IntelligentTransportationSystemsforImprovingTrafficEnergyEfficiencyandReducingGHGEmissionsfromRoadways

November 2015

AWhitePaperfromtheNationalCenterforSustainableTransportation

MatthewBarth,GuoyuanWu,andKanokBoriboonsomsin

CenterforEnvironmentalResearchandTechnology

BournsCollegeofEngineering

UniversityofCalifornia,Riverside

U.S.DepartmentofTransportation(USDOT)DisclaimerThecontentsofthisreportreflecttheviewsoftheauthors,whoareresponsibleforthefactsandtheaccuracyoftheinformationpresentedherein.ThisdocumentisdisseminatedunderthesponsorshipoftheUnitedStatesDepartmentofTransportation’sUniversityTransportationCentersprogram,intheinterestofinformationexchange.TheU.S.Governmentassumesnoliabilityforthecontentsorusethereof.AcknowledgmentsThisstudywasfundedbyagrantfromtheNationalCenterforSustainableTransportation(NCST),supportedbytheU.S.DepartmentofTransportation(U.S.DOT)throughtheUniversityTransportationCentersprogram.TheauthorwouldliketothanktheNCSTfortheirsupportofuniversity-basedresearchintransportation,andespeciallyforthefundingprovidedinsupportofthisproject.Theauthorswouldalsoliketoacknowledgeothersourcesforvariousmaterials,bothinresearchsupportandfunding,includingtheCaliforniaDepartmentofTransportation,andtheU.S.DOT’sApplicationsfortheEnvironment:Real-timeInformationSynthesis(AERIS)connectedvehicleresearchprogram.Lastly,theauthorswouldalsoliketoacknowledgeXueweiQioftheUniversityofCalifornia,Riversideforhisassistanceingatheringinformationusedinthiswhitepaper. AbouttheNationalCenterforSustainableTransportationTheNationalCenterforSustainableTransportationisaconsortiumofleadinguniversitiescommittedtoadvancinganenvironmentallysustainabletransportationsystemthroughcutting-edgeresearch,directpolicyengagement,andeducationofourfutureleaders.Consortiummembersinclude:UniversityofCalifornia,Davis;UniversityofCalifornia,Riverside;UniversityofSouthernCalifornia;CaliforniaStateUniversity,LongBeach;GeorgiaInstituteofTechnology;andUniversityofVermont.Moreinformationcanbefoundat:ncst.ucdavis.edu.

TABLEOFCONTENTSEXECUTIVESUMMARY....................................................................................................................1

Introduction....................................................................................................................................3

ITSandTheirImpactonTrafficEnergyandEmissions...................................................................3

VehicleSystems..........................................................................................................................3

TrafficManagementSystems.....................................................................................................4

TravelInformationSystems........................................................................................................5

ImpactofITSonTrafficEnergyandEmissions...........................................................................5

RecentEnvironmentalITSResearchProgramsintheUnitedStates..............................................6

Eco-TrafficSignalOperations.....................................................................................................7

Eco-LanesOperations.................................................................................................................9

RecentEnvironmentalITSResearchProgramsintheEuropeanUnion.......................................10

VehicleSystems........................................................................................................................10

TrafficManagementSystems...................................................................................................11

TravelInformationSystems......................................................................................................11

ResearchNeeds............................................................................................................................12

Environment-Mobility-SafetyNexus........................................................................................12

InducedTravelDemand...........................................................................................................12

Conclusions...................................................................................................................................12

References....................................................................................................................................14

1

IntelligentTransportationSystemsforImprovingTrafficEnergyEfficiencyandReducingGHGEmissionsfromRoadways

EXECUTIVESUMMARYThefieldofIntelligentTransportationSystems(ITS)haswitnessedsignificantlyincreasedactivityinrecentyears,withtheapplicationofmoderncontrol,communications,andinformationtechnologiestovehiclesandroadwayinfrastructure.Ingeneral,ITScanbecategorizedintothreemajortargetareas:VehicleSystems,TrafficManagementSystems,andTravelInformationSystems.TheprimaryobjectivesofITShavebeenfocusedprimarilyonimprovingsafetyandincreasingmobilityandassociatedtransportationefficiency.Inaddition,itisnowwellknownthatITStechnologycanbeusedtoreducetransportation-relatedenvironmentalimpacts.Theseenvironmentalimpactsincludepollutantemissionsthatleadtopoorairquality,aswellasenergyconsumptionandgreenhousegas(GHG)emissions.Overtheyears,wehaveseenmanyITSprogramsfocusingonsafetyandmobilityalsohavingsignificantenvironmentalbenefits.Thesebenefitsrangewidelyduetoanumberofvariablessuchastypeofapplication,technologyused,andpre-existingconditionbeforedeployment.Inrecentyears,anumberofITSprogramshaveemergedthatarespecificallydesignedtominimizetheenvironmentalimpactsoftransportation.Manyoftheseenvironmental-ITSprogramstakeadvantageofthe“connectedvehicle”technologythatenablesvehiclestocommunicatewitheachotheraswellaswithroadwayinfrastructure,andviceversa.Theseenvironmental-ITSprogramstypicallyshowenergyandemissionsreductionsontheorderof5%to15%.

KeyFindingsManyITSprogramsfocusingonsafetyandmobilityalsoprovidesignificantenvironmentalbenefits.Thesebenefitsrangewidelyduetoanumberofvariablessuchastypeofapplication,technologyused,andpre-existingconditionbeforedeployment.Recentlyemergedenvironmental-ITSprogramsthatarespecificallydesignedtominimizetheenvironmentalimpactsoftransportationhavebeenshowntoreduceenergyandemissionsontheorderof5%to15%.Currentenvironmental-ITSresearchprogramsintheUnitedStatesandtheEuropeanUnionarefocusedondevelopingandtestingapplicationsthattakeadvantageof“connectedvehicle”technology,whichenablesvehiclestocommunicatewitheachotheraswellaswithroadwayinfrastructure,andviceversa.Researchisneededtoimproveourunderstandingoftheconnectionbetweenenvironment,mobility,andsafetyperformanceofanyITSprograms.ResearchisalsoneededtoquantifythepotentialinduceddemandeffectsofITSprogramdeployment.

2

Mostoftheenvironmental-ITSprogramsareadditive,thereforegreaterbenefitsmaybeachievedwhenamultitudeoftheseprogramsareputintoplace.Ontheotherhand,themobilityandsafetyimpactsofenvironmental-ITSprogramsarenotcurrentlywellunderstood.Asmoreoftheseprogramsaredeployed,comprehensiveimpactassessmentsoftheirenvironmental,mobility,andsafetyperformancesareneeded.WhenplanningthedeploymentofITSprogramsthatwillimprovetrafficflowandreducecongestion,itisimportanttoalsoconsideranypotentialinduceddemandeffects,whichmayresultinanoverallincreaseinvehiclemilestraveled(VMT)aftertheITSprogramshavebeendeployedforacertainperiodoftime.SuchincreaseintheamountoftravelisundesirableasitmaywashoutthemobilityandenvironmentalbenefitsoftheITSprograms.Itmaybethattocounteracttheseeffects,theITSprogramsmayhavetobecoupledwithsomespecifictraveldemandmanagementmeasuressuchaspricing.

3

IntroductionDuetotheirpotentialtoimproveroadwaysafety,reducetrafficcongestion,andenhancethemobilityofpeopleandgoods,IntelligentTransportationSystems(ITS)havegeneratedconsiderableenthusiasminthetransportationcommunity.Inadditiontoenhancingsafetyandmobility,wearenowseeingthatITScanplayamajorroleinreducingcriteriapollutantandgreenhousegas(GHG)emissions,andenergyconsumption.Itiscommonlyunderstoodthatthetransportationsectorisresponsiblefornearlyone-thirdofGHGemissions(see,e.g.,(1)).InordertoreducetheseGHGcontributions,muchofthefocushasbeenputon:1)improvingoverallvehiclefueleconomy(e.g.,usingmoreefficientinnovativedrivetrains,reducingweightwhilemaintainingsafety);2)usinglesscarbon-intensivefuels(e.g.,ethanol,electricity);and3)managingtraveldemand(e.g.,roadwaytolling)andshiftingtraveltonon-motorizedmodes.Inaddition,wearenowseeingthatITScanbeappliedasafourthkeycomponent,namelytoimprovetheefficienciesoftransportationsystemoperations,therebyreducingoverallGHGemissions.

ITSandTheirImpactonTrafficEnergyandEmissionsITSconsistsofawidevarietyoftechnologiesandapplications,asdescribedintheU.S.NationalIntelligentTransportationSystemArchitecture(2).Ingeneral,ITScanbecategorizedintothreemajorareas:VehicleSystems,TrafficManagementSystems,andTravelInformationSystems.TheseareasandtheirpotentialforreducingGHGemissionsarebrieflyintroducedbelow.

VehicleSystemsVehiclesarenowtakingadvantageofmoderncontrolsystems,fasteron-boardprocessors,andwirelesscommunicationstoprovidefeaturesthatgreatlyimprovetheirperformance.Examplesofemergingvehiclesystemsincludethefollowing:LongitudinalAssistanceSystemsaretypicallyusedtopreventfront-endandrear-endcollisions.On-boardradar,LiDAR,andcomputervisiontechnologymonitorheadwaysbetweenvehicles,andbyprovidingfeedbacktothevehicle’sbrakingsystem,canhelpreducecollisions.ThesesensorsarealsobeingusedforAdaptiveCruiseControl(ACC)systemsthatnotonlyallowadrivertoselectadesiredspeed,butalsoallowsettingthefollowingdistance.Withtheadditionofwirelesscommunicationcapabilities,ACCcanevolveintoCooperativeAdaptiveCruiseControl(CACC)wherevehiclescommunicatewitheachotherto“cooperatively”managefollowingdistance,braking,accelerating,andmore.CACCisnowemergingasapopularareaofresearch.LateralAssistanceSystemsaredesignedtoimprovetheperformanceofvehiclesduringlanechanges,merges,oranykindofturningmovement.Computervisiontechnologyandothersensorscoupledwithwirelesscommunicationsarebeingdeployedtoprovidelanedeparturewarningsandtowarndriversofpendinglateralcollisions.

4

Bothlongitudinalandlateralcontrolsystemsarenowleadingusdownthepathtowardspartialandfullautomation,wherevehicleswillautomaticallydrivethemselveswithlittleinputfromthedrivers.WirelessCommunicationsSystemsarenowbeingdeployedinvehiclesinanumberofdifferentways.Cellularcommunicationtechnologyisalreadyplayingalargeroleinfleetmanagementapplicationsandvehiclemonitoring.Inaddition,DedicatedShortRangeCommunication(DSRC)radioswilllikelybedeployedtoenablevehicle-to-vehicle(V2V),vehicle-to-infrastructure(V2I)andinfrastructure-to-vehicle(I2V)applicationsthatareprimarilyfocusedonimprovingsafety.However,mobilityandenvironmentalapplicationswillalsolikelyemergethattakeadvantageofthis“connectedvehicle”technology.

TrafficManagementSystemsOverthelastseveraldecades,thetotalamountofdriving,asmeasuredinVMT,hasgrownsignificantly,contributingtosevereroadwaycongestioninmanyurbanareas.Buildingadditionalinfrastructuretohandletheincreaseintraveldemandisnotalwayspossible.However,anumberofITS-basedTrafficManagementSystemsolutionscanhelpmitigatecongestion,includingthefollowing:TrafficMonitoringSystemsareimprovingwithbettersensortechnology,morereliablecommunicationchannels,andmoreadvancedinformationprocessingcapability.Inadditiontoprovidingtransportationmanagerswithbetterreal-timeinformation,newdataprocessingtechniquesarebeingdevelopedtoestimatetrafficflow,density,andspeed,aswellasothermicroscopictrafficparameters.Thisreal-timetrafficinformationcanbeusedforbettertrafficsystemmanagementandforindividualdriverschoosingalternativeroutes,resultinginreducedcongestion.TrafficIncidentManagementtechniquesareimportanttoolsforearlydetectionandrapidremovalofincidents(i.e.,accidents,disabledvehicles,etc.),sothatnormaltrafficoperationsrecoverasquicklyaspossible.IntegratedCorridorManagementtechniques,suchasinnovativerampmeteringforfreewayaccessramps,andadvancedsignaltimingalgorithmsonarterialnetworks,worktogethertohelpkeeptrafficflowingassmoothlyaspossiblethroughthecorridor,greatlyreducingtheamountofidling.TravelDemandManagementisanothercriticalelementoftrafficmanagement.Byreducingthenumberofvehiclesonacongestedroadwayorspreadingoutthepeakoftrafficvolumethroughpricingandothertechniques,trafficflowwillimprove,resultinginlowerGHGemissions.

5

Theoverarchinggoaloftrafficmanagementistotakefulladvantageofcapacitiesofexistingroadwayinfrastructure,thuskeepingtrafficflowingsmoothlyatmoderatespeeds.Assuch,thiswillhavealargeimpactinreducingenergyconsumptionandGHGemissions.Trafficmanagementsystemstrategiesgoevenfurtherbyreducingthenumberofvehiclesinthetransportationsystem,therebyreducingthetotalcontributionsofGHGemissions.

TravelInformationSystemsTomakethingsmoreconvenienttodrivers,awidevarietyofinformationsystemsfortravelershaverecentlyevolved.Examplesofthistechnologyincludethefollowing:RouteGuidanceSystemshavegreatlyimprovedinrecentyears.Theyincludeon-board,off-board,andsmartphone-basedsystems.Thesenavigationsystemsnowusegeographicandreal-timetrafficinformationandcanselectoptimalroutesinaroadwaynetworkfromspecificoriginstospecificdestinations.Thesesystemsattempttominimizesomecriteria,suchastraveltime,traveldistance,orevenGHGemissions.Geo-LocationSystemsaretypicallycoupledwithrouteguidancesystemstoallowuserstofindspecificlocations,cuttingdownonexcessivedriving(e.g.,searchingforagasolinefillingstation,openparkingspace,etc.).ElectronicPaymentSystemsarebecomingincreasinglyprevalent.Theyenablepaymentoftollsandfeeswithoutstoppingthevehicletocompletethefinancialtransaction.AllofthesesystemsaddconvenienceforthetravelerwhilereducingGHGemissions.Asdescribedabove,arouteguidancesystemwillcutbackonunnecessarytravelthatmayoccurwhenadrivergetslostorchoosesalong,out-of-the-waypath.En-routedriverinformationcanresultinreducedGHGemissionsassociatedwithdrivingaround,searchingforthesespecificgoals.Electronicpaymentsystemseliminatetheneedforadrivertodeceleratethevehicle,idlewhileamanualtransactiontakesplace,thenacceleratethevehiclebacktoadesiredspeed.Ifthispaymentcanoccurwithoutslowingdown,GHGemissionsarereduced.

ImpactofITSonTrafficEnergyandEmissionsAlloftheITSareasdescribedabovehavethepotentialforindirectlyreducingGHGemissionsthroughimprovementsinsafety,mobility,anddriverconvenience.TheactualGHGemissionreductionswillvarysignificantly,dependingonmanyfactors,includingvehiclefleetmix,trafficvolumeanddynamics,andthetypeofroadwaynetworkandinfrastructure.AvarietyoftheseITSapplicationshavebeendesignedandmodeled,andseveralhavebeenpilotedandimplementedindifferentlocations.Inordertodeterminetheoveralleffectivenessoftheseapplications,differentperformancemeasuresareestimated–usuallymobilitymeasuressuchasimprovementsinaveragetraveltimeorreductionsinnetworkdelay.Insomecases,environmentalfactorsarealsoestimated.Onestraightforwardmethodistomonitorthechangesinaveragetraveltimes(andthereforeaveragespeeds),normalizedbythetotalamountoftraffic.Ingeneral,ifoveralltrafficconditionsmovefromacongestedregime(e.g.,

6

averagespeedsbelow30mph)toalesscongestedregime(speedsgreaterthan30mph),thenemissionreductionspervehiclecanbeestimatedusingspeed-emissionfactorcurves,suchasFigure3of(3).Asanexample,trafficsmoothingtechniqueshavebeenshownin(4)toresultina10%to20%CO2reduction.InadditiontotheITSapplicationsdescribedabove,anumberofITSresearchprogramshaveemergedthathavebeenspecificallydesignedtominimizetransportationGHGemissions.ThenextsectionofthiswhitepaperdescribesseveraloftheserecentITSprogramsthataretargetingtheenergyandenvironmentalimpactsoftransportation.

RecentEnvironmentalITSResearchProgramsintheUnitedStatesInthelastdecade,theU.S.DepartmentofTransportation(U.S.DOT)hasinitiatedavarietyofenvironmentallyfocusedITSresearchprograms.ManyofthesearepartoftheFederalHighwayAdministrationExploratoryAdvancedResearchprogram(FHWAEAR,see(5)).Asanexample,intheITSvehiclesystemsarea,researchersattheUniversityofCalifornia,BerkeleyhaveinvestigatedbothACCandCACCandtheirimpactsonmobilityandtheenvironment(6).Furthermore,asanexampleintheareaoftrafficmanagementsystems,thereisanongoingEARprojectonAdvancedTrafficSignalControlAlgorithms,whereseveralalgorithmshavebeendevelopedspecificallyforreducingenergyuseandemissions(see,e.g.,(7)).ResultsfromthesestudiesshowGHGemissionreductionsintherangeof5%to10%.InadditiontotheEARprogram,theU.S.DOThasamajorUniversityTransportationCentersprogram(UTC,see(8)),whereuniversityfaculty,staffandstudentsacrosstheU.S.workonanumberofadvancedtransportationresearchprojects.AnumberofUTCsfocusonsustainability,andseveralofthoseareinvestigatingtheenvironmentalimpactsofITS(see,e.g.,(9)and(10)).Someexampleprojectsfromthesecentersincludeexaminingeco-drivingtechniquesandfreightsignalpriorityforheavy-dutyvehicles(typically5%to8%reductions,seee.g.,(11)),andhowvariablespeedlimitscanbeusedtoreducetransportationenergyconsumptionandimprovevehiclemobility(12).Asanothermajoreffort,theU.S.DOThasalong-termresearchprograminconnectedvehicles.OneofthefoundationalelementsoftheconnectedvehicleresearcheffortintheenvironmentareaistheApplicationsfortheEnvironment:Real-timeInformationSynthesis(AERIS)program(13).Usingvehicle-to-vehicle(V2V),vehicle-to-infrastructure(V2I)andinfrastructure-to-vehicle(I2V)communications,thegoaloftheAERISprogramistodesignITSapplicationsthataimtoreduceenergyconsumptionandemissions.SeveralAERISoperationalconceptshavebeendeveloped,including:1)Eco-SignalOperations;2)Eco-Lanes;3)DynamicLowEmissionsZones;4)SupportforAlternativeFuelVehicle(AFV)Operations;5)Eco-TravelerInformationand6)Eco-IntegratedCorridorManagement(ICM).

7

EarlyintheAERISprogram,severalexploratoryresearchprojectsconductedbyanumberofU.S.researchersinvestigatednewconceptsacrossthedifferentareasofITS,includingthefollowing:

VehicleSystems• DevelopingandEvaluatingIntelligentEco-DriveApplications,carriedoutbyresearchers

atVirginiaTech(14).Thisprojectfocusedonthedevelopmentofaneco-ACCsystemandevaluatedthenetwork-wideimpactsofsuchsystemsfordifferentlevelsofmarketpenetrationandnetworkconfigurations.ResultsshowedGHGemissionreductionsupto49%.

• Assessment,Fusion,andModelingofCommercialVehicleEngineControlUnitData,carriedoutbyCalmarTelematics(withUCRiverside)(15).Thisprojectinvestigatedtheuseofreal-time,onboarddatatocalculateenvironmentalperformancemeasuresbasedpartlyupontheteam’sComprehensiveModalEmissionsModel(CMEM).

TrafficManagementSystems• Eco-SpeedControlUsingV2IcommunicationsalsocarriedoutbyVirginiaTech(14).In

thisproject,innovativeeco-adaptivesignalcontrolalgorithmsweredevelopedandtested.Thesesystemsweremodeledusingtrafficsimulationsoftwareandtestedfordifferentroadwayconfigurations.

• Eco-FriendlyIntelligentTransportationSystems(ECO-ITS),carriedoutbyUCRiverside(16).ThisprojectbuiltonpreviousECO-ITSresearchinpredictingsecond-by-secondfuelconsumptionandtailpipeemissionsfordifferentenvironmental-ITSapplicationsandstrategies,suchasadvancedtrafficsignalization.

TravelInformationSystems• AnEvaluationofLikelyEnvironmentalBenefitsofLowestFuelConsumptionRoute

GuidanceintheBuffalo-NiagaraMetropolitanArea,carriedoutbytheUniversityatBuffalo(17).Thisstudyassessedthelikelyenvironmentalbenefitsofanewapplicationforanenvironmentallyoptimizedrouteguidancesystemformedium-sizedmetropolitanareas.ResultsshowedGHGemissionreductionsintherangeof5%to10%.

Aftertheseinitialexploratoryprojects,theAERISoperationalconceptswerefurtherdevelopedanddefined.ThemainAERISapplicationsthatwereevaluatedindetailaretheEco-TrafficSignalOperationalconcept,includingtheapplicationsofEco-ApproachandDepartureatSignalizedIntersections,Eco-TrafficSignalTiming,andEco-TrafficSignalPriority,aswellastheEco-LanesOperationalconcept,whichincludestheapplicationsofEco-SpeedHarmonizationandEco-CooperativeAdaptiveCruiseControl.Theseapplicationsaredescribedinfurtherdetailbelow.

Eco-TrafficSignalOperationsTherehasbeenagooddealofresearchineco-trafficsignaloperationsaroundtheworld.TheseoperationsuseITStechnologiestodecreasefuelconsumptionandGHGemissionsonarterialroadwaysbyreducingidling,thenumberofstops,andunnecessaryaccelerationsand

8

decelerationsatsignalizedintersections.Priortotheemergenceofconnectedvehicles,eco-trafficsignaloperationswereprimarilyfocusedonsynchronizingtrafficsignalstoimprovetrafficflow,therebyreducingGHGemissions.BytakingadvantageofV2I/I2Vcommunications,anumberofothersignalizationstrategiesemerge,threeofwhicharedescribedbelow.Eco-ApproachandDepartureatSignalizedIntersections—Thisapplicationuseswirelessdatacommunicationssentfromthetrafficsignalcontrollertoconnectedvehiclestoencourage“green”approachestosignalizedintersections.ThisincludesbroadcastingSignalPhaseandTiming(SPaT)dataandaGeographicInformationDescription(GID)orMAPdata.Vehiclestatusmessages,sentfromnearbyvehiclesusingV2Vcommunications,arealsoconsideredbytheapplication.Uponreceivingthisinformation,anon-boardprocessorcanthencalculateanoptimalspeedtrajectorytoapproach,passthrough,anddepartfromasignalizedintersection.Thisspeedtrajectorycanbeprovidedasadvicetothedriverthroughahuman-machineinterface,ordirectlytothevehicle’slongitudinalcontroller(suchastheACCsystem).Thegeneralstrategyistohavethevehiclechangeitsspeedtopasstheupcomingtrafficsignalongreenortodeceleratetoastopinthemosteco-friendlymanner.Thisapplicationalsoconsidersavehicle’saccelerationasitdepartsfromasignalizedintersectionandenginestart-stoptechnologyasavehicleisstoppedatatrafficsignal.Intermsofresults,theAERISprogramhasshownthatthereisa2%to7%energysavingsforallvehiclesandthattheapplicationislesseffectivewhenthecorridoriscongested(see,e.g.,(18),(19)).Eco-TrafficSignalTiming—Thisapplicationissimilartocurrentadaptivetrafficsignalsystems;however,theapplication’sobjectiveistooptimizetrafficsignalsfortheenvironment.Theapplicationcollectsdatafromvehicles,suchasvehiclelocation,speed,GHGandotheremissionsusingconnectedvehicletechnologies.Itthenprocessesthesedatatodevelopsignaltimingstrategiesthatarefocusedonreducingfuelconsumptionandoverallemissionsatanintersection,alongacorridor,orforaregion.Theapplicationevaluatestrafficandenvironmentalparametersateachintersectioninrealtimeandadaptssothatthetrafficnetworkisoptimizedusingavailablegreentimetoservetheactualtrafficdemandswhileminimizingtheenvironmentalimpact.Intermsofresults,theAERISprogramhasshownthatthereisa1%to5.5%energysavingsandthattheapplicationiseffectiveinmostconditionsotherthanfullsaturation(20).Eco-TrafficSignalPriority—Thisapplicationallowseithertransitorfreightvehiclesapproachingasignalizedintersectiontorequestsignalpriorities.Thisapplicationconsidersthevehicle’slocation,speed,vehicletype(e.g.,AlternativeFuelVehicles)andassociatedGHGandotheremissionstodeterminewhetherpriorityshouldbegranted.Informationcollectedfromvehiclesapproachingtheintersection,suchasatransitvehicle’sadherencetoitsschedule,orthenumberofpassengersonthetransitvehiclemayalsobeconsideredingrantingpriority.Ifpriorityisgranted,thetrafficsignalwouldattempttoholdthegreenorterminatetheredontheapproachtofacilitatethetransit/freightvehiclepassingthroughtheintersectionwithoutstopping.Thisapplicationdoesnotconsidersignalpreemption,whichisreservedfor

9

emergencyresponsevehicles.Intermsofresults,theAERISprogramhasshownthatthereisa1%to4%energysavingsforallfreightvehiclesanda1%to2%savingsfortransitvehicles(20).

Eco-LanesOperationsThisconceptusesconnectedvehicletechnologiestodecreasevehiclefuelconsumptionandemissionsbyreducingcongestionandunnecessaryaccelerations/decelerations,improvingtrafficflow,andencouraginggreenerdrivingbehavior.Itisenvisionedthatthiscouldoccureitheronasinglelaneoracrossmultiplelanesonafreeway.ThisEco-Laneconceptcanconsistofanumberofdifferentapplicationsthatarespecificallysetupforafreewayscenario:Eco-LanesManagement—Thisapplicationsupportstheoperationofdynamiceco-lanes,includingestablishingqualificationsforenteringthelanes,definingactivationperiodsorgeo-fencingtheeco-lanes’boundaries.Eco-SpeedHarmonization—TheEco-SpeedHarmonizationapplicationassistsinsmoothingtrafficflow,reducingunnecessarystopsandstarts,andmaintainingconsistentspeeds,thusreducingfuelconsumption,GHGs,andotheremissionsontheroadway.Thiscanbeaccomplishedtypicallythroughvariablespeedlimits.Eco-CooperativeAdaptiveCruiseControl—TheEco-CooperativeAdaptiveCruiseControlapplicationallowsindividualdriverstooptintoapplicationsthattakeadvantageofadaptivecruisecontrolcapabilitiesalongwithV2Vcommunicationsdesignedtominimizevehicleaccelerationsanddecelerationsforthebenefitofreducingfuelconsumptionandvehicleemissions.Eco-RampMetering—TheEco-RampMeteringapplicationdeterminesthemostenvironmentallyefficientoperationoftrafficsignalsatfreewayon-rampstomanagetherateofvehiclesenteringafreeway.ConnectedEco-Driving—TheConnectedEco-Drivingapplicationprovidescustomizedreal-timedrivingadvicetodriverssothattheycanadjusttheirdrivingbehavior(e.g.,speedoftravel,accelerationanddecelerationrates)tosavefuelandreduceemissions.Multi-ModalTravelerInformation—TheMulti-ModalTravelerInformationapplicationprovidespre-tripanden-routemultimodaltravelerinformationtoencourageenvironmentallyfriendlytransportationchoices.IntheUnitedStates,theAERISprogram’sEco-Lanesconceptmodelingwasfocusedonlyontheeco-speedharmonizationandeco-cooperativeadaptivecruisecontrolapplication(21).Usingasophisticatedsetofsimulationmodelingtools,itwasshownthatundertheassumptionof100%penetrationrate,eco-speedharmonizationcouldresultinupto12%energysavings,butwithan8%reductioninmobility(i.e.,longertraveltimes).However,whentunedsothatmobilitywasunaffected,thentheenvironmentalbenefitswerearound5%.Ontheotherhand,

10

eco-cooperativeadaptivecruisecontrolwasshowntoprovideupwardsof30%energysavingsforagenericfreewaysegment.Whenappliedtoaregularfreewaywithon-andoff-ramps,thesavingswerearound15%.

RecentEnvironmental-ITSResearchProgramsintheEuropeanUnionIn2011,theEuropeanUnion(EU)setupWorkingGroupforCleanandEfficientMobility(WG4CEM)aspartoftheiMobilityForumwiththeaimtoidentifymostpromisingITSsolutionsforcleanandefficientmobility.Oneofthegroup’stasksistoprovideaprioritizedlistofrecommendedITSenvironmentalprojectsandaroadmapillustratingthepathwaysofresearch.ThisEuropeanworkinggroupconsistsofmembersfromroadauthorities/roadoperators,roadusersandautomotiveandinformationandcommunicationstechnology(ICT)industrystakeholdersinterestedincleanandefficientmobility.Connectedvehiclesandinfrastructurewereasubsetoftheproposedsolutions.Theresultsofthiseffortcanbefoundin(22).Inthissection,onlysomeofthemajorITSprojectsaimedatreducingGHGemissions,andinparticularthoseinvolvingconnectedvehicles,arehighlighted.Manyoftheseprojectswerefundedbyvarioussources,includingtheEuropeanCommission(EC),theEuropeanCommissionDirectorateGeneralforCommunicationsNetworks,Content&Technology(DG-CONNECT),theEuropeanUnion’sSeventhFrameworkProgramforResearch(FP7),andtheEUCompetitivenessandInnovationFrameworkProgramanditsPolicySupportProgram(CIP-PSP).TheseprogramsarecategorizedintothethreemajorITSareas.

VehicleSystemsTheEUcarriedoutamajorprograminconnectedvehiclescalled“eCoMove”whichwasfocusedon“cooperativemobilitysystemsandservicesforenergyefficiency.”ThisprogramexaminedthelatestV2I/I2VandV2Vcommunicationtechnologies,andcreatedanintegratedsolutioncomprisingeco-drivingsupportandeco-trafficmanagementtotacklethemainsourcesofenergywastebypassengerandcommercialvehicles.TheeCoMoveprojecttargetedthreemaincausesofavoidableroadtransportenergyuseinordertominimizefuelwaste:1)inefficientroutechoice;2)inefficientdrivingperformance;and3)inefficienttrafficmanagementandcontrol.Overall,theeCoMoveprojectshowedfuelsavingsofaround10%to20%foreco-drivingandapproximately10%savingsfortrafficsignaloperations(23).AnotherimportantprojectwastheECOSTANDproject,ajointEU-Japan–U.S.taskforcetodevelopastandardmethodologyfordeterminingtheimpactsofITSonenergyefficiencyandcarbondioxide(CO2)emissions.TheoverallgoalwastoprovidesupportforanagreementbetweenthethreeregionsonaframeworkforacommonassessmentmethodologyforquantifyingtheimpactsofITSonenergyefficiencyandCO2emissions(24).Currently,Compass4Disanongoingmulti-cityprojectinEuropethatisfocusedondeployingadvancedvehiclecooperativesystemstoimproveroadsafetyandenergyefficiencyandtoreducecongestion.Thisthree-yearEUco-fundedproject(startedinJanuary2013)isdeploying

11

threeservicesinsevencities(Bordeaux,Copenhagen,Helmond,Newcastle,Thessaloniki,VeronaandVigo),inordertoprovetheconcretebenefitsofcooperativesystemsforcitizens,cityadministrationsandcompanies.Compass4Dispilotingthreemainservices:aredlightviolationwarning,aroadhazardwarning,andenergy-efficientintersections.Theseservicesareinplaceforoneyearon334vehicles,includingbuses,taxis,emergencyvehicles,andprivatecars,reachingmorethan550users(25).Resultsonenvironmentalimpactsarepending.

TrafficManagementSystemsTheCooperativeSystemsforSustainableMobilityandEnergyEfficiencyorCOSMOprojectadoptedasystem-wideapproachtotheassessmentofenergyefficiency,measuringtheeffectofarangeofinnovativetrafficmanagementsystemsnotonlyonfuelconsumptionandemissionsofvehicles,butalsoontheenergyusedtooperateroadsideequipment.Theaimwastoprovideapracticaldemonstrationoftheeffectivenessofthesystemsandtoassesstheirimpactunderrealisticconditions.Theprincipalresultwasasetofvalidatedspecificationscoveringtheiroperational,technical,businessandorganizationalcharacteristics.TheCOSMOtestsiteswereinSalerno,ViennaandGothenburgandranfrom2010to2013(26).Ingeneral,CO2emissionreductionswereshownontheorderof5%to15%.TheCooperativeNetworkedConceptforEmissionResponsiveTrafficOperationsorConCERTOprojectwascarriedoutfrom2010through2013andusedhighlysophisticatedenvironmentaltoolstodevelopnext-generationtechnologiestoreducemotorvehicleemissionsbasedonreal-timeemissionmeasurements(27).TheCARBOTRAFprojectiscurrentlyunderwayandisfocusingondeveloping“ADecisionSupportSystemforReducingCO2andBlackCarbonEmissionsbyAdaptiveTrafficManagement”.TheoverallgoalistodeveloptoolsforadaptivelyinfluencingtrafficinrealtimetoreduceCO2andblackcarbonemissionscausedbyroadtransportinurbanandinter-urbanareas(28).

TravelInformationSystemsIn2012,theAssessmentMethodologiesforITSinMultimodalTransportfromUserBehaviortoCO2Reduction(AMITRAN)programbeganandranuntil2014.ThisprogramdevelopedaframeworkfortheevaluationoftheeffectsofITSmeasuresintrafficandtransportonenergyefficiencyandCO2emissions(29).TheEcoGemorCooperativeAdvancedDriverAssistanceSystemforGreenCarsprojectwascarriedoutfrom2010to2013andaimedtoprovideefficientconnectedvehiclesolutionstosupportelectricvehicles(EVs).ThegoalwastodesignanddevelopanEV-oriented,highlyinnovativeAdvancedDriverAssistanceSystem(ADAS)equippedwithsuitablemonitoring,learning,reasoningandmanagementcapabilities,thatwouldhelpincreasetheEV’sautonomyandenergyefficiency(30).

12

ResearchNeedsEnvironmental-ITSprogramshaveonlyemergedrecently.ResearchprogramsintheUnitedStates,theEuropeanUnion,andotherregionshavemadesignificantprogressindevelopingandtestingthesesystems.However,therearestillmanyresearchgapsthatneedtobeaddressed,someexamplesofwhicharediscussedbelow.

Environment-Mobility-SafetyNexusOvertheyears,wehaveseensomeITSprogramsfocusingonsafetyandmobilityalsohavingsignificantenvironmentalco-benefits.Thesebenefitsrangewidelyduetoanumberofvariablessuchastypeofapplication,technologyused,andpre-existingconditionbeforedeployment.Recently,anumberofITSprogramshaveemergedthatarespecificallydesignedtominimizetheenvironmentalimpactsoftransportation,someofwhicharebrieflydescribedearlierinthiswhitepaper.Themobilityandsafetyimpacts,bothattheindividualvehiclelevelandatthetrafficnetworklevel,oftheseenvironmental-ITSprogramsarenotwellunderstood.Whiletherehasbeensomeresearchonthistopic(e.g.,(31)),moreisneededtoimprovetheunderstandingoftheconnectionbetweenenvironment,mobility,andsafetyperformanceofanyITSprograms.

InducedTravelDemandOneconcernthathasemergedwithanytypeofITSimplementationisthepotentialforinducedtraveldemand.JustasithasbeenshownthatincreasedroadwaycapacitytypicallyleadstoincreasedVMT(e.g.,see(32)),somehypothesizethatifoverallmobilityimprovesduetoITS,thenpotentiallyVMTwillincrease.Todate,nodefinitivestudieshaveshownthiseffect.However,currentresearchisexamininghowautomatedvehiclesmayaffecttraveldemand(seee.g.,(33)).Preliminaryresultsshowthatwithamodestintroductionofautomatedvehicles,5%increaseinVMTmayoccur.Nevertheless,thegeneraleffectsofITSontraveldemandneedstobestudiedingreaterdetail.

ConclusionsInthiswhitepaper,state-of-the-practiceITSprogramsthatareenvironmentallybeneficialarehighlighted,spanningthethreemainareasofITS,includingVehicleSystems,TrafficManagementSystems,andTravelerInformationSystems.Forthelastseveraldecades,manyoftheseITSprogramshavebeentargetedatimprovingsafetyandreducingcongestion,withthesecondarygoalsofreducingfuelconsumptionandloweringcriteriapollutantandGHGemissions.ItisclearthatspecificenvironmentalbenefitscanbemaximizedwhenthesedifferentITSapplicationsare“tuned”sothatemissionsandfuelconsumptionarereduced.Furthermore,itisimportanttopointoutthatthereisnotasingleITStechnologysolutionthathasdemonstratedasignificantreductioninGHGemissions.Eachoftheenvironmental-ITSapplicationsdescribedinthiswhitepapertypicallycanreduceGHGemissionsintherangeof

13

5%to15%.However,mostoftheseapplicationsareadditive,thereforegreaterbenefitsmaybeachievedwhenacombinationofenvironmentallyfriendlyITSprogramsareputintoplace.Also,themobilityandsafetyimpactsofenvironmental-ITSprogramsarenotcurrentlywellunderstood.ItisclearthatasmoreoftheseITSprogramsaredeployed,comprehensiveimpactassessmentsoftheirenvironmental,mobility,andsafetyperformanceareneeded.EvenwiththeseITSoperationalimprovementsthatresultinreducedemissions,wemustalsobeconcernedaboutanypotentialinduceddemandeffects.Again,thispotentialneedstobemodeledandmeasuredasnewITSapplicationsaredeployed.Tocounteracttheseeffects,theITSprogramsmayhavetobecoupledwithsomespecifictraveldemandmanagementmeasures,suchaspricing.

14

References

1. U.S.EnvironmentalProtectionAgency,U.S.GreenhouseGasInventoryReport:1990-2013,seehttp://www.epa.gov/climatechange/ghgemissions/usinventoryreport.html,2015.

2. U.S.DepartmentofTransportation,IntelligentTransportationSystemsJointProgram

Office,NationalITSArchitecture,seehttp://www.iteris.com/itsarch/,accessedMay2015.

3. M.Barth,K.Boriboonsomsin,“Real-WorldCarbonDioxideImpactsofTrafficCongestion”,TransportationResearchRecord:JournaloftheTransportationResearchBoard,V.2058,pp.163-171.

4. M.BarthandK.Boriboonsomsin,''EnergyandEmissionsImpactsofaFreeway-BasedDynamicEco-DrivingSystem,''August,TransportationResearchPartD:Environment,Vol.14,ElsevierPress,pp.400-410,2009.

5. U.S.DepartmentofTransportation,FederalHighwayAdministrationExploratoryAdvancedResearchProgram,seehttp://www.fhwa.dot.gov/advancedresearch,2015.

6. V.Milanes,S.E.Shladover,J.Spring,C.Nowakowski,H.Kawazoe,M.Nakamura,“CooperativeAdaptiveCruiseControlinRealTrafficSituations”,IEEETransactionsonIntelligentTransportationSystems,Vol.15,No.1,pp.296-305.

7. P.Hao,G.Wu,K.Boriboonsomsin,M.Barth,“DevelopingaFrameworkofEco-ApproachandDepartureApplicationforActuatedSignalControl”,IEEEIntelligentVehiclesSymposium,Seoul,Korea,June28–July1,2015.

8. U.S.DepartmentofTransportation,UniversityTransportationCentersProgram,seehttp://www.rita.dot.gov/utc/home,2015.

9. NationalCenterforSustainableTransportation,seehttp://ncst.ucdavis.edu/,2015.

10. Mid-AtlanticTransportationSustainabilityCenter,seehttp://www.matsutc.org/,2015.

11. D.Kari,G.Wu,andM.Barth,“Eco-FriendlyFreightSignalPriorityUsingConnectedVehicleTechnology:AMulti-AgentSystemsApproach”,Proceedingsofthe2014IEEESymposiumonIntelligentVehicles,Dearborn,Michigan,June,2014.

12. K.Ahn,H.Rakha,“EcolaneApplications”,TransportationResearchRecord:JournaloftheTransportationResearchBoard,V.2427,No.1,pp.41-53.

15

13. U.S.DepartmentofTransportation,ApplicationsfortheEnvironment:Real-TimeInformationSynthesis(AERIS)ResearchProgram,seehttp://www.its.dot.gov/aeris/,2015.

14. VirginiaTechTransportationInstitute,seehttp://www.its.dot.gov/aeris/pdf/EcoDriving.pdf,2011.

15. CalmarTelematics,seehttp://ntl.bts.gov/lib/46000/46100/46187/FINAL_PKG_FHWA-JPO-12-051.pdf,2012.

16. UniversityofCalifornia,Riverside,seehttp://ntl.bts.gov/lib/45000/45600/45636/FINAL_PKG_FHWA-JPO-12-042_V3.pdf,2011.

17. UniversityofBuffalo,seehttp://www.civil.buffalo.edu/research/research-areas/area:transportation-systems-engineering/section:projects/project:an-evaluation-of-likely-environmental-benefits-of-lowest-fuel-consumption-route-guidance-in-the-buffalo-niagara-metropolitan-area/,2014.

18. M.Barth,S.Mandava,K.Boriboonsomsin,H.Xia,“DynamicECO-drivingforArterialCorridors”,IEEEForumonIntegratedandSustainableTransportationSystem(FISTS),June,pp.182-188.

19. H.Xia,K.Boriboonsomsin,M.Barth,“DynamicEco-DrivingforSignalizedArterialCorridorsandItsIndirectNetwork-WideEnergy/EmissionsBenefits”,JournalofIntelligentTransportationSystem:Technology,Planning,andOperations,Vol17,Issue1.

20. U.S.DepartmentofTransportation,AERIS-ApplicationsfortheEnvironment:Real-TimeInformationSynthesis:Eco-SignalOperationsModelingReport,publicationnumberFHWA-JPO-14-185,seehttp://ntl.bts.gov/lib/54000/54900/54930/Eco-Signal_Operations_Modeling_Report_-_Final_508_-_012615.pdf,2014.

21. U.S.DepartmentofTransportation,AERIS-ApplicationsfortheEnvironment:Real-TimeInformationSynthesis:Eco-LanesOperationalScenarioModelingReport,publicationnumberFHWA-JPO-14-186,seehttp://ntl.bts.gov/lib/54000/54900/54929/Eco-Lanes_Modeling_Report_-_Final_508_-_012615.pdf,2014.

22. EUWorkingGroupforCleanandEfficientMobility,seehttp://www.imobilitysupport.eu/library/imobility-forum/working-groups/active/ict-for-clean-and-efficient-mobility/reports-4/2332-wg4cem-final-report-131308.

23. Cooperativemobilitysystemsandservicesforenergyefficiency,seehttp://www.ecomove-project.eu/,2015.

16

24. ECOSTAND:JointEU-Japan-UStaskforceonthedevelopmentofastandardmethodologyfordeterminingtheimpactsofITSonenergyefficiencyandCO2emissions,seehttp://www.ecostand-project.eu/,2015.

25. EUCompass4Dresearchproject,seehttp://www.compass4d.eu/,2015.

26. Co-operativeSystemsforSustainableMobilityandEnergyEfficiency,seehttp://www.cosmo-project.eu/,2015.

27. Co-operativeNetworkedConceptforEmissionResponsiveTrafficOperations,seehttp://www.traffictechnologytoday.com/news.php?NewsID=27116,2014.

28. ADecisionSupportSystemforReducingCO2andBlackCarbonEmissionsbyAdaptiveTrafficManagement,seehttp://carbotraf.eu/,2014.

29. AssessmentMethodologiesforICTinmultimodaltransportfromUserBehaviourtoCO2reduction,seehttp://www.amitran.eu/,2015.

30. CooperativeAdvancedDriverAssistanceSystemforGreenCars,seehttp://www.transport-research.info/web/projects/project_details.cfm?id=44395,2015.

31. Boriboonsomsin,K.,Dean,J.,andBarth,M.(2014).“Examinationofattributesandvalueofecologicallyfriendlyroutechoices.”TransportationResearchRecord,2427,13-25.

32. NolandR.Relationshipsbetweenhighwaycapacityandinducedvehicletravel.TranspResAPolicyPract.2001;34:47–72.

33. MichaelGucwa,“MobilityandEnergyImpactsofAutomatedCars”,ProceedingsoftheAutomatedVehiclesSymposium,SanFrancisco,July2014.