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In recent years, shared mobility services have had a growing presence in cities all over the world. Developing methodologies to measure and evaluate the impacts of shared mobility has therefore become of critical importance for city authorities. This paper conducts a thorough review of the different types of methods that can be used for this evaluation and suggests a classification of them. The pros and cons of each method are also discussed. The added value of the paper is twofold; first, we provide a systematic recording of the state of the art and the state of the practice regarding the evaluation of the impacts of shared mobility, from the perspective of city authorities, reflecting on their role, needs, and expectations. Second, by identifying the existing gaps in the literature, we highlight the specific needs for research and practice in this field that can help society figure out the role of urban shared mobility.
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Sustainability2020,12,10504;doi:10.3390/su122410504www.mdpi.com/journal/sustainability
Article
EvaluationMethodsfortheImpactsofShared
Mobility:ClassificationandCriticalReview
AnastasiaRoukouni*andGonçaloHomemdeAlmeidaCorreia
Transport&PlanningDepartment,FacultyofCivilEngineeringandGeosciences,
DelftUniversityofTechnology,Stevinweg1,2628CNDelft,TheNetherlands;g.correia@tudelft.nl
*Correspondence:a.roukouni@tudelft.nl;Tel.:+31613248875
Received:19November2020;Accepted:14December2020;Published:15December2020
Abstract:Inrecentyears,sharedmobilityserviceshavehadagrowingpresenceincitiesalloverthe
world.Developingmethodologiestomeasureandevaluatetheimpactsofsharedmobilityhas
thereforebecomeofcriticalimportanceforcityauthorities.Thispaperconductsathoroughreview
ofthedifferenttypesofmethodsthatcanbeusedforthisevaluationandsuggestsaclassificationof
them.Theprosandconsofeachmethodarealsodiscussed.Theaddedvalueofthepaperistwofold;
first,weprovideasystematicrecordingofthestateoftheartandthestateofthepracticeregarding
theevaluationoftheimpactsofsharedmobility,fromtheperspectiveofcityauthorities,reflecting
ontheirrole,needs,andexpectations.Second,byidentifyingtheexistinggapsintheliterature,we
highlightthespecificneedsforresearchandpracticeinthisfieldthatcanhelpsocietyfigureoutthe
roleofurbansharedmobility.
Keywords:sharedmobility;transportationimpacts;evaluationmethods;cities;cityauthorities
1.Introduction
Inacontinuouslyurbanizedworld,thecomplexityofurbandwellers’needsisalsogrowing.
Citiesallovertheworldarefacingdifferentchallengesandneedtodevelopnewsolutionstofulfil
theircitizens’changingneeds,whilestrivingtowardsthegoalsofthe2030AgendaforSustainable
Development,andespecially“SustainableDevelopmentGoal11:tomakecitiesandhuman
settlementsinclusive,safe,resilientandsustainable”[1].Ontopofthat,currently,accordingtothe
UnitedNations,“duetoCOVID19,anunprecedentedhealth,economic,andsocialcrisisis
threateninglivesandlivelihoods,makingtheachievementoftheGoalsevenmorechallenging”[2].
Withmorethan90%ofCOVID19caseslocatedinurbanareas,citieshavebeenurgentlyforcedto
comeupwithnovelapproachesinordertosurvivethetempest[2].
Overthepastyears,sharedmobilityserviceshavehadagrowingpresenceincitiesalloverthe
world;thisphenomenonisbeingfacilitatedbytheincreasingadoptionofinformationand
communicationstechnology(ICT),whichistranslatedintothewideuseofsmartphones,social
media,anddigitalplatforms[3].Intheaftermathofthepandemic,therefore,itismoreimportant
thaneverforcitiestobeabletounderstandandassesstheimpactsofsharedmobility,asthiswill
helpthemplacesharedmobilityinthebiggerpictureofmakingaplantowardsanefficient,
sustainable,resilient,andpeopleorientedurbantransportsystem.Inthiscontext,theresearch
presentedhereinaimsatprovidingacomprehensiveandstructuredcriticalreviewofthestateofthe
artandstateofthepracticeofevaluationmethodsthatcanbeusedbycitiestoassesstheimpactsof
sharedmobility.Wehavereviewedacademicliteratureaswellassocalledgreyliterature—reports,
whitepapers,newsarticles,blogs,andwebsites—duetothefactthatthereisnolargevolumeof
researchyetfocusingontheyoungestmembersofthesharedmobilityfamily,suchasdockless
systems,transportationnetworkcompanies(TNCs)andescooters.Theobjectiveofthispaperis
hencetoprovideavaliddescriptionofthekeydimensionsofheterogeneitywithinresearchand
Sustainability2020,12,105042of22
practiceonthetopicoftheevaluationoftheimpactsofsharedmobilityandtoprovidethebasisfor
thefuturedevelopmentandapplicationofmethodstosupportcitiesintheirdecisions.
Asplaceswherepeople,ideas,andresourcesaregathered,citiesareattheforefrontofthe
transitiontowardsasustainablefuture.Theyalsooftenactasincubatorsforinnovationandtheyare
increasinglyembracingnoveltechnologies[4,5].Acrucialcomponentforthesuccessofthistransition
iscertainlytheurbantransportsystem.Environmentalpollution,trafficcongestion,parking
difficulties,longcommutingtimes,andlossofpublicspaceareonlyafewoftheurbanmobility
relatedchallenges[6,7].Urbanmobilityhasbeenexperiencinganeraoftransitionaswell,moving
towardsapersonalized,intelligentfuturethatisexpectedtobringtogetherthreemainmobility
trends—sharedmobility,electricmobility,andautonomousmobility[8,9].
Thegrowthofsharedmobilityispartoftheoverallboomingtrendofthesocalledsharing
economy,whichhasbeenflourishingsignificantlyinagrowingnumberofcitiesduringthelast
decade,andhasgatheredalotofattentionfromacademicsindifferentfields(e.g.,see[10–13]),
practitioners,aswellasthemedia.AccordingtotheFinancialTimes,weareenteringanerainwhich
consumerswillvalueaccessoverownershipandexperiencesoverassets[14].Theconceptofshared
mobilityreferstoprovidingaccesstoadestination,insteadofowningthevehiclethattakesyouto
thatdestination[15].
Itcantakeseveraldifferentforms,varyingfromsharingthetimeavailableforusingavehicleto
sharingaridewithothercommutersinthesamevehicle.Fromcarsharingandbikesharing,services
thatdatebackseveralyearsago,tothedisruptiveintroductioninthe2010softransportationnetwork
companies(TNCs)andmostrecentlytotheemergenceofsharedmicromobility,reflectedintheinflux
ofescootersinnumerouscitiesaroundtheglobe,sharedmobilitypresentsaplethoraofoptionsfor
peopletotravelinurbanareas.Severalstudiesexistthatfocusontheimpactsofsharedmobility,
examiningthemunderthelensofallthreepillarsofsustainabledevelopment—environment,
economy,andsociety.Developingmetrics,models,andmethodologiestomeasureandevaluatethis
widerangeofimpactsisofmajorimportanceforcitiesbecauseitisessentialtounderstandthemto
beabletoguidepublicpolicydevelopment[16,17].
Cityauthoritieshavethusimportantdecisionstomake.Theyhavetodecidewhetherthe
introductionofasharedmobilityservicewillbebeneficialfortheircityand,incasesinwhichsome
potentialdrawbacksareexpected(orestimated),theymustfindifthepositiveimpactsthatare
foreseenarestrongenoughtooutweighthenegativeones[18].Asthespectrumofavailableshared
mobilityoptionscontinuestogrow,boostedbytheprivatesector’sinnovations,thepublicsector
shouldrespondwithpoliciesandguidelinesthataimatthemaximizationofbenefitsthatthesenew
sharedservicescanbringtothecityandthecitizens[19].
In2020,afterasharpdecreaseinridershipthathasbeenreportedbymostsharedmobility
serviceprovidersduringtheinitialperiodoflocallockdownsandsocialdistancingmeasures
implementedduetoCOVID19,sharedmodesarenowbeingconsideredbymanycitiesasastrong
allyinsupportingurbanmobilityinthepostpandemicerathatliesahead.Moreandmorecities
worldwidearetryingtogiveadditionalspacetoactivemodesoftransport,inanattempttorelieve
pressureandavoidcrowdedsituationsinpublictransit,encouragingthiswayforpeopletowalkand
cyclemorewhilebeingabletomaintainaphysicaldistancefromoneanother.
Theremainderofthepaperisstructuredasfollows.Initially,anoverviewoftheexistingshared
mobilitymodesandservicesispresented,togetherwithsomeinsightsregardingtheirevolutionand
growthtrends.Theimpactsofsharedmobilityarethenintroducedandcategorizedintodifferent
groups.Thenextsectiondiscussestheroleofcityauthoritiesandthekeychallengestheyfacewhen
consideringtheintroductionofanewsharedmode/serviceintheirterritory.Thisisfollowedbya
presentationofthestateoftheartandthestateofthepracticeinmethodsthatarefoundinthe
literaturefortheevaluationoftheimpactsofsharedmobility,withacriticalview,discussingthe
strongpointsbutalsothedrawbacksand/ortheissueswhichrequirefurtherresearch.Thepaper
endswithgeneralconclusionsandperspectivesforfuturework.
Sustainability2020,12,105043of22
2.SharedMobility:Modes/ServicesandEvolution
Thereisalargevarietyofmodesandservicesfallingintothewidecategoryofsharedmobility.
Figure1presentsthesevenmaincategoriesofsharedmobilityaccordingtotheliterature—car
sharing,bikesharing,ridesharing,ondemandrideservices,(shared)micromobility,alternative
transitservices,andcouriernetworkservices.
Figure1.Sharedmobilitymodesandservices(Basedon:[15,19]).P2P:peertopeer.
2.1.CarSharing
Carsharingprogramshavealonghistory,especiallyinEurope,wheretheyfirstappeared
aroundthe1950sinSwitzerland,withtheUnitedStates(U.S.)andAsiafollowingafewdecadeslater.
Nowadays,carsharingserviceshaveapproximately32millionusersandcanbefoundinalmost50
countriesaroundtheglobe(2018data)[20].Asharpincreasingtrendwasnoticedafter2012,
especiallyinAsianmarkets[20].Variouscarsharingmodelsexist,havingstartedfromthestation
basedroundtripmodelandhavingevolvedintomanyalternativeschemes—oneway,freefloating,
andpersonalvehiclesharing(whichcanbefurtherdividedintopeertopeer(P2P),hybridP2P—
traditionalmodel,P2Pmarketplace,andfractionalownership)[19].
2.2.BikeSharing
BikesharingsystemsbeganinAmsterdam,theNetherlands,in1965,withaprogramknownas
“whitebikes”.Severalbicycles,paintedwhite,wereofferedtothepublictouseforfreebutthe
programstoppedshortlyafterwards,duetoproblemsrelatedtotheftandvandalism[21,22].From
theeraofthesocalled“firstgeneration”ofbikesharinguntilnow,ahugeevolutionhastakenplace
inthefield,reachingthepresent“fourthgeneration”ofbikesharing—highlyflexibledockless
systems,operatedusingICT,globalpositioningsystem(GPS)devices,andsmartphones,whichhave
revolutionizedbikesharingmarketsinrecentyears[21,22].Asof2018,morethan1600publicbike
sharingsystemsexistedallovertheworld,fromonly17in2005,withover18millionbicycles[19].In
additiontothedistinctionbetweendockedanddockless(freefloating),bikesharingsystemscanalso
beofferedonaclosedcampus(e.g.,see[23]),aspersonalvehiclesharingsystems(P2P/marketplace),
orasbikeleasesystems(e.g.,seetheDutchSwapfietssystem,[22]).
2.3.Ridesharing
Ridesharingenablespeoplewhoareheadingtothesamedestinationortodestinationslocated
closetooneanother,andwhosestartingpointsarealsoadjacent,tosharetheridethere[19].Although
onceagainnotamoderninvention,ithasmetwithgrowingpopularityduringthelastdecade,dueto
Shared
Mobility
Car sharing
Station-based Free-floating
(dockless)
Personal
Vehicle
Sharing (PVS)
Round-trip
One-way
P2P Car sharing
Hybrid P2P – Trad itional
Car sharing model
P2P Marketplace
Fractio nal Ownershi p
Bike sharin g
Station-based
Round-trip
One-way
Free-floating
(dockless)
Closed
Campus
Personal
Vehicle Shari ng
(PVS)
P2P Bike sharing
P2P Marketplace
Ridesharing
Carpooling
Vanpooling
On-dem and
ride services
Ridesourcing/
TNCs Ridesplitting E-hail
(Shared)
Micromobility
E-scooters E-bikes (E)-mopeds
Alternative
Transit
Services
Shuttles
Microtransit
Courier Network
Services (CNS)
P2P Delivery
Services
Paired on-demand
passenger ride and
courier services
Bike leasing
Sustainability2020,12,105044of22
theincreasinguseofonlineplatformsandaspartoftheoveralltrendofthesharingeconomy[24].In
theU.S.,carpoolingwasfirstintroducedasaregulationpolicytodecreasefuelconsumptionduring
WorldWarII.Itsusepeakedinthe1970s,withapproximately20%ofallcommutetripsbeing
performedbycarpool.Nowadays,carpoolingisaverypopularmodeoftransportforworkcommuters
intheU.S.,comingsecondonlytosingleoccupancyvehicles[25].Vanpoolinguseslargervehicles,
typicallyforupto15people,andtheuserscansharethetripcostsandsometimesalsothedrivingtime
[15].
2.4.OnDemandRideServices
Ondemandrideservicesusedigitalplatformsandapplicationstoconnectdriverswith
passengers.Thiscategorycanbefurtherdividedintoridesourcing,orasitismostoftencalled,
transportationnetworkcompanies(TNCs),ridesplitting,andehailservices.Thedifferencewith
ridesharing(describedabove)isthatinthecaseofridesourcing,driversdonotjusthappentogothe
samedestinationasthepassengersanddecidetocombinetheride.Rather,theyheadtowhichever
locationsthepassengersdemand,asiftheyweretaxidrivers.Ridesourcinghasdisplayedafastand
massivegrowthduringthelastdecadeandthushasprovidedtriggersforintensedebatesoverits
impactsonfutureurbandevelopment[19,26,27]).Theehailserviceswereintroducedbytaxi
operatorsasaresponsetoTNCs.Withehail,apassengercancallataxithroughanapplicationvery
similartotheridesourcingones.Nevertheless,thepriceinthiscaseisfixedanddependsonthelocal
taxicharges;itisnotdemanddriven,asinthecaseofTNCs[19].Ridesplittingcanbeconsidereda
combinationofridesourcingandcarpooling;itworkswithdifferentpassengerswhoseoriginand
destinationhappentobesimilarlocations,andthereforetheydecidetosharearidesourcingrideto
saveonthefee.Usuallythepassengersinthiscasehavetowalktoapickuppointsomemetersaway,
wheretheymeetthedriverandtheirfellowtravelers[27].
2.5.Micromobility
Micromobilityisatermthathasbeenincreasinglyusedsince2017,whenthefirstsharede
scootersappearedincities(inthispaperthetermescootersreferstostandingescooters,whereas
otherescootersarereferredtoasemopeds).Micromobilityservicesareadvocatedmostlybythe
youngergenerations,whousedifferentoptionsinthewaytheytravel,comparedtotheirantecedents
[28],andwhoarenaturallymorephysicallyskilledintheuseofthesevehicles.Despiteitsexplosive
popularityincitiesallovertheworld,thereisnotyetaclearconsensusamongresearchersonwhat
exactlycomprisesmicromobility.Accordingtosomedefinitions,“sharedmicromobilityistheshared
useofabicycle,scooter,orotherlowspeedmodes”(see[29]).Otherresearchersconsiderthatone
shouldnotincludebikesharinginthecategoryofmicromobility,asithasamuchlongerhistoryin
citiesallovertheworld,thereforeitshouldformaseparatecategoryofitsown.Thisistheapproach
wefollowinthisarticle,adoptingthefollowingdefinition—“Microvehiclereferstotheclassoftiny
vehiclessuchasebikesandescooters,excludingsolelyhumanpoweredvehicleslikepedalonly
bikes.Micromobilityreferstothetravelmodecategorythatusesmicrovehicles”[30].
In2018,45milliontripsweremadeusingsharedescootersandebikesintheU.S.,surpassing
bikesharingtrips(36.5million)forthefirsttime[31],whereasinEuropethenumberofcurrente
scooterusershasreached20million[28].FromMarch2020,micromobilityservicesworldwidehave
experiencedaconsiderabledropinridership,inlinewiththegeneraldeclineindemandthatthe
measurestakenbygovernmentstofighttheCOVID19pandemichadinitiallybroughttoallmodes
ofsharedmobility.Nevertheless,theyareexpectedtohaveakeyrole,togetherwithbikesharing,in
thepostpandemicmobilityera,asmoreandmorecitiesintroducenewbikecorridors,aswellas
discussingstrategiesandlegislationtosupportactivetransportandrelievepressurefrompublic
transitnetworks.
Sustainability2020,12,105045of22
2.6.AlternativeTransitServices
Alternativetransitservicescaneitherrefertomicrotransitorshuttleservices,whichoperate
simultaneouslyandoftencomplementarytopublictransportoptions,buttheycanhavesome
flexibilityintermsofitinerary(timeand/orroute).Theycanoperateonademandresponsivebasis
and/oronmorefixedrouteconnections[19].Alternativetransitservicescanalsoincludeinformal
sharedparatransitservicesthataremetinthedevelopingworldsuchasamaphelainSouthAfrica
[32],danfosinNigeria[33],trotrosinGhana[34],winsinThailand[35]orthepostSovietminibuses,
knownasmarshrutkas,inGeorgia[36].
2.7.CourierNetworkServices
Asharedservicethathasseensignificantgrowthrecentlyiscouriernetworkservices(CNS).
CNSoperateonthesamebasisasTNCs,usingadigitalplatformthatconnectssupplyanddemand.
Inthiscase,insteadofpassengers,driverscanconnecttoconsignersandagreetodeliveroneormore
packagestotheconsignees.Thecourierscanusetheirpersonalvehicles(cars/motorcycles)orbicycles
toperformthetransfer,andsometimesCNSandTNCservicescancoexistinthesameride.Aswe
haveseenwithcarsharingandbikesharing,P2Pserviceshavestartedtoevolveinthiscategoryas
well[19].Thepresentpaperfocusesonpassengertransport;therefore,wearenotgoingtoelaborate
furtherontheroleandimpactsofCNS,remainingawarethatanintriguingdimensionfor
forthcomingresearchwouldbetoexpandthepresentresearchstreamtosharedfreightandlogistics.
3.CategorizingtheImpactsofSharedMobility
Beforediscussingtheavailablemethodsandapproacheswithwhichtheimpactsofshared
mobilitycanbeevaluated,itisimportanttohaveacomprehensiveunderstandingofwhattheterm
“impacts”entailsinanurbancontext,asitcanrefertonumerousdifferentthings.
Anumberofstudieshavedealtwiththewaysbywhichsharedmobilitycanaffectacity,and
thevolumeofliteratureisbeingcontinuouslyenrichedwiththelaunchofnewsharedmodeslike
sharedebikesandescooters.Theimpactsofthemorerecentoneshavebeeninvestigated,as
expected,toamorelimiteddegreesofar,incomparisonwithmoreestablishedsharedmodesthat
havebeenoperatingfordecadesalready,suchascarsharing,ridesharing,andtraditionaldocked
bikesharing.Evenregardingthesamemodes/services,therearedifferencesinthenumberofexisting
studies,dependingonthetypeofbusinessmodel.Forinstance,stationbasedroundtripcarsharing
hasbeenstudiedforalongertimethanfreefloatingcarsharing,whichisamorerecentvariation.
Thesameholdsforstationbasedandfreefloatingbikesharing,respectively.Theboostedpopularity
ofondemandrideserviceshasledtoseveralresearchersstartlookingattheirimpactondifferent
aspectsoftheurbanrealm.
Itshouldbekeptinmindthatalthoughthereismuchevidenceintheliteraturethatshared
mobilityhasthestrongpotentialtobringnumerousbenefitsandpositiveeffectstocities,itisalso
clearfromtheresearchperformedsofarthatsharedmobilityisnotandshouldnotbetreatedasa
panaceaorsomekindofsilverbullettoalltheurbanchallengesdiscussedinSection1ofthispaper.
Somestudieshavefoundthattheintroductionofasharedmobilitymode/servicehasresultedinfact
insomeundesirableconsequences,suchasadditionalvehiclekilometerstraveledandtrafficjams,
leadingtoariseinemissions,incitieswhereTNCsbegantheiroperations(e.g.,see[37–39]).In
addition,therehavebeencaseswheretheintroductionofanewsharedmobilitysystemhasbeen
provenunsuccessfulinanareaanditceasedoperationshortlyafteritsimplementation(e.g.,see[40]).
Therefore,potentialreboundeffectsshouldnotbeoverlooked.
Asthefocusofthispaperisnottoprovideadetailedreviewoftheliteratureregardingthe
impactsthemselves,butrathertoprovidethoroughinsightsonthewaysbywhichtheseimpactscan
beevaluated,inthefollowingparagraphswearegoingtosummarizethekeyareasofimpactby
placingtheminwhatweconsidertobethesixmaincategories,namely,environment,travel
behavior,builtenvironment,society,trafficconditions,andeconomy.Fromthesebroadcategories,
thehighestnumberofstudiesandreportsbelongstothecategoriesofenvironmentandtravel
Sustainability2020,12,105046of22
behavior.Themaincategoriesofimpactsandthekeyareasthatbelongtoeachofthemareillustrated
inFigure2.
Figure2.Maincategoriesandkeyareasofimpactsofsharedmobility.VKT/VMT:vehiclekilometers
traveled/vehiclemilestraveled.
3.1.ImpactontheEnvironment
Theimpactofsharedmobilityontheenvironmentisundoubtedlycrucial,asminimizingthe
environmentalimpactoftransportationingeneralhasacentralroleinensuringasustainablefuture
forcities.Investigatingthiscanbeviewedaspartoftheoverallresearchstreamthatcallsforthe
decarbonizationofcitiesandsearchesfornewwaysofachievingthisgoal.Somestudieshavelooked
intotheimpactofsharedmobilityonCO2/greenhousegas(GHG)emissions[41–43],energy
consumption[44,45],airquality[46],andnoisepollution[47,48].Althoughthemajorityofstudies
examinetheimpactontheenvironmentofmainlycarsharing,bikesharing,ridesharing,andmore
recentlyridesourcingschemesoracombinationofthose,theenvironmentalimpactofnovelshared
mobilityservices,suchasescooters[49,50]andebikes[51],hasonlyrecentlystartedtobeaddressed.
3.2.ImpactonTravelBehaviorandtheBuiltEnvironment
Regardingtheimpactofsharedmobilityontravelbehavior,therearestudiesthatexaminehow
modechoiceisaffectedwhensharedmodesbecomeanavailableoptionandwhetheramodalshift
isobservedandtowardswhichmode(s)[22,52–54].Otherresearchhasinvestigatedtheroleofshared
mobilityinfirst‐ andlastmileconnectivitywiththeurbanpublictransportnetwork[55–58].The
impactonvehicleownership,whichcanbereflectedinthewillingnessofsharedmobilityusersto
skiporpostponeacarpurchaseortostopusing/sellacartheyalreadyownhasalsobeendocumented
byseveralresearchers,andsohastheimpactonthevehiclekilometerstraveled/vehiclemilestraveled
(VKT/VMT)[43,45,59–61].Otherresearchershavelookedintotheimpactsandpotentialsynergiesof
sharedmobilitywiththepromotionofactiveandmultimodaltransport[48,56,62–64].Asforthe
impactonthebuiltenvironment,threemainthemeshavebeenthetopicofresearchsofar—the
potentialimpactsonparkingsupply[65],landuse,andurbanaesthetics[66,67].
3.3.ImpactontheEconomy
Impacts of
Shared
Mobility
Environment
Travel behavior Built
environment
Society
Economy
Mode choice
Vehicle ownership
GHG Emissions
Air quality
Lifestyle
Environmental
awareness
VKT/VMT
Health
Traffic
conditions
Congestion
Car fleet size
Transportation
Equity
Number of
accidents
Parking supply
Energy
consumption
Individual and
household leve l
costs
Travel time
Employment
Multi-modality
Economic activity
near hubs
Active transport
Land use
Trip generation
First/last mile
connections
Urban
aesthe tics
Sustainability2020,12,105047of22
Theuseofsharedmobilitycanimpacttheeconomyinvariousways;itcanleadtocostsavings
onanindividualandhouseholdlevelbecausepassengerssharevehiclesandrides,anditcanalso
reducetheneedforvehicleownership,leadingtomoresavingsandthusallowingcitizenstohavea
largeramountofmoneyavailableforothergoodsandservices.Thisway,itcanalsohaveanimpact
ontheoveralleconomicactivityoftheareanearthesharedmobilityhubs.Furthermore,shared
mobility,andespeciallyTNCsandCNS,influencetheemploymentlevelsofanarea,withthe
recruitmentofdriversinanondemandbasis[44,66].
3.4.ImpactonTrafficConditionsandTransportationEquity
Theimpactofsharedmodesoftransportontrafficconditionscanbefurthersubdividedintothe
impactsoncongestion[42],tripgeneration[68],carfleetsize,traveltime[69],andtheimpacton
safety,whichisusuallyreflectedonthenumberofaccidents[48].Intermsofthesocietalimpactof
sharedmobility,animportantcomponentistheimpactontransportationequity[65].Somestudies
arealsostartingtolookattheeffectontransportationequityofthenewestmembersoftheshared
mobilityfamily—[26],docklessbikesharing[21]anddocklesssharedebikesandescooters[70].
Otherresearchershaveinvestigatedtheimpactthatsharedmobilitycanhaveonthehealthofcitizens
[44,70],ontheirlifestyle,aswellasonthecreationofenvironmentalawareness[71,72].
3.5.ImpactofShared(Autonomous)ElectricVehicles(S(A)EVs)
Asmentionedintheintroductionofthispaper,inadditiontosharedmobility,theothertwo
majortrendsthatareexpectedtohaveanincreasinglyessentialroleinurbanmobilityintheyearsto
come,especiallywhencombinedwithsharedmobility,areelectricandautonomousvehicles.There
isagrowingsegmentoftherecentliteraturethatfocusesontheimpactsofthisspecificcomponent
ofsharedmobility—sharedelectricvehicles(SEVs);sharedautonomousvehicles(SAVs);andthe
combinationofthetwo,sharedautonomouselectricvehicles(SAEVs).Thesevehiclescanbepartof
carsharing,ridesharing,ondemandrideservices,and/oralternativetransitservicefleets.
TherearestudiesthatinvestigatetheimpactsofSAVs,SEVs,and/orSAEVsonallthecategories
discussedonthissection:theenvironment[73–77],travelbehavior[76,78–80],thebuiltenvironment
[77,81],society[82,83],trafficconditions[84–87],andtheeconomy[88].Foracomprehensivereview
ofexistinguptodateworkregardingtheimpactsofsharedautonomousvehicleservices,see
Narayananetal.[89].
4.TheRoleofCityAuthorities
Cityauthorities’initiativescanhelpinenhancingsharedmobility’suseandacceptanceamong
citizens[90].Cityauthoritiescansupportsharedmobility,forinstancebyprovidingdesignatedon
streetparkingspotsforcarsharingvehiclesandbyestablishingagreementswithcarsharingservice
providersregardingpublicoffstreetparking.Moreover,whenofferingsupport,theauthorities
shouldalsomakedecisionsonadditionalissuessuchastheintegrationofsharedmobilitywiththe
existingurbantransportationsystem[91].
Researchonsharedmobilitycanassistlocalauthoritiesanddecisionmakersinobtainingamore
concreteideaoftheimpactsofsharedmodes,andintryingtoenhancethepositiveimpactsandlimit
thenegativeones.Differencesinservicemodels,localcircumstances,datacollection,anddata
analysismethodscanneverthelessleadtoinconsistencies,especiallywhenthedataavailabilityis
limited,andtheanalysisisperformedonanaggregatelevel[48].Therefore,accordingtoShaheen
andCohen[48],“itcanbechallengingtoprovideacomprehensiveandunbiasedpicture”.
BondorováandArcher[47]emphasizethatwhentheimpactassessmentsofsharedmobilityare
performedbysharedmobilityprovidersthemselvesorbycompaniesthathavebeenemployedby
themtodoso,theresultshavetobeinterpretedcarefullybecausetheyoftenlackindependenceand
theyalsomightnotprovidethoroughinformationabouttheirmethodologicalapproach.Someofthe
mostindependentandcomprehensiveevaluationsthathavetakenplacesofarhavecitiesintheU.S.
Sustainability2020,12,105048of22
astheirfocus,andthereforetheirfindingsarenotnecessarilyrepresentativeofthesituationin
Europeancities[47].
Oneoftheveryfewattemptssofar—tothebestofourknowledge—forthedevelopmentofa
tooltocontributetothebetterunderstandingofsharedmobilityservicesandtheirimpactandto
supportcityauthoritiesindefiningsuitablepoliciestomaximizethebenefitsinvolvedwas
undertakenbytheSharedUseMobilityCenterintheU.S.Thisorganizationhaspublishedthebeta
versionofanonlinetoolcalledtheSharedMobilityBenefitsCalculator.TheSharedMobilityBenefits
Calculatorwaslaunchedasatooltoestimatetheemissionsbenefitsfromdeployingvariousmodes
ofsharedmobilityanditsdevelopersclaimthatitcanbeusedtosetandmonitorgoalstowards
reducingcongestion,householdtransportationcosts,andcarbonemissionsfrompersonalvehicles.
ThetoolisbasedonlyonU.S.cities,anditincludescitieswithmorethan100,000residents[92].
Itappearsthatlocalauthoritiesinmanycitiesarenotwellpreparedtomanageandregulate
suchdisruptiveservices[93].Theextremelyfastadoptionratesofsharedescootersinurbancontexts
aroundtheworldhashighlightedthelackofregulatoryframeworksforemergingmobilitymodes.
Theresponseofcitiestothetrendofsharedmicromobilityvariesalot,fromcompleteprohibitionin
somecasestototalopennessinothers,withmanyinbetweensolutionsaswell[28].
Citiesallovertheworldarefacingdilemmasrelatedtohowbesttodealwithsharedmobility,
andhowitcanbepartoftheirstrategiesfortacklingthechanging,complexurbanchallengesrelated
tomobilityandlanduse.Thisiscurrentlymoreurgentthanever,forreasonsrelatedtothe
achievementoftheUNSustainableDevelopmentGoalsandtheaftermathoftheCOVID19
pandemic,asdiscussedinSection1.Thereisthusanundeniablyincreasedinterestinimplementing
sharedmodesincities,initiatedbynewcompaniesappearingonthemarkettooffersuchmobility
services,butoftenalsobythewishesofthetravelersthemselveswhoexperiencesimilarservices
elsewhere.Citieshavetomakesurethattheintroductionofnewsharedmodeswillindeedfitthe
needsofthecityandcitizens,andnottheotherwayaround.
Manycitiesarethusfacingchallengesinunderstandingwhethersharedmobilitywouldbeable
toeffectivelybringanysubstantialbenefittotheirterritories,andhowtheexistingurbantransport
systemwouldreactwhendemandforthenewmode(s)startstogrow.Thedifficultyinforecasting
andevaluatingtheimpactsofsharedmobilitycancreatestressforthedecisionmakersandcanlead
totheintroductionofblurredpoliciestoavoid“stayingbehind”.Therefore,thereisaclearneedto
providetherightmethodsandtoolstosupportthemintheirdecisions.
5.DiscussionoftheAvailableMethodsfortheEvaluationofSharedMobilitybyCity
Authorities
Ageneralobservationthatcanbederivedfromourliteraturereviewisthatthereisalarge,
heterogeneouspoolofdifferentapproachesthatresearchershaveusedtotrytoevaluatetheimpactsof
sharedmobility,butaconsiderablepercentageoftheexistingstudiesarecasespecificandexploratory,
andtheyshouldthereforebecarefullyinterpretedwhentryingtoscaleuportransfertheirresults.
Moreover,thescopeofthisworkistolookattheevaluationprocessfromacityperspective,inthe
directionofassistingthedecisionmakersinthechallengingprocessofdecidingonthemostsuitable
methodorcombinationofmethodstoapplytoassesstheimpactsofsharedmobility.
Inthatsense,wearenotinterestedinofferingaclassificationofallthevariationsofthemethods
thathaveeverbeenusedbyacademics,researchersandpractitionerstoevaluatesharedmobility’s
perksandpitfalls.Weclassifythemaincategoriesofoptionsthatcanbeusedtoevaluatetheimpact
ofsharedmobilityinaclearformatthatismeaningfulnotonlytoacademicsandresearchersbutalso
tocityauthoritiesanddecisionmakers—thepeoplewhooftenfacethedifficultdecisionsregarding
theimplementationofsharedmobilityprograms.
Wedividedtheevaluationmethodswhich,accordingtoourviews,arethemostrelevantonesthat
canbeofinteresttocitiesintoseveralmaincategories,andthenseparatedthesecategoriesintotwo
groups,basedonthetimeframeinwhichtheycanbeemployed—thosethatcanbeusedbeforethe
introductionofanewsharedmobilitymode/servicetoacity(exanteevaluation)andthosethatcanbe
usedafterthenewmode/servicehasbeenimplemented(expostevaluation).Thatbeingsaid,several
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citieschoosetorunpilots,whichentailshort,tryoutperiodsfortheimplementationofasharedmode,
towitnesswhetherthenewserviceprovidedwillhaveapositiveimpactonthecity,inarelativelymore
“safe”environment,withlowerrisksinvolvedduetothetemporarynatureofthepilot.
Figure3illustratesthemaincategoriesofevaluationmethods,classifiedbasedonthetimeframe
inwhichtheycanbeused,inlinewiththedistinctiondescribedabove.ItcanbenoticedinFigure3
thatsomeofthecategoriesappearinbothtimeframes,astheycanbeemployedeitherfortheexante
ortheexpostevaluationoftheimpactsofsharedmobility.Adiscussionofeachoneofthecategories
mentionedinthediagramfollowsbelow.
Figure3.Classificationofthemainmethodsavailablefortheevaluationoftheimpactsofshared
mobility.
5.1.ExAnteEvaluation
5.1.1.StatedPreference/StatedChoiceSurveys
Statedpreference(SP)orstatedchoice(SC)surveyshavebeenwidelyemployedfordecadesin
transportandotherfieldstoidentifybehavioralresponsestosituationsofchoicewhichhavenotyet
beenrevealedinthemarket[94].Theyhelptoidentifyindividualpreferenceswithoutrequiring
excessivecognitiveeffortbytherespondents.ThishasmadeSPsurveysoneofthemosteffectiveand
widespreadwaystostudybehavioraldecisions[95].SPsurveyscanbevaluableincollecting
informationaboutnewpolicies,forinstance,theintroductionofanewtransportmodeoraroad
pricingscheme[96].Thistypeofsurveyusuallyincludesquestionsrelatedtosociodemographic
characteristicsoftherespondents,followedbyquestionsaimingatselectinginformationaboutthe
travelpatternsandpossiblyfrequentlyrepeatedorigindestination(OD)pairs.Then,theyrequest
responsestoquestionscorrespondingtohypotheticalsituationswhichinvolveatransportoption,
notyetavailablewhenthesurveyisconducted,with“whatwouldyoudoif…?/whatwouldbeyour
choice?”typeofquestions.
Before the introduction (ex-ante)
Pilot
Implementation (ex-post)
Benchmarking
Stated preference/
Stated choice surveys
(shared mode specific)
Transport modeling
Analysis of da ta from mobilit y servic e
providers (standardized or/and not
standardized)
Revealed preference surveys
(shared mode specific)
How can cities evaluate the impacts of shared mobility?
Implementation of new
shared mobility
service(s)
Analysis of oth er data (e.g. number of accidents,
complaints, activity data, feedback from focus
groups/stakeholder and cit izen en gagement etc.)
Transport modeling/
Data analysis
Household Travel surveys/
Mobility surveys
Available methods
Household Travel surveys/
Mobility surveys
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AftertheinformationiscollecteduponcompletionoftheSPsurvey,somefirstconclusions
regardingtheexpectedattitudesoftheparticipantstowardsthenewtransportoptioninquestioncan
bedrawnbyperformingasimpledescriptivestatisticalanalysistocomeupwiththepercentagesof
peoplethatarelikelytoembrace/rejectthenewservice.Thedatagatheredcanthenbeusedby
researchersasaninputtodifferenttypesofmoresophisticatedmodelingtechniques—whichusually
belongtothefamilyofdiscretechoicemodeling—torevealmorecomplex,hiddeninteractionsamong
theexaminedvariables.ExamplesofsuchmodelsthathavealreadybeenusedtoanalyzeSPsurvey
datainthefieldofsharedmobilityaremixedlogitmodels[97],mixednestedlogitmodels[53],and
orderedprobitmodels[78,98].
SPsurveyscanbeusedtoexaminetheimpactthatsharedmodes/servicesareexpectedtohave
onthetravelbehaviorofcitizens.Morespecifically,thewillingnesstousesharedmodescanbe
estimated(e.g.,see[80])aswellasthemodalshiftpatternsbetweensharedmodesandprivatecars,
publictransport,and/orcycling(e.g.,see[97]).Inaddition,SPsurveydatacanbeusedtoexamine
whichcharacteristicsofasharedmodeareconsideredvaluableforpotentialusersandwould
thereforebevitalforitsadoption(suchasconvenientaccesstothesharedvehicles,parking
availability,etc.)(e.g.,see[53,97]).Theimpactoncarownership[98]andtheadoptionratesofshared
vehiclescanalsobeestimatedusingtheSPdataunderdifferentpricingscenarios[78].
OneoftheimportantstrengthsofSPsurveysisthefactthattheoptionsofmodesorservicesare
notlimitedtotheavailableonesatthetimethatthesurveyisconducted,butthedesignersofthe
surveyhavethefreedomtobecreativeandinvestigatemanydifferentpotentialscenariosifthey
wish.Becauseofthis,itispossibletogatheralargervolumeofinformation,comparedtosurveys
thatfocusonlyonexistingoptions[99](asinthecaseofrevealedpreferencesurveys[99],whichwe
describeinSection5.2.1).
However,asallsurveybasedstudiesexploringthesphereofhumanbehavior,theSPapproach
issubjecttocertainlimitations,mostlyconcerningselfreportedandselfselectionbias,whichshould
beconsideredwheninterpretingtheirresultstoavoidvalidityissues.Selfselectionbiascanoccurin
caseswhenmanyofthepeoplewhoagreetoparticipateinasurveyaboutaparticularmode,bike
sharingforinstance,couldbecyclistenthusiasts,whichcouldleadtoabiasedoutcomeinfavorof
bikesharing,whichmaynotnecessarilyreflecttheperceptionsofthemajorityofthecommunitythat
thesurveysampleissupposedtorepresent[70].Selfreportedbiascanarisebecausepeople
sometimesdonotprovidefullyaccurateinformationregardingtheirtravelbehavior;e.g.,intermsof
theextentorfrequencyoftravel,theexacttimesanddaysthatacommutetookplace,etc.[48].InSP
surveysthereisalsothepossibilityoftheexistenceofhypotheticalbias.Thisbiasreferstothe
tendencyofrespondentstoreportawillingnesstopaythatexceedswhattheyactuallypayusing
theirownmoneyinreallifeexperiments[100].Cautiousdesignandimplementationofthesurvey
contributestoreducingtheriskofoccurrenceofsomeoftheaforementionedbiases,butsomeothers
areintrinsicandthusmoredifficulttoeliminate[99].Forthesereasons,theuseofsuchaninstrument
hastobecarefullyconsidered,makingsurethatitispossibletocontrolforthesourcesoferrorand
preferablycombiningitwithrevealedpreference(RP)dataifavailable(seeSection5.2.1).
5.1.2.Benchmarking
ComparedtoSPsurveys,whichhavebeenaroundfordecadesalready,theconceptof
benchmarkingismorerecent.Camp[101]definedbenchmarkingas‘‘thesearchforindustrybest
practicesthatleadtosuperiorperformance”.Inthecontextofcityplanning,benchmarkingis“a
systematicandcontinuousmethodthatconsistsofidentifying,learningandimplementingthemost
effectivepracticesandcapacitiesfromothercitiesinorderforone’sowncitytoimproveitsactions”
[102,103].Focusingonurbantransport,benchmarkinghasproventobeabletoenhanceandimprove
performancethroughlearningfromothercitieswithsuperiorperformance[104].
Inthecontextofsharedmobility,benchmarkingstudiescanbeconductedtohelpavoid
duplicativeresearch,toreduceoverallcosts,aswellastoaccelerateimprovementstotheurban
transportationsystem.Theapproachusuallycomprisesthreesteps—aliteraturereview,interviews
andmeetingswithexpertsinselectedcities,andsynthesisoftheinformation.Typically,thecitiesare
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selectedbasedonfactorssuchasthesizeandscaleoftheirsharedmobilitysystemsandtheexistence
ofpoliciesrelevanttothecitythatisinterestedinimplementingthesharedmobilityprograms[105].
Benchmarkingappearstostillhaveroomtodeployitsfullpotentialinexploringtheprosand
consofsharedmobility,asnotmanyexamplesofapplicationsofcomprehensivebenchmarking
studiesfocusingonsharedmobilityhavebeenfoundintheliterature.Inpractice,acommon
phenomenoninEuropeancitiesthatareinvolvedindifferentEUfundedprojectsinthewiderarea
ofsustainablemobilityisthecreationofnetworkstoexchangeexperiencesandlessonslearnedand
trytoimprovetheirurbanmobilitysystemsbystudyingthesuccesses(andfailures)oftheir
counterparts.Thiscanbeseenasakindofbenchmarking,withoutnecessarilybeingclassified
officiallyassuch.
SomeexamplesoftheaforementionednetworksinEuropeincludethePOLISnetwork,the
CIVITASForumNetwork,andthenetworksoftheURBACTprogram.ThePOLISnetworkconnects
localandregionalauthoritiesacrossEurope,whichcanthenworktogethertopromotesustainable
mobilitythroughthedevelopmentofinnovativetechnologiesandpolicies[106].TheCIVITASForum
Network“isaplatformfortheexchangeofknowledge,ideasandbestpracticeamongEuropeancities
regardingsustainableurbantransportpolicies”[107].TheURBACTprogramisaEuropean
TerritorialCooperationprogramwiththeobjectiveof“enablingcitiestoworktogetheranddevelop
integratedsolutionstocommonurbanchallenges,bynetworking,learningfromoneanother’s
experiences,drawinglessonsandidentifyinggoodpracticestoimproveurbanpolicies.”Withinthe
URBACTtherearenetworksfocusingondifferenttypesofurbanchallenges,suchasurbanmobility
(thecurrentnetworksfocusingonurbanmobilityareRiConnect,Space4People,andThrivingStreets)
[108].
However,beforeapplyingbenchmarkingorbeingengagedinanykindofprocessthatinvolves
comparingtheperformanceoftheirurbanmobilitysystemwiththatofothers,citiesshouldalsobe
awareofsomelimitations,firstandforemosttheoneresultingfromthenatureofthemethoditself—
studyingtheimpactoftransportservicesondifferentgeographicalcontextscaninvolvecrucial
differencesinissues,rangingfromexistingregulations,legislation,andpoliciestosocio
demographicindicators,densityofneighborhoods,livingconditions,citizens’behavior,traditions,
andculture,tonamejustafew.
5.2.ExPostEvaluation
5.2.1.RevealedPreferenceSurveys
Revealedpreference(RP)surveysinvestigatechoicesthathavealreadybeenmadeby
individualspriortothetimethatthesurveyisbeingconducted.Inthefieldoftransportation,the
revealedinformationcanincludeorigin,destination,transportmode,trippurpose,etc.Incontrast
withthestatedpreferencesurveysdescribedpreviously,theexaminedscenariosinthiscaseare
existingandnothypothetical[109].RPsurveyscanbeaddressedtousersornonusersofashared
mobilityservice.Theobjectiveistoobtainabetterunderstandingoftravelbehaviorandthe
motivationalfactorsinfluencingit.AswithSPsurveys,differenttypesofchoicemodelscanbe
appliedtothecollecteddata,whichcanleadtoindepthconclusions,e.g.,binomiallogitmodels[42],
multinomiallogitmodels[55],andmixednestedlogitmodels[53].
InthecaseofSPsurveys,theselectionofquestions,asmentionedearlier,canbedonewith
higherflexibilityasthequestionsrefertohypotheticalsituations,whereasinRPsurveysthereisless
controloverthat,astheavailablemodes/servicesisthemajordecisivefactorthatdefinesthetypeof
informationthatcanbecollected[99].Inthecontextofsharedmobility,RPsurveyscanbeusedto
examinechangesinmobilitypatterns,modalshiftdynamics,aswellastheinfluentialfactors
concerningdifferentsharedmodes/services(e.g.,see[22,91,110]).Furthermore,theimpactonpublic
transportridershipandkilometerstraveledcanbeestimatedthroughtheuseofRPdata(e.g.,see
[27]),aswellastheimpactoncarownership(e.g.,see[42]).Theresultingeffectsofsharedmobility
onVKT(e.g.,see[59,61])andonCO2emissions(e.g.,see[43])canalsobeexaminedusinganRP
survey,ascantheimpactonfirst/lastmiletrips(e.g.,see[55]).
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Itshouldbetakenintoaccountthat,fallingintothecategoryofselfreportedstudies,RPsurveys
arealsosubjecttosimilarbiasesandlimitationsastheonesalreadydiscussedforSPsurveys.
Moreover,whenRPsurveysareaddressedtousersofasharedmode,thereisalsotheriskthatthe
youngergenerationsaswellasthosewithahigherincomeareoverrepresentedinthesurvey,asthe
averageuserofsharedmobilitytendstohavetheseattributes,andthusthesurveyresultscanfailto
includevitalinputfromlargepartsofthepopulationwhodonothavetheaforementioned
characteristics[70].Notwithstandingtheselimitations,fortheforeseeablefuture,surveysare
anticipatedtomaintaintheiressentialroleinassessingthecausalfactorsrelatedtotravelbehavior
changesthatresultfromsharedmobility[48].
Thecombineduseofasurveybeforetheintroductionofanewtransportmodeandasurvey
aftertheintroductionisoftencalleda“beforeandafter”survey.Thistermcanrefereithertoastated
preferenceandarevealedpreferencesurvey(e.g.,see[53]),ortotwohousehold/mobilitytravel
surveysconductedattwodifferentperiodsintime(e.g.,see[70]).
5.2.2.AnalysisofDatafromSharedMobilityServiceProviders
Inadditiontoselfreporteddatacollectedbythesurveybasedmethodsdiscussedabove,high
qualitydatamadeavailablebymobilityserviceproviderscanbeanalyzedandinterpretedbycity
authorities.Thishasgreatpotentialintheevaluationprocessoftheimpactsofsharedmobility,asit
cancontributetotheeliminationofsomeofthelimitationsofsurveybasedmethods.Thereare
ongoingdiscussionsincitiesworldwideaboutwhethersharedmobilityserviceprovidersshouldbe
requiredtoprovidecityauthoritieswithmobilitydataandinwhichformat(standardizedornot)
thesedatashouldbepresented.
Regardingstandardizeddata,therearetwokeydataspecificationsthatmanycitiescurrently
requiretobeemployedbymobilityserviceprovidersoperatingintheirterritory:theGeneral
BikeshareFeedSpecification(GBFS)introducedin2015bytheNorthAmericanBikeshare
Association,andthemorerecentMobilityDataSpecification(MDS)createdbytheLosAngeles
DepartmentofTransportationin2018.Theyarebothbasedontheuseofapplicationprogramming
interfaces(APIs)[111].Morethan80citiesandpublicagenciesaroundtheworldarecurrentlyusing
theMDS,mostlycitiesintheU.S.,andveryrecentlysomecitiesinEuropeincludingZurich,Helsinki,
andLisbon[112].
Dataspecificationsaimtoprovideastandardizedwayformunicipalities/regulatoryagenciesto
receive,compare,andanalyzedatafrommobilityserviceproviders.However,whenitcomesto
usingamobilitydataspecification,therearesomechallengesinvolved.TheintroductionoftheMDS
hasfueledanongoingdebateabouttheprivacyofusers.Agrowingbodyofresearchdemonstrates
thatanonymousmobilitydatacanpotentiallystillbeusedtoreidentifyspecificindividualsand
activities[113,114]andtherefore,forcitiesinEuropeforinstance,compliancewiththeGeneralData
ProtectionRegulation(GDPR)shouldbethoroughlyconsideredbeforeproceedinginimplementing
adataspecification.
Anotherquestionthatarisesiswhethercityauthoritieshavetheabilityandknowledgetostoreand
analyzethedata(computer,personnel,etc.),oncetheyreceivethem,orwhethertheyneedtohire
“intermediarybodies”todealwiththeanalysisontheirbehalfandpresentthemdirectlywiththeresults.
Somestartup/mobilitydatacompanieshavealreadyexpressedinterestinactingasthe“middleman”in
suchcases.Otherreasonsfornotsupportingdatasharingcanincluderealandperceivedcompetition,
privacyandethics,theregulatoryenvironment,cybersecurity,interoperability,andliability[115].
Ifobtained,datafromsharedmobilityserviceproviderscanbeusedinvariousways.For
example,bycombiningpickupanddropoffdatafromridehailingproviderswithinformationon
trafficflow,pedestriansflow,andparking,citieswouldbeabletodynamicallymanageandregulate
theuseofstreetcurbsandpavementstolimitdwelltimesandalleviatecongestion[115].Inaddition,
bybeingabletoanalyzedatafrombikesharingprovidersandsharedmicromobilityproviders,city
authoritiescanbecomeawareofwhichpublictransportstationsattractmoreusersofsharedbikes
andsharedmicrovehicles,andthiswouldallowthemtoidentifypotentialpromisinglocationsfor
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multimodalmobilityhubsandwouldalsomagnifythepotentialofmobilityasaservice(MaaS)
applications[116].
Anotherwaythatdatafrombikesharingandsharedmicromobilityserviceproviderscanbe
usedistorevealareaswithinthecitythathaveincreasedsafetyrisks,duetothecoexistenceofa
highfrequencybuscorridorandmanyescootertrips,forinstance.Developingnewinfrastructure
solutionsintheseareastoensurethesafetyandcomfortofriderscanthenbeconsideredbythecity
authorities[116].Thecityauthorities,byhavingaccesstothedata,wouldalsobeabletoseewhether
sharedvehiclesarebeingdeployedequitablyacrossneighborhoods.Iftheyarenot,thedecision
makerscanthenplannewpoliciesincollaborationwiththesharedmobilityserviceproviders,to
promotetransportationequityinthecitybyincreasingtheavailabilityofsharedvehiclesinareas
whereunderprivilegedcommunitiesreside.Inthecaseoffreefloatingsystems,inparticular,data
fromsharedmobilityproviderscanhelpcityauthoritiesmonitorthesafetyandcomfortofvulnerable
streetusers,bycheckingifdocklessbikesandescootersareparkedinsafeandsuitableparkingareas
andnotblockingsidewalksorbikepaths,forexample[112].
5.2.3.AnalysisofotherDataSources
Therearealsosomecasesinwhichothertypesofdata(i.e.,notcomingfrommobilityservice
providers)canbeanalyzed,withmethodsthatdonotbelongtoanyofthemaincategoriesofthis
classification,thatneverthelessprovideinterestinginsightsontheimpactsofsharedmobilityand
thatcanbeusedbycitiesintheirassessmentstrategies.Someexamplesofanalysesof“otherdata”
arepresentedbelow.
AbeforeandafteranalysiswasconductedbyAmatunietal.[41]toexploretheimpactofcar
sharingonGHGemissions,inwhichtheycomparedtheoverallemissionscausedbymobilityofthe
samegroupofpeoplebeforeandaftertheystartedusingcarsharing.Theydidnotbasetheir
calculationsonselfreporteddata;instead,theyusedthelifecycleemissionfactorsforalltransport
modesandthenumberofkilometerstraveledbytheparticipantswitheachofthemforawholeyear.
Gössling[117]usedcontentanalysisofnewsitemswhichheaccessedonline,includingmaterial
publishedinnewspapers,TV,andradiowebsites,toexaminewhathappenedafteranescooter
sharedservicestartedoperatingintenlargecitiesacrosstheworld.Localmediareportsbeforeand
aftertheescooterskickedoffinthesecitieswereanalyzedandinterpretedqualitativelytosee
whethernewpoliciesforescooterswererequired.Othertypesofqualitativemethods(semi
structuredinterviewsandfocusgroups)wereusedbyJainetal.[71]tounderstandpotentialchanges
inthewaypeoplechoosetoliveandtravelwhencarsharingbecomesanoption.Asimilarapproach
comprisinginterviewswithpolicymakers,experts,researchers,andoperatorsandfocusgroupswith
driverswasappliedbyMohamedetal.[93],focusingonaridesplittingserviceinLondon.
5.3.BothExAnteandExPostEvaluation
5.3.1.HouseholdTravelSurveys/MobilitySurveys
Householdtravelsurveys(HTS)areamajorinstrumentforgatheringinformationonpassenger
traveldemandthatiscriticalforregionaltransportplanning.Suchsurveyscantakeplaceona
countryoracity/regionallevelonaregularbasis(every1,2,orsometimesmoreyears),although
therearealsoseveralcasesworldwideinwhichtheHTSdoesnotoccuratspecific,predecidedtimes
[118].Mobilitysurveysrefertoasimilarconcept;theyaremoregenericsurveysaimingtocapture
the“overallmobilitypicture”ofanarea,withquestionsthatcanincludebutarenotrestrictedto
sharedmobility.Theydifferfromhouseholdsurveysonlyinthefactthattheycanberealizedwitha
sampleunrelatedtothehouseholdasaunit(theycanbepostedonsocialmediaandaskforthe
participationofeveryinterestedperson,forexample,orbedistributedtospecificcommunities,e.g.,
studentsandemployeesofauniversity).
ThedifferencebetweenthesesurveysandtheSPandRPsurveysdiscussedaboveisthatthese
arestructuredtowardsgatheringinformationaroundaspecifictransportintervention(e.g.,the
introductionofanewsharedmobilityservice),whereasthehouseholdtravelsurveysandthe
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