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1、路桥工程专业英语第四课第四课FreewayanditsAccessoryFacilities高速公路及其附属设施Text:FreewayDesignReadingMaterial:FreewayAccessoryFacilitiesTextFreewayDesignFreewayarethehighestformofarterialsandhavefullaccesscontrol.Thefullcontrolofaccessisneedforprioritizingtheneedforthroughtrafficoverdirectaccess.
2、Afreeway'sprimaryfunctionistoprovidemobility,highoperatingspeed,andlevelofservice,whilelandaccessislimited.Accessconnections,wheredeemednecessary,areprovidedthroughgradeseparatedinterchanges.Themajoradvantagesofaccesscontrolledfreewaysarehighcapacityofthefacility,highoperating
3、speeds,efficiencyofthefacility,andsafetytoallhighwayusers.Themajordifferencesbetweenfreewayandotherarterialsincludethefollowingelements:gradeseparationsatcrossroadsandstreets;thegradeseparatedcrossroadconnectionsbetweenthefreewayandcrossroadareaccomplishedthroughexitandentranc
4、eramps;andfullcontrolofaccess.Expresswayscanbedesignedwithbothfreewayandnon-freewaydesignelements.Theuseofjughandlestyleinterchangesanduseofrightturnchannelizationisnotconsideredfreewaydesign,butcanbeusedinexpresswaydesign.Urbanfreewaysgenerallyhavemoretravellanesandcarrymoret
5、rafficthanruralfreeways.Urbanfreewayscanbeeigherdepressed,elevated,atgroundlevel,oracombinationoftheabove.Urbanfreewaysusuallyhaveanarrowermedianthanruralfreewaysandtendtohavemoreconnectionsthanruralfreeways.Ruralfreewaysaregenerallysimilarinconcepttourbanfreeways,exceptthatth
6、ehorizontalandverticalalignmentsaremoreconservativeindesign.Thislevelofdesignisnormallyassociatedwithhigherdesignspeedsandgreateraccessibilitytorightofway.Duetotheruralnature,rightofwayistypicallymoreavailableandlessexpensive.Thisallowsforawidermedianwhichimprovesthesafetyofth
7、efacility.Inadditiontotheincreaseinsafetyofaruralfreeway,thehigherdesignspeedsinaruralsettingallowforgreatercapacity,ahigherlevelofmobility,andpotenciallyareducedneedformultiplelanes.Ruralfreewaysarenormallymorecomfortablefromadriverperspective,andgenerallyhavelowermaintenance
8、costs.Thesectionsbelowdiscussthedifferentdesignelementsofurba
