirectionduetotheheightandlateralfrictiontooffsetit.Fromtheviewpointofhighwaydesign,thehighorhorizontalfrictioncannotexceedacertainvalue.Them邸imum,thesecontrolvaluesforacertaindesignspeedmaylimitthecurvatureoft
7、hecurve.Ingeneraithecurvatureofac订cularcurveisrepresentedbyitsradius.Forthelineardesign,thecurvatureisoftendescribedbythecurvature,ie,thecentralanglecorrespondingtothe100-footcurve,whichisinverselyproportionaltotheradiusofthecurve.Anormalroadarchissetinastraight
8、sectionoftheroad,andthecurvesectionissettoasuperhigh,andanexcessivelygradualroadsectionmustbesetbetweenthenorn叫sectionandthesuperhighsection.Theusualpracticeistomaint
