美赛a题一等奖论文文档格式.docx
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美赛a题一等奖论文文档格式.docx
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Studyonfreewaytrafficcondition4
1.1AnalysisonthetrafficflowundertheKeepRightExcepttoPassrule4
1.1.1Trafficflowcharacteristicsunderdifferentloadsonthefreeway4
1.1.2Trafficflowcharacteristicsbasedonfreewaylane-changingbehaviors7
1.2AnalysisonsafetyundertheKeepRightExcepttoPassrule11
1.2.1Therelationshipbetweenthetrafficflowandroadsafety11
1.2.2Thecomprehensiveevaluationmodeloffreewaytrafficsafetybasedontrafficflowcharacteristics13
1.3Optimizedtrafficrulesmodel17
1.3.1Trafficrulesontwo-wayfour-lanefreeways17
1.3.2Trafficrulesontwo-waysix-lanefreeways20
1.3.3Trafficrulesontwo-wayeight-lanefreewaysormore21
Problem2:
Analysisontheperformanceoftrafficofdrivingleftandright21
2.1Analysisofphysicalfactorsoftraffic23
2.2Analysisonmentalandphysiologicalfactorsofmen23
2.2.1Reliabilityanalysisonthefieldofviewonthemoveanddrivingsafety24
2.2.2Analysisonthereactionanddistributionoftheleft-handedandright-handed26
2.2.3Analysisonthedrivingfeatures27
Problem3:
AnalysisandoutlookonIntelligentTransportationSystems28
3.1AnalysisonthetrafficflowbasedonITS30
3.1.1Modelsonthebehaviourreliabilityandtrafficflow30
3.2AnalysisonthetransportationabilitybasedonITS31
3.3StudyonthesecurityofITS31
3.3.1IndexanalysisofITS32
3.4VisionforintegrationofIntelligentTransportationSystems[13]33
3.4.1Improvementofsecuritycoordinatedbyvehiclesandroads33
3.4.2Increasingtransportationmanagementlevelusinginformationtechnology.33
3.4.3Coordinationoftransportationsanditsutilityimprovementbasedoninformationsharing33
Reference35
Background
Freewayaredesignedfortwo-dimension,multilaneuseforautomobileswhichcantakefullycontrolofallvehicles,adaptingto120km/horhigherspeed.Ithasstrongcapacityoftransportation.Forinstance,thetotalmileageofthefreewayinAmericaisonly1%ofthewholemileageofthehighway,butitundertakesmorethan20%transportationofAmerica.
ItisquiteinterestingtowhendiggingintotheoriginoftheKeepRightExcepttoPasstrafficrule.InmedievalEurope,thereisaspecialstratum,thatis,knight.Accordingtotheirhabit,theyridehorse,withswordintheirrighthands,shieldandreinintheirlefthands.Iftheyrideontheleftside,theycanattackenemies’weakpoints.Astimegoesby,peopleinEnglanddriveontheleftside.AsknightsinEngland,Japanhaswarriors.Inordertoprotectthemselves,theywalkontheleftsideoftheroad.WhentheFrenchrevolutionarrived,theFrenchstartedtogoontherightside.Powerpoliticshavecloserelationshipbetweenthedrivingside.BritishCommonwealthandcoloniesofEnglandstilldriveontheleftside.ColoniesofFrancedriveontheright.Untilthesecondworldwar,becauseoftheassistingcarsfromAmericadriveontheright,ChinastarttocomplywiththeKeepRightExcepttoPasstrafficrule.ThetrafficofPakistanisquiteuniqueandinteresting,camelsgoalongtheleftanditisquitedifficulttochange.Peoplehavetofollowtheirrules.
Thisincreaseinroadtransportbringsbenefitstosocietyintermsofmobilityandaccessibility,italsohoweverhascosts.Thecostsincludenotonlythedirectcostofprovidingtransportservicessuchasinfrastructure,personnel,equipmentcostsbutalsothevariousindirectcostsintermsoftheimpactontheenvironment,mostnotablynoiseandairpollution;
traveldelayduetotrafficcongestion;
andthelossoflifeandpropertydamageasaresultofroadaccidents.Thegrowingnumberoftrafficaccidentshavedirecteffectsonourcountry’snationaleconomicdevelopment,threateningpeople’slifeandpropertysecurity,increasingthepressuretothesecurityandstabilityofthewholesociety.
Studyonfreewaytrafficcondition
1.1AnalysisonthetrafficflowundertheKeepRightExcepttoPassrule
1.1.1Trafficflowcharacteristicsunderdifferentloadsonthefreeway
Inordertodiscusstrafficflow,firstlyofall,weshouldknowexactlywhattrafficflowis.Wefindthattrafficflowcanbedescribedbythreemainparameterstheoretically:
flow,speedanddensity.Speedanddensitycanreflectthequalityofserviceacquiredfromfreeway.However,flowcandescribethedemandoftrafficfacilities.Theparametersareindependentrandomvariablesandthedistributionoftrafficflowobeysthestatisticallaws.Tomakeitclearer,thetrafficflowfollowsPoissondistribution[1].
Where:
denotesthepossibilityof
carsinacertaintimeperiod
denotesthefixedtimeperiod(
)
denotesthenumberofcarsperunitoftime,
denotestheaveragecarnumberinperiod
1.1.1.1Therelationshipbetweenspeedanddensity
Whendrivingontheroad,weallexperiencethatthelowerthedensityis,thefasterthecargoes.Whenthedensitygoeshigher,thenumberofcarsincrease.Sothatdriversareforcedtoreducespeed.Whenthetrafficisgettingheavier,carsareslowerandtheroadbecomesmorecrowdeduntilcongestionhappens.
In1933,Greenshieldsputforwardlinearmodelbetweenspeedanddensity[1].
indicatesacorrelationconstantwhichcanbeacquiredbyfittingspecificdata.
indicatesthenavigatespeedwhichisconstrainedbyroadconditionsonly
indicatesthecongestiondensity.
Themodelisintuitiveandpractical,fittingwellwithmeasureddata.When
canreachnavigatespeed
whichisthehighestspeedtheoretically.
1.1.1.2Therelationshipbetweenflowanddensity
TherelationshipcanbededucedfromGreenshieldsmodel[1].
Theformulaisapproximatelyaquadraticrelationshipwhichcanbedescribedbyparabola-likecurve.
Figure1.Therelationshipbetweentrafficflowandvehicledensity
Whenthedensityiszero,theflowiszero.Sothecurvegoesthroughthecoordinateorigin.Theflowincreasesasdensityincreasesuntilitreachesthemaximumtransportationabilityoftheroad,whichis
inFigure1.Thecorrespondingdensityisthebetterdensity
.Frompoint
on,asvehicledensityincreases,speedandflowgodownuntilitreachescongestiondensity
.Atthatpoint,thespeedandflowturnzero.Depictradiusvectorfromthecoordinateorigintothecurve.Theslopeofthevectorindicatesthemeanspeedofthecertainpointonthecurve.Theradiusvectorthroughpoint
istangenttothecurve,theslopeofwhichisthenavigatespeed
.Fordensitysmallerthan
thetrafficisnotcrowded.However,fordensitybiggerthan
thetrafficiscrowded.
Let
wecanget
correspondingto
asfollows.
Forinstance,
.
1.1.1.3Therelationshipbetweenspeedandflow.
Wecanseefromtheformulathat,therelationcurvebetweenspeedandflowapproximatelyfollowsaparabolacurve.
Figure2.Therelationshipbetweenspeedandtrafficflow
Whenthedensityiszero,thespeedofthesmoothtrafficflowcanreachthehighestspeed
.Meanwhiletheflowiszero.Whenthedensityreaches
thespeediszero,soastheflow.Sothatthecurvegoesthroughthecoordinateorigin.
From
wedepictalineperpendiculartotheaxis.Theleftpartofthelineindicateslighttraffic,inwhichspeeddecreaseswiththeincreaseofflowuntilthemaximumflow
.Therightpartindicatesheavytraffic.Theflowandspeedgodowntogether.
Conclusion
Basedonthethreeparameters,wegetfollowingconclusions.
●Whenthedensityissmall,vehicle
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