Car-Sharing and Public Parking in Boston

Car-Sharing and Public Parking in Boston
by
Suthen Paradatheth
Taubman Center for State and Local Government
June 2015
Taubman Center Working Paper
WP – 2015 – 02
ExecuƟǀe ean :ohn ,aiŐh Θ ProĨessor PhiliƉ ,anser
PAC Seminar Leaders
ProĨessor :ose 'omenj-/ďanenj
PAE Adǀisor
CAR-SHARING
AND PUBLIC PARKING IN
BOSTON
^ubŵiƩed in ƉarƟal ĨulĮllŵent oĨ tŚe reƋuireŵents Ĩor tŚe deŐree
oĨ Master in Public Policy͘
Suthen Paradatheth Master in Public Policy Candidate (2015)
Policy Analysis Exercise - March 31, 2015
PreƉared Ĩor͗
Eleanor :oseƉh
Adǀisor to the Mayor, City oĨ oston Mayor͛s Kĸce
dŚis P reŇects tŚe ǀieǁs oĨ tŚe autŚor and sŚould not be ǀieǁed as reƉresenƟnŐ tŚe ǀieǁs oĨ tŚe P͛s edžternal
client͕ nor tŚose oĨ ,arǀard hniǀersity or any oĨ its Ĩaculty͘
Design by Nicholas Kang
[email protected]
over Θ /llusƚraƟon Whoƚos͗
Nicholas Kang
Car-Sharing and Public Parking in Boston
Acknowledgements
dŚis Policy nalysis džercise ǁould not Śaǀe been Ɖossible ǁitŚout tŚe ŚelƉ and suƉƉort oĨ ŵany
ƉeoƉle͘
&irst͕ / ǁould liŬe to tŚanŬ leanor :oseƉŚ͕ <ristoƉŚer Carter͕ Patricia oyleͲMc<enna͕ and tŚe staī
oĨ tŚe City oĨ oston Mayor͛s Kĸce Ĩor tŚeir Őuidance and suƉƉort tŚrouŐŚout tŚe Ɖroũect͘ / aŵ also
indebted to aniel Eunjnjo and CŚarles Śu ǁŚo Ɖroǀided tŚeir ǀaluable insiŐŚts on ƉarŬinŐ and traǀel
ƉaƩerns in oston͘
^econd͕ / ǁould liŬe to tŚanŬ Zobert Cerǀero͕ Connor 'ately͕ ^usan ^ŚaŚeen͕ daŵ CoŚen͕ ruce
<aƉlan͕ rynn >eoƉold͕ and ^aŵ iŵbabǁe Ĩor lendinŐ ŵe tŚeir Ɵŵe to discuss tŚeir oǁn ǁorŬ and
researcŚ ǁitŚ carͲsŚarinŐ as ǁell as Ɖroǀide inǀaluable ĨeedbacŬ on ŵy oǁn aƉƉroacŚes in tŚis P͘
dŚird͕ / ǁould liŬe to tŚanŬ tŚe ,arǀard <ennedy ^cŚool Ĩor tŚeir insƟtuƟonal suƉƉort͕ esƉecially
tŚrouŐŚ ŵy Ĩaculty adǀisor͕ :ose 'oŵenjͲ/banenj͕ as ǁell as tŚe PC ^eŵinar >eaders͕ :oŚn ,aiŐŚ and
PŚiliƉ ,anser͘
&ourtŚ͕ / ǁould liŬe to tŚanŬ ^Śarŵila Parŵanand͕ EicŬ <Śaǁ͕ :osŚ zardley͕ >yell ^aŬaue͕ and ,elaŚ
Zobinson Ĩor reǀieǁinŐ and ƉroǀidinŐ ĨeedbacŬ on tŚis P͘
&iŌŚ͕ / ǁould liŬe to tŚanŬ EicŚolas <anŐ Ĩor tŚe layout and desiŐn oĨ tŚis P͘
&inally͕ / ǁould liŬe to recoŐninje tŚe autŚors and contributors oĨ tŚe ĨolloǁinŐ Ĩree and oƉen source
soŌǁare ƉacŬaŐes͕ lanŐuaŐes͕ and libraries ǁŚicŚ ǁere instruŵental in ƉroducinŐ tŚe analysis in tŚis
P͗ Y'/^͕ PostŐre^Y>͕ Post'/^͕ PytŚon͕ PyscoƉŐ2͕ and Pandas͘
B O S T O N M AY O R ’ S O F F I C E
1
Car-Sharing and Public Parking in Boston
Executive Summary
CarͲsŚarinŐ orŐaninjaƟons (C^Ks) in oston are Ɖresently liŵited to ƉlacinŐ tŚeir sŚared cars in
Ɖriǀate ƉarŬinŐ sƉaces͘ ,oǁeǀer͕ tŚey Śaǀe asŬed tŚe City oĨ oston to allocate Ɖublic ƉarŬinŐ
sƉaces to tŚeir sŚared cars͘ dŚe City oĨ oston Mayor͛s Kĸce coŵŵissioned tŚis Policy nalysis
džercise to ansǁer tŚe ĨolloǁinŐ ƋuesƟon͗ ,oǁ should the City oĨ oston resƉond to the reƋuest
Ĩrom CSKs͍
dŚis decision is ŵade all tŚe ŵore diĸcult due to tŚe scarcity oĨ Ɖublic ƉarŬinŐ in ŵany Ɖarts
oĨ oston͘ ^ince residents lose a Ɖublic ƉarŬinŐ sƉace ǁŚen it is allocated to a sŚared car͕ tŚere
need to be coŵƉensaƟnŐ beneĮts to oīset tŚis added inconǀenience͘ ConseƋuently͕ in allocaƟnŐ
Ɖublic ƉarŬinŐ sƉaces to sŚared cars͕ the City oĨ oston ǁants shared cars to ďe suďsƟtutes Ĩor
Ɖriǀate ǀehicles and comƉlements to Ɖuďlic transƉortaƟon͘ dŚis broad Őoal breaŬs doǁn into tŚe
ĨolloǁinŐ sƉeciĮc Őoals (in order oĨ Ɖriority)͗
1͘ /ncrease residenƟal Ɖublic ƉarŬinŐ aǀailability
2͘ /ŵƉroǀe ŵobility access Ĩor tŚe carless
ϯ͘ Zeduce cityǁide seŚicle Miles draǀelled (sMd) and 'reenŚouse 'as (',') eŵissions
ϰ͘ Madžiŵinje city reǀenues (or ŵiniŵinje losses)
ŵƉirical researcŚ Ĩroŵ otŚer ciƟes Ɖroǀides coŵƉellinŐ eǀidence tŚat tŚese Őoals are acŚieǀable͘
dŚere is relaƟǀely stronŐ eǀidence tŚat͗
» Kne sŚared car can taŬe Ĩour Ɖriǀate ǀeŚicles oī tŚe street tŚrouŐŚ ǀeŚicle sŚeddinŐ͕ tŚus
reducinŐ ƉarŬinŐ deŵand and increasinŐ ƉarŬinŐ aǀailability͘
» ^Śared cars iŵƉroǀe tŚe ŵobility access oĨ tŚe carless͘
dŚere is also ŵodest eǀidence tŚat carͲsŚarinŐ reduces sMd and ',' eŵissions͘
dŚereĨore͕ tŚis reƉort recoŵŵends tŚat the City oĨ oston ǀieǁ car-sharinŐ as a social ďeneĮt and
allocate Ɖuďlic ƉarŬinŐ sƉaces to shared cars͘ /n doinŐ so͕ tŚe City oĨ oston sŚould͗
» stablisŚ a Ĩorŵal Ɖrocess Ĩor allocaƟnŐ Ɖublic ƉarŬinŐ sƉaces to C^Ks͘
» :ointly conduct ŵeeƟnŐs ǁitŚ C^Ks in neiŐŚborŚoods ǁŚere Ɖublic ƉarŬinŐ sƉaces ǁill be
allocated to sŚared cars͘
» ZeƋuire tŚat C^Ks sŚare releǀant data ǁitŚ tŚe City oĨ oston in order to suƉƉort its Ĩuture
allocaƟon decisions͘
'iǀen tŚe larŐe body oĨ researcŚ around its iŵƉacts͕ tŚe City oĨ oston sŚould ƉrioriƟnje allocaƟnŐ
ƉarŬinŐ sƉaces to sŚared cars in tŚe ͲtoͲ ŵodel͘ ,oǁeǀer͕ it sŚould also Ɖroceed ǁitŚ tŚe 150Ͳ
2
B O S T O N M AY O R ’ S O F F I C E
Car-Sharing and Public Parking in Boston
car Ɖilot1 oĨ tŚe ͲtoͲ ŵodel to beƩer ascertain tŚe iŵƉacts oĨ tŚis ƉroŵisinŐ innoǀaƟon in carͲ
sŚarinŐ͘
do ŵadžiŵinje tŚe beneĮts oĨ carͲsŚarinŐ͕ tŚe City oĨ oston sŚould allocate sƉaces to sŚared cars
ǁitŚin ϰ00 ŵeters oĨ areas (encaƉsulated in 250ŵdž250ŵ cells) tŚat Śaǀe͗
» More tŚan tŚree Ɖriǀately oǁned ǀeŚicles driǀen less tŚan 1ϲ ŵiles a day (see &iŐure ϴ)
» dŚe Ɖoorest access to Ɖublic transƉort as ƋuanƟĮed by an iŵŵobility score tŚat is Őreater
tŚan or eƋual to 0͘ϰ5ϳ (see &iŐure ϵ)
do striŬe a balance betǁeen coǀerinŐ tŚe city͛s costs and accruinŐ tŚe beneĮts ǁitŚ ŚiŐŚer
ƉrioriƟes͕ Ɖerŵits Ĩor tŚe ƉarŬinŐ sƉaces sŚould be Ɖriced no ŚiŐŚer tŚan tŚe Ɖrice set in tŚe
ZeƋuest Ĩor ProƉosals (Z&P)͗ Ψϯ͕500 Ɖer Ɖerŵit Ɖer year͘ s tŚe scale oĨ tŚe beneĮts is ƉroƉorƟonal
to tŚe nuŵber oĨ sŚared cars͕ tŚe City oĨ oston sŚould eǀen consider reducinŐ tŚe Ɖrice in tŚe
Ĩuture͘ dŚe Ɖerŵits sŚould be ǀalid Ĩor tǁo years͘
tŚen allocaƟnŐ addiƟonal Ɖublic ƉarŬinŐ sƉaces to sŚared cars͕ tŚe City oĨ oston sŚould adoƉt
a tŚree steƉ Ɖolicy͗ allocate͕ eǀaluate͕ and allocate aŐain͘ acŚ annual allocaƟon sŚould be
increŵental and inǀolǀe no ŵore tŚan 50 cars Ɖer C^K͘ dŚe City oĨ oston tŚen needs to eǀaluate
tŚe iŵƉacts oĨ carͲsŚarinŐ tŚrouŐŚ releǀant ŵetrics͗ tŚe nuŵber oĨ residenƟal ƉarŬinŐ Ɖerŵits
issued͕ C^K ŵeŵbersŚiƉ increases͕ ƉarŬinŐ inĨrinŐeŵents͕ and ƉeaŬͲŚour usaŐe͘ More sƉaces
sŚould only be allocated iĨ tŚe iŵƉacts are broadly ƉosiƟǀe͘
&inally͕ to edžaŵine tŚe iŵƉacts oĨ carͲsŚarinŐ in oston͕ tŚe City oĨ oston and seǀeral C^K
Ɖartners sŚould conduct tŚeir oǁn randoŵinjed study͘ dŚis study ǁill taŬe Ɖlace oǀer Ĩour years and
edžaŵines tŚe iŵƉact oĨ ŚaǀinŐ a sŚared car in close Ɖrodžiŵity on ŚouseŚold ǀeŚicle ŚoldinŐs͕ sMd
and ',' eŵissions͕ and C^K ŵeŵbersŚiƉ status͘
1 osƚon dransƉorƚaƟon DeƉarƚŵenƚ͕ ͞Driveosƚon͗ ZeƋuesƚ Ĩor WroƉosals Ĩor a osƚon sehicle ^haring Wrograŵ͕͟ &ebruary Ϯ͕ ϮϬ15͕
hƩƉs͗ͬͬƚ.coͬǁϳzZhϰϳihƉ.
B O S T O N M AY O R ’ S O F F I C E
3
Car-Sharing and Public Parking in Boston
Table of Contents
AcŬnoǁledŐements
1
ExecuƟǀe Summary
2
daďle oĨ Contents Θ &iŐures
ϰ
ChaƉter 1͗ Puďlic ParŬinŐ SƉaces Ĩor CSKs͍
ϲ
Car-sharing
6
Status of Car-sharing in Boston
7
CitLJ of Boston anĚ thĞ DaLJor͛s KĸĐĞ
ϴ
WuďůiĐ WarŬing SƉaĐĞ dLJƉĞs
ϴ
ChaƉter 2͗ 'oals
ϵ
/nĐrĞasing ZĞsiĚĞnƟaů WuďůiĐ WarŬing ǀaiůaďiůitLJ
ϭϬ
/ŵƉroǀĞ DoďiůitLJ ĐĐĞss
ϭϬ
ZĞĚuĐĞ sĞhiĐůĞ DiůĞs draǀĞůůĞĚ anĚ 'rĞĞnhousĞ 'as ŵissions
ϭϮ
/nĐrĞasĞ ZĞǀĞnuĞ ;or DiniŵinjĞ >ossĞsͿ for thĞ CitLJ of Boston
ϭϮ
'oaů WrioriƟĞs
ϭϰ
ChaƉter 3͗ /mƉacts oĨ Car-SharinŐ
15
ǀaůuaƟng thĞ ŵƉiriĐaů ZĞsĞarĐh on Car-sharing
ϭ7
WriǀatĞ sĞhiĐůĞ KǁnĞrshiƉ
ϭϵ
DoďiůitLJ ĐĐĞss
ϮϬ
sĞhiĐůĞ DiůĞs draǀĞůůĞĚ ;sDdͿ anĚ 'rĞĞnhousĞ 'as ;','Ϳ ŵissions
ϮϬ
ZĞǀĞnuĞ anĚ thĞ SharĞĚ Car WarŬing WĞrŵit WriĐĞ
ϮϮ
ConĐůusion
ϮϮ
ChaƉter ϰ͗ ZecommendaƟons
4
2ϰ
ZĞĐoŵŵĞnĚaƟon ϭ͗ ůůoĐatĞ WuďůiĐ WarŬing SƉaĐĞs to SharĞĚ Cars
Ϯϰ
ZĞĐoŵŵĞnĚaƟon Ϯ͗ ConĚuĐt an /nĚĞƉĞnĚĞnt /ŵƉaĐt StuĚLJ
Ϯϵ
B O S T O N M AY O R ’ S O F F I C E
Car-Sharing and Public Parking in Boston
Table of Contents
AƉƉendices
31
ƉƉĞnĚidž ͗ Boston EĞighďorhooĚs
ϯϮ
ƉƉĞnĚidž B͗ Car-sharing KrganinjaƟons ;CSKsͿ
33
ƉƉĞnĚidž C͗ ,ousĞhoůĚs anĚ sĞhiĐůĞ KǁnĞrshiƉ
3ϰ
ƉƉĞnĚidž ͗ StuĚiĞs on /ŵƉaĐts of Car-Sharing
36
ƉƉĞnĚidž ͗ ĞtaiůĞĚ ZĞǀiĞǁ of ShortůistĞĚ StuĚiĞs on /ŵƉaĐts of Car-sharing
37
ƉƉĞnĚidž &͗ WrĞĚiĐƟǀĞ DoĚĞů on ChangĞs in sĞhiĐůĞ KǁnĞrshiƉ for CitLJ CarSharĞ
ϰϬ
ƉƉĞnĚidž '͗ ĞtĞrŵining DoďiůitLJ SĐorĞs
ϰϭ
ƉƉĞnĚidž ,͗ StuĚLJ WrotoĐoů to džaŵinĞ thĞ /ŵƉaĐts of Car-Sharing in Boston
ϰϮ
&iŐures
&igurĞ ϭ͗ WassĞngĞr ǀĞhiĐůĞ Đounts
&igurĞ Ϯ͗ DoďiůitLJ sĐorĞs
&igurĞ 3͗ WotĞnƟaů iŵƉaĐts of aůůoĐaƟng ƉuďůiĐ ƉarŬing to sharĞĚ Đars
&igurĞ ϰ͗ /ŵƉaĐts on ƉriǀatĞ ǀĞhiĐůĞ oǁnĞrshiƉ anĚ ƉuďůiĐ ƉarŬing aǀaiůaďiůitLJ
&igurĞ ϱ͗ /ŵƉaĐts on ŵoďiůitLJ aĐĐĞss
&igurĞ 6͗ /ŵƉaĐts on sDd anĚ ',' Ğŵissions
&igurĞ 7͗ /ŵƉaĐt of ƉĞrŵit ƉriĐĞs
&igurĞ ϴ͗ sĞhiĐůĞs ǁith ůoǁ ŵiůĞagĞ ;ďĞůoǁ ϭ6 ŵiůĞs ƉĞr ĚaLJͿ in a ĐĞůů
&igurĞ ϵ͗ /ŵŵoďiůitLJ sĐorĞs
&igurĞ ϭϬ͗ CitLJ of Boston nĞighďorhooĚs
&igurĞ ϭϭ͗ sĞhiĐůĞs ƉĞr housĞhoůĚ
&igurĞ ϭϮ͗ EuŵďĞr of housĞhoůĚs in a ĐĞůů
&igurĞ ϭ3͗ ϮϱϬŵdžϮϱϬŵ ĐĞůůs for Boston
B O S T O N M AY O R ’ S O F F I C E
ϭϭ
ϭ3
ϭ6
ϭϴ
ϭϵ
ϮϬ
Ϯϭ
Ϯ7
Ϯϴ
3Ϯ
3ϰ
3ϱ
ϰϰ
5
Car-Sharing and Public Parking in Boston
Chapter 1:
Public Parking Spaces for CSOs?
ƵƌƌĞŶƚůLJ͕ĐĂƌͲƐŚĂƌŝŶŐŽƌŐĂŶŝnjĂƟŽŶƐ;^KƐͿŽƉĞƌĂƟŶŐ
ŝŶŽƐƚŽŶĂƌĞůŝŵŝƚĞĚƚŽƵƐŝŶŐŽŶůLJƉƌŝǀĂƚĞƉĂƌŬŝŶŐ
ƐƉĂĐĞƐĨŽƌůŽĐĂƟŶŐƚŚĞŝƌĐĂƌƐ͘/ŶƚĞƌĞƐƚĞĚŝŶĞdžƉĂŶĚŝŶŐ
ƚŚĞŝƌŶĞƚǁŽƌŬƐ͕ƚŚĞƐĞ^KƐŚĂǀĞĂƐŬĞĚƚŚĂƚƚŚĞŝƚLJ
ŽĨŽƐƚŽŶĂůůŽǁƚŚĞŵƚŽƵƐĞƉƵďůŝĐƉĂƌŬŝŶŐƐƉĂĐĞƐ
ĂƐǁĞůů͘^ŚŽƵůĚƚŚĞŝƚLJŽĨŽƐƚŽŶĂůůŽĐĂƚĞƐŽŵĞŝƚƐ
ŽǀĞƌƐƵďƐĐƌŝďĞĚƉƵďůŝĐƉĂƌŬŝŶŐƐƉĂĐĞƐĨŽƌĞdžĐůƵƐŝǀĞ
ƵƐĞďLJĐĂƌͲƐŚĂƌŝŶŐŽƌŐĂŶŝnjĂƟŽŶƐ;^KƐͿ͍/ĨƐŽ͕ǁŚĂƚ
ĂůůŽĐĂƟŽŶƉŽůŝĐLJƐŚŽƵůĚďĞĂĚŽƉƚĞĚƐƵĐŚƚŚĂƚŝƚ
ƉƌŽǀŝĚĞƐƚŚĞŵŽƐƚǀĂůƵĞƚŽƚŚĞĐŝƚLJĂŶĚŝƚƐƌĞƐŝĚĞŶƚƐ͍
&ŽƌƚŚĞŝƚLJŽĨŽƐƚŽŶ͕ƚŚŝƐŝƐƐƵĞŝƐĞƐƉĞĐŝĂůůLJ
ĐŽŶƚĞŶƟŽƵƐďĞĐĂƵƐĞƚŚĞƌĞŝƐŝŶƐƵĸĐŝĞŶƚƉƵďůŝĐ
ƉĂƌŬŝŶŐĨŽƌƌĞƐŝĚĞŶƚƐ͘
Car-sharing
CarͲsŚarinŐ Ɖroǀides onͲdeŵand access to a Ňeet
oĨ cars Ĩor sŚortͲterŵ rental͕ oŌen in increŵents
oĨ an Śour or less͘ do access a car͕ ŵeŵbers ŵust
be aĸliated ǁitŚ tŚe C^K tŚat ŵanaŐes it͘ dŚese
orŐaninjaƟons can be eitŚer ĨorͲ or nonͲƉroĮt͘ dŚe
sŚared cars are oŌen disƉersed in decentralinjed
netǁorŬs and are selĨͲaccessinŐ͕ usually ǀia a ǁireless
6
Ŭeycard (i͘e͘ no Śandoǀer oĨ Ŭeys is reƋuired)͘2
ZeserǀaƟons are ŵade in adǀance͕ usually ǀia tŚe
ǁeb or a sŵartƉŚone aƉƉlicaƟon͘ eƉendinŐ on tŚe
ŵodel oĨ tŚe C^K͕ users are cŚarŐed based on tŚe
duraƟon oĨ tŚeir usaŐe͕ duraƟon oĨ tŚeir reserǀaƟon͕
distance traǀelled͕ or soŵe ŵidž oĨ tŚese tŚree͘ hsaŐe
cŚarŐes are ŵade to tŚe ŵeŵber͛s credit card or
deducted Ĩroŵ tŚeir banŬ account͘ MeŵbersŚiƉ in
a C^K includes Ĩull liability and collision coǀeraŐe ǀia
tŚe C^K͛s insurance Ɖolicy͖ ŵeŵbers do not need to
ƉurcŚase tŚeir oǁn insurance͘3
dŚere are tǁo ŵodels oĨ locaƟnŐ cars tŚat C^Ks
use͕ ǁŚicŚ also inŇuence tŚe nature oĨ tŚe triƉs by
members:
» A-to-A or dǁo-ǁay͗ dŚis is a more tradiƟonal
model ǁŚere sŚared cars are located at
desiŐnated ƉarŬinŐ sƉaces͕ reĨerred to as stalls
Ϯ daŵ DillardͲall͕ dCZW ZĞƉort ϭϬϴ͗ Car-Sharing͗ thĞrĞ anĚ ,oǁ /t
SuĐĐĞĞĚs͕ vol. 1Ϭϴ ;dransƉorƚaƟon Zesearch oard͕ ϮϬϬ5Ϳ.
ϯ daŵ W. ohen͕ ^usan ^haheen͕ and Zyan DcKennjie͕ ͞arsharing͗ 'uide
Ĩor >ocal Wlanners͕͟ /nsƟtutĞ of dransƉortaƟon StuĚiĞs͕ Deceŵber 1͕ ϮϬϬϴ͕
hƩƉ͗ͬͬescholarshiƉ.orgͬucͬiƚeŵͬϰkĨϯdžϯ1h.
B O S T O N M AY O R ’ S O F F I C E
Car-Sharing and Public Parking in Boston
or ƉointsͲoĨͲdeƉarture (PKs)͘ driƉs ǁitŚ tŚe
sŚared car must beŐin and end at its desiŐnated
PK͘ car must be returned to its PK ǁitŚin
tŚe reserǀaƟon Ɖeriod or lateͲƉenalƟes are
aƉƉlied by tŚe C^K͘
» A-to- or Point-to-Ɖoint or Kne-tay͗ This is a
neǁer model ǁhere shared cars do not haǀe
desiŐnated ƉarŬinŐ sƉaces͘ TriƉs can beŐin and
end in any ƉarŬinŐ sƉace͕ thouŐh the C^K oŌen
limits these sƉaces to certain ŐeoŐraƉhical
njones based on their area oĨ oƉeraƟon and
their arranŐements ǁith the municiƉality (e͘Ő͘
ǁithin city limits but edžcludinŐ the central
business district)͘ Members do not haǀe to
Ɖay ƉarŬinŐ charŐes Ĩor the sƉaces ǁhere they
terminate their triƉs͘ CharŐes are based on the
duraƟon the shared car is in use and members
oŌen locate a car ǁith the aid oĨ a smartƉhone
aƉƉlicaƟon͘
esides hoǁ the cars located͕ there are diīerent
models oĨ Ňeet oǁnershiƉ:
» CSK-oǁned͗ /n this more tradiƟonal model͕
the shared cars are oǁned by the C^K͘ esides
insurance͕ Ĩuel costs are coǀered by the C^K and
included in the charŐe͘
» Peer-to-Ɖeer͗ /n this emerŐinŐ model͕ the cars
are Ɖriǀately oǁned and the C^K serǀes as an
intermediary betǁeen the user and the oǁner
oĨ the car͘ This model tends to be ͲtoͲ as the
shared car has to be taŬen Ĩrom and returned
to the oǁner͛s Ɖriǀate ƉarŬinŐ sƉace (e͘Ő͘ their
driǀeǁay)͘ thile insurance is sƟll Ɖroǀided͕
edžƉenses Ĩor Ĩuel are borne by the user oĨ the
car͘
The term ͞car͟ ǁith reĨerence in ͞carͲsharinŐ͟ is
misleadinŐ as the ǀehicles include cars͕ trucŬs͕ and
ǀans͘
thile there are many similariƟes͕ carͲsharinŐ diīers
Ĩrom the tradiƟonal carͲrental model in the ĨolloǁinŐ
ǁays:
» uraƟon oĨ rental͗ ^hared cars are oŌen rented
on an hourly basis as oƉƉosed to a daily basis͘
» ecentralinjaƟon͗ ^hared cars are disƉersed
in small numbers throuŐhout a ŐeoŐraƉhic
locaƟon͕ oŌen a city͕ ǁhereas rental cars tend to
B O S T O N M AY O R ’ S O F F I C E
be concentrated in larŐe numbers in a rental car
lot͘
» AutomaƟon͗ TransacƟons inǀolǀinŐ shared cars
reƋuire ǀery liƩle human interǀenƟon Ĩrom the
C^K because reserǀaƟons͕ car access͕ tracŬinŐ͕
and billinŐ are automated͘ /n contrast͕ a rental
car inǀolǀes manual Ŭey handoǀer and ƉostͲ
usaŐe insƉecƟon by the rental comƉany͘
tyƉical usaŐeͲscenario oĨ a shared car is as Ĩolloǁs:
ŵĞŵďĞr of a CSK ŵaŬĞs a onĞ-hour rĞsĞrǀaƟon
for a sharĞĚ Đar ǁith a WK in a ƉarŬing ůot nĞar hĞr
aƉartŵĞnt at 3WD͘ t 3͗ϬϱWD͕ shĞ ǁaůŬs uƉ to thĞ
rĞsĞrǀĞĚ Đar anĚ aĐĐĞssĞs it using a ǁirĞůĞss ŬĞLJĐarĚ
that is giǀĞn to ŵĞŵďĞrs of thĞ CSK͘ ShĞ ĚriǀĞs to
a groĐĞrLJ storĞ thrĞĞ ŵiůĞs froŵ hĞr aƉartŵĞnt͕
ƉurĐhasĞs hĞr groĐĞriĞs for thĞ ǁĞĞŬ͕ ůoaĚs thĞŵ into
thĞ Đar͕ anĚ thĞ ŵaŬĞs thĞ rĞturn triƉ͘ t 3͗ϱϱWD͕ shĞ
ƉarŬs thĞ Đar in thĞ WK shĞ tooŬ it froŵ anĚ ůoĐŬs
it using thĞ ǁirĞůĞss ŬĞLJĐarĚ͘ KnďoarĚ ĞůĞĐtroniĐs
instaůůĞĚ ďLJ thĞ CSK in thĞ sharĞĚ Đar ǀĞrifLJ that thĞ
ĚistanĐĞ traǀĞůůĞĚ is ǁithin thĞ frĞĞ aůůotŵĞnt giǀĞn to
ŵĞŵďĞr ƉĞr rĞsĞrǀaƟon anĚ that it has ďĞĞn rĞturnĞĚ
to its ĚĞsignatĞĚ WK͘ dhĞ Đar is noǁ aǀaiůaďůĞ for
anothĞr rĞsĞrǀaƟon͘
/n 201ϰ͕ there ǁere ϰ5 C^Ks oƉeraƟnŐ in the hnited
^tates ǁith oǀer 1͘ϲ million C^K members and 2ϰ͕000
ǀehicles͘4 ƉƉendidž : CarͲsharinŐ KrŐaninjaƟons (C^Ks)
Ɖroǀides a list oĨ carͲsharinŐ orŐaninjaƟons and the
models that they use͘
Status of Car-sharing in Boston
CarͲsharinŐ has been established in oston Ĩor oǀer a
decade͘ iƉcar͕ one oĨ the larŐest C^Ks͕ ǁas Ĩounded in
the year 2000 in CambridŐe͕ a city adũacent to oston͕
and is currently headƋuartered in oston͘ /n the Ĩourth
Ƌuarter oĨ 2013͕ iƉcar had an esƟmated 3ϴ͕0ϲ5
members and 1ϳϴ ǀehicles ǁithin the city͛s limits͘5
/n addiƟon to iƉcar͕ nterƉrise and Zelay Zides also
oƉerate in oston͘
Eone oĨ the shared cars are Ɖlaced in the Ɖublic
ƉarŬinŐ sƉaces oǁned by the City oĨ oston͘ C^Ks use
Ɖriǀate ƉarŬinŐ sƉaces instead͘ These include Ɖriǀate
ϰ ^usan ^haheen and daŵ ohen͕ Carsharing KutůooŬ &aůů ϮϬϭϰ - soůuŵĞ 3͕
/ssuĞ Ϯ͕ Noveŵber 11͕ ϮϬ1ϰ͕ hƩƉ͗ͬͬƚsrc.berkeley.eduͬsiƚesͬƚsrc.berkeley.eduͬ
Įlesͬ&allйϮϬϮϬ1ϰйϮϬarsharingйϮϬKuƚlookйϮϬ&inal.ƉdĨ.
5 ϯϳ illion Dile hallenge͕ ͞ϯϳ illion Dile hallenge͗ Daƚaƚhon dreaƚ͕͟
Darch 1Ϭ͕ ϮϬ1ϰ͕ hƩƉ͗ͬͬǁǁǁ.ϯϳbillionŵilechallenge.orgͬηƚheͲdaƚa.
7
Car-Sharing and Public Parking in Boston
ƉarŬinŐ ŐaraŐes as ǁell as Ɖriǀate lots belonŐinŐ to
residenƟal and commercial buildinŐs͘ ,oǁeǀer͕ the
hiŐh Ɖrice and limited suƉƉly oĨ Ɖriǀate ƉarŬinŐ sƉace
limits the number oĨ shared cars that C^Ks can locate
in oston and thus͕ the sinje oĨ their netǁorŬs͘
The Mayor͛s Kĸce oǀersees the Ŭey ĨuncƟons oĨ
Ɖolicy deǀeloƉment and manaŐement ƉlanninŐ͘ tith
a small staī͕ it serǀes tǁo roles: desiŐninŐ Ɖolicy
and imƉlementaƟon strateŐies Ĩor the Mayor and
coordinaƟnŐ the ǁorŬ oĨ the ǀarious city deƉartments͘
The City oĨ oston recently released a ZeƋuest Ĩor
ProƉosals (Z&P) inǀiƟnŐ C^Ks to aƉƉly Ĩor Ɖublic ƉarŬinŐ
sƉaces in a Ɖilot ƉroŐram͘ϲ The Z&P ǁas deǀeloƉed in
Ɖarallel ǁith this reƉort and incorƉorates some oĨ its
Ɖreliminary ĮndinŐs͘
This ǁorŬ is comƉlemented by oston͛s Mayor͛s Kĸce
oĨ Eeǁ hrban Mechanics (MKEhM)͘ &ormed in 2010͕
oston͛s MKEhM serǀes as the Mayor͛s innoǀaƟon
ŐrouƉ͘ /t collaborates ǁith consƟtuents͕ academics͕
entreƉreneurs͕ nonͲƉroĮts and city staī to desiŐn͕
conduct͕ and eǀaluate Ɖilot Ɖroũects that imƉroǀe the
Ƌuality oĨ city serǀices͘ These Ɖroũects are in Ĩour maũor
issue areas: ducaƟon͕ nŐaŐement͕ the ^treetscaƉe͕
and conomic eǀeloƉment͘
&or the Ɖilot͕ the city is oīerinŐ a total oĨ ϴ0 edicated
Permits Ĩor the creaƟon oĨ ͲtoͲ model shared car
PKs͘ edicated Permits allocate a Ɖublic ƉarŬinŐ
sƉace to a sƉeciĮc C^K͛s shared car͘ sinŐle C^K can
hold no more than 40 edicated Permits͘ /n order
to Ɖilot the ͲtoͲ model͕ 150 &reeͲŇoaƟnŐ ParŬinŐ
Permits are beinŐ oīered͘ shared car ǁith a &reeͲ
ŇoaƟnŐ ParŬinŐ Permit can be ƉarŬed in any leŐal
Ɖublic ƉarŬinŐ sƉace͘ ddiƟonally͕ the shared car and
motorist are not subũect to meter Ɖayment or Ɵme
limit and residenƟal ƉarŬinŐ Ɖermit restricƟons͘ Knly a
sinŐle C^K ǁill be Őranted these &reeͲŇoaƟnŐ ParŬinŐ
Permits͘ϳ
City of Boston and the Mayor’s
1fƂEe
Kǀer ϲ1ϳ͕000 residents distributed across 23
neiŐhborhoods call oston their home (see &iŐure 10
in ƉƉendidž : oston EeiŐhborhoods)͘ The City oĨ
oston municiƉal Őoǀernment serǀes these residents
as ǁell as 5ϲ͕000 Ɖublic school students͕ hundreds oĨ
thousands oĨ ƉeoƉle ǁorŬinŐ in the city eǀery day͕ and
tens oĨ millions oĨ ǀisitors and tourists annually͘
2uDNiE 2arMing SRaEe 6yRes
There are three Ɖrimary tyƉes oĨ Ɖublic ƉarŬinŐ sƉaces
in oston that are under consideraƟon Ĩor allocaƟon to
C^Ks:
» Kn-Street͗ These are curbside ƉarŬinŐ sƉaces
that are usually used by residenƟal Ɖermit
holders͘
» Metered͗ Metered onͲstreet ƉarŬinŐ sƉaces
ǁhich are usually Ĩound in commercial districts͘
» MuniciƉal Lots͗ ParŬinŐ lots oǁned by the City
oĨ oston that Ɖroǀide Ĩree ƉarŬinŐ sƉaces Ĩor
anyone͘
The municiƉal Őoǀernment is comƉrised oĨ ϳ0
indiǀidual aŐencies͕ commissions and deƉartments
ǁith more than 1ϲ͕000 emƉloyees͘ /t is orŐaninjed in a
tradiƟonal cabinet structure and its maũor ĨuncƟonal
areas include manaŐinŐ Ɖublic schools͖ ensurinŐ
Ɖublic saĨety͖ sƟmulaƟnŐ economic͕ housinŐ and
neiŐhborhood deǀeloƉment͖ coordinaƟnŐ human
serǀices ƉroŐrams Ĩor consƟtuents oĨ all aŐes͖ ƉroǀidinŐ
necessary inĨrastructure and basic city serǀices to
residents and suƉƉorƟnŐ the oƉeraƟons oĨ all line
deƉartments͘
ϲ osƚon dransƉorƚaƟon DeƉarƚŵenƚ͕ ͞Driveosƚon͗ ZeƋuesƚ Ĩor WroƉosals
Ĩor a osƚon sehicle ^haring Wrograŵ.͟
ϳ /bid.
8
B O S T O N M AY O R ’ S O F F I C E
Car-Sharing and Public Parking in Boston
Chapter 2:
Goals
A
>>KCT/E' Ɖublic ƉarŬinŐ sƉaces to shared
cars leaǀes Ĩeǁer sƉaces Ĩor oston͛s residents
to use Ĩor their oǁn ǀehicles͘ s Ɖublic
ƉarŬinŐ is already scarce in many Ɖarts oĨ the city͕ this
chaƉter idenƟĮes the beneĮcial outcomes that ǁould
comƉensate Ĩor this added inconǀenience͘ ThereĨore͕
in allocaƟnŐ Ɖublic ƉarŬinŐ sƉaces Ĩor use by carͲ
sharinŐ orŐaninjaƟons (C^Ks)͕ the City oĨ oston seeŬs
the ĨolloǁinŐ broad outcome: that shared cars ďecome
suďsƟtutes Ĩor Ɖriǀate ǀehicles and comƉlements to
Ɖuďlic transƉortaƟon͘
This oǀerarchinŐ Őoal is deriǀed Ĩrom seǀeral smaller
Őoals͘ &irst͕ the City oĨ oston seeŬs to maŬe ƉarŬinŐ
easier Ĩor its residents by increasinŐ residenƟal
Ɖuďlic ƉarŬinŐ aǀailaďility͘ ^econd͕ oston seeŬs to
imƉroǀe the moďility choice and access oĨ residents
ǁho do not oǁn their oǁn ǀehicle͘ Third͕ in order to
meet the commitments set out in its Climate cƟon
Plan͕ the City oĨ oston seeŬs to reduce ǀehicle-miles
traǀelled ;sMdͿ and Őreenhouse Őas ;','Ϳ emissions͘
&inally͕ the City oĨ oston ǁishes to Őain a neǁ source
oĨ reǀenue or, at ǁorst, miniminje the losses Ĩrom
allocaƟnŐ these sƉaces to shared cars͘ The City oĨ
B O S T O N M AY O R ’ S O F F I C E
oston͛s decision on ǁhether and hoǁ to allocate
Ɖublic ƉarŬinŐ sƉaces to C^Ks ǁill be driǀen by the
deŐree to ǁhich these Őoals are met͘ϴ
esides the Őoals aboǀe͕ the recently released ZeƋuest
Ĩor ProƉosals (Z&P) contained tǁo addiƟonal Őoals:
increasinŐ transƉortaƟon oƉƟons at Mobility ,ubs and
to suƉƉort main street districts͘ϵ Mobility ,ubs are Ɖart
oĨ the oston ComƉlete ^treets 'uidelines and seeŬ to
brinŐ toŐether seǀeral modes oĨ transƉort at a sinŐle
curbside locaƟon͘10 &or edžamƉle͕ a MassachuseƩs ay
TransƉortaƟon uthority (MT) staƟon ǁould haǀe
a shared car͕ bus stoƉ͕ and biŬeͲsharinŐ racŬ in close
Ɖrodžimity͘ tith the main street districts͕ the City oĨ
oston seeŬs to use carͲsharinŐ to increase the amount
oĨ acƟǀity in seǀeral main street commercial areas (i͘e͘
udley͕ riŐhton͕ 'roǀer ,all͕ and :amaica Plainͬ^outh
ϴ dhese goals ǁere generaƚed ƚhrough conversaƟons ǁiƚh ƚhe clienƚ over ƚhe
course oĨ coŵƉleƟng ƚhis reƉorƚ.
ϵ osƚon dransƉorƚaƟon DeƉarƚŵenƚ͕ ͞Driveosƚon͗ ZeƋuesƚ Ĩor WroƉosals
Ĩor a osƚon sehicle ^haring Wrograŵ.͟
1Ϭ osƚon dransƉorƚaƟon DeƉarƚŵenƚ͕ ͞osƚon oŵƉleƚe ^ƚreeƚs͗ 5.ϯ͗
Dobiliƚy ,ubs͕͟ in Boston CoŵƉůĞtĞ StrĞĞts 'uiĚĞůinĞs͕ accessed &ebruary
11͕ ϮϬ15͕ hƩƉ͗ͬͬissuu.coŵͬbosƚonƚransƉorƚaƟondeƉarƚŵenƚͬdocsͬ5_ϯ.
9
Car-Sharing and Public Parking in Boston
Main ^treets)͘ These addiƟonal Őoals are not edžamined
seƉarately in this reƉort as they larŐely oǀerlaƉ ǁith
the Őoals oĨ reducinŐ ƉarŬinŐ demand and imƉroǀinŐ
mobility access͘
+nEreasing 4esidentiaN 2uDNiE 2arMing
Availability
/n many Ɖarts oĨ oston͕ the demand Ĩor residenƟal
onͲstreet Ɖublic ƉarŬinŐ sƉaces outstriƉs the suƉƉly͘
The Ɖroblem is made more intractable by the absence
oĨ an onͲstreet sƉace inǀentory: the City oĨ oston does
not Ŭnoǁ hoǁ many onͲstreet Ɖublic ƉarŬinŐ sƉaces
(includinŐ those used by residents) it has or ǁhere they
are͘ Thus͕ oston has no ǁay oĨ ŬnoǁinŐ the onͲstreet
ƉarŬinŐ suƉƉly shorƞall͘
ue to the shortaŐe oĨ sƉaces͕ residents haǀe reƉorted
sƉendinŐ siŐniĮcant amounts oĨ Ɵme searchinŐ Ĩor
a ƉarŬinŐ sƉace͘11 eyond the Ɵme cost borne by
residents͕ this also introduces costs on others (i͘e͘
edžternaliƟes) throuŐh increased traĸc conŐesƟon and
ƉolluƟon͘ CruisinŐ Ĩor ƉarŬinŐ has been reƉorted to
account Ĩor uƉ to 30й oĨ total traĸc in city centers͘12
The oǀersubscriƉƟon oĨ Ɖublic ƉarŬinŐ is more acute
in areas ǁith hiŐh ƉoƉulaƟon densiƟes (&iŐure 12 in
ƉƉendidž C: ,ouseholds and sehicle KǁnershiƉ)͘
The darŬ red cells in &iŐure 1 reƉresent 250 by 250
meter ŐeoŐraƉhical areas (i͘e͘ 250mdž250m cells)
ǁhere ƉarŬinŐ demand is edžƉected to be the hiŐhest͘
PassenŐer ǀehicle counts in these cells are in the uƉƉer
ƋuarƟle oĨ all cells in oston͘
n edžaminaƟon oĨ oston͛s Ɖublic ƉarŬinŐ Ɖolicy
reǀeals the source oĨ the Ɖroblem: the city neither
charŐes Ĩor nor limits the number oĨ Ɖermits that it
issues to residents desƉite there beinŐ limited onͲ
street sƉaces͘ resident can Őet a Ĩree ƉarŬinŐ Ɖermit͕
ǀalid Ĩor tǁo years͕ Ĩor eǀery ǀehicle they oǁn͘ These
Ɖermits alloǁ holders to leŐally ƉarŬ in onͲstreet sƉaces
ǁithin their desiŐnated residenƟal njones͘ ,oǁeǀer͕
there is no Őuarantee that the holder ǁill Įnd a sƉace͘13
s oĨ 2015͕ oston has ϵ3͕ϵϴϳ acƟǀe residenƟal
ƉarŬinŐ Ɖermits͘14 The aǀeraŐe household in oston
oǁns 0͘ϳ3 cars͘15 &iŐure 11 (in ƉƉendidž C: ,ouseholds
and sehicle KǁnershiƉ) shoǁs the aǀeraŐe number
oĨ ǀehicles Ɖer household Ĩor each oĨ the city͛s cells͘
ThouŐh most households only hold one Ɖermit͕ 300
ǁere Ĩound to haǀe Įǀe or more͘ Kne household ǁas
Ĩound to hold eleǀen Ɖermits͘1ϲ
hnƟl recently͕ city oĸcials and many residents haǀe
deĨended the system͘ ,oǁeǀer͕ the neǁlyͲaƉƉointed
TransƉortaƟon Commissioner͕ 'ina &iandaca͕ has said
the she ǁill reͲedžamine the edžisƟnŐ Ɖrocess͘1ϳ
MarŬet mechanisms could Ɖroǀide a ĮrstͲorder soluƟon
to the oǀersubscriƉƟon oĨ Ɖublic ƉarŬinŐ sƉaces͘ /n
one Ɖossible imƉlementaƟon͕ residenƟal Ɖermits could
be sold throuŐh an aucƟon͘ The Ɖrice buyers ǁould
be ǁillinŐ to Ɖay is a ĨuncƟon oĨ the uƟlity they deriǀe
Ĩrom haǀinŐ the riŐht to use a Ɖublic ƉarŬinŐ sƉace͕
ǁhich ǁould include the Ɖrobability oĨ beinŐ able to
Įnd a sƉace͘ ǀentually͕ the ƋuanƟty oĨ Ɖublic ƉarŬinŐ
sƉaces demanded ǁould aƉƉrodžimate the suƉƉly͘
,oǁeǀer͕ this Ɖolicy is liŬely to be unƉoƉular ǁith
oston residents͘ CaƉs on the number oĨ Ĩree Ɖermits
Ɖer household are an alternaƟǀe soluƟon thouŐh
this comes ǁith its oǁn Ɖiƞalls͘ ChieĨ amonŐ these is
the inability to accurately determine a caƉ ǁithout
ŬnoǁinŐ the total number oĨ Ɖublic ƉarŬinŐ sƉaces͘
/n liŐht oĨ all this͕ allocaƟnŐ Ɖublic ƉarŬinŐ sƉaces to
shared cars is liŬely to be ǁell receiǀed iĨ it reduces
the demand Ĩor ƉarŬinŐ͕ thus increasinŐ Ɖublic ƉarŬinŐ
aǀailability͘ The nedžt chaƉter oĨ this reƉort assesses
the ƉotenƟal Ĩor carͲsharinŐ to reduce ƉarŬinŐ demand
throuŐh reducƟons in ǀehicle oǁnershiƉ͘
+ORrove Mobility AEEess
ƉƉrodžimately 34й oĨ oston͛s 251͕ϳ5ϳ households
do not oǁn a car͘1ϴ Members oĨ these households
rely on other modes oĨ transƉortaƟon liŬe ǁalŬinŐ͕
1ϰ /bid.
15 diŵ Zeardon eƚ al.͕ sĞhiĐůĞ CĞnsus of DassaĐhusĞƩs͕ sehicle ensus
;DeƚroƉoliƚan rea Wlanning ouncil͕ Darch 1Ϭ͕ ϮϬ1ϰͿ.
1ϲ tallack͕ ͞osƚon Ͷ there Warking /s ^carce͕ buƚ Warking Werŵiƚs re &ree
and hnliŵiƚed.͟
11 dodd tallack͕ ͞osƚon Ͷ there Warking /s ^carce͕ buƚ Warking Werŵiƚs
re &ree and hnliŵiƚed͕͟ dhĞ Boston 'ůoďĞ͕ :anuary ϮϬ͕ ϮϬ15.
1Ϯ ^iŵon W. nderson and ndrĠ de Walŵa͕ ͞dhe conoŵics oĨ Wricing
Warking͕͟ :ournaů of hrďan ĐonoŵiĐs 55͕ no. 1 ;:anuary ϮϬϬϰͿ͗ 1ʹϮϬ.
1ϯ tallack͕ ͞osƚon Ͷ there Warking /s ^carce͕ buƚ Warking Werŵiƚs re &ree
and hnliŵiƚed.͟
10
1ϳ dodd tallack͕ ͞osƚon soǁs ƚo džaŵine Warking Zules Ĩor Zesidenƚs͕͟
dhĞ Boston 'ůoďĞ͕ :anuary Ϯϲ͕ ϮϬ15͕ hƩƉs͗ͬͬǁǁǁ.bosƚonglobe.
coŵͬŵeƚroͬϮϬ15ͬϬ1ͬϮϲͬbosƚonͲvoǁsͲedžaŵineͲƉarkingͲrulesͲĨorͲ
residenƚsͬϬ1dϵ,ϬƉn:kZyrKdž:,njnϵr:ͬsƚory.hƚŵl.
1ϴ h.^. ensus ureau͕ WϬϰ - S>Cd ,KhS/E' C,ZCdZ/Sd/CS͕ ϮϬ1ϯ
ŵerican oŵŵuniƚy ^urvey 1Ͳzear sƟŵaƚes͕ n.d.͕ hƩƉ͗ͬͬĨacƞinder.census.
govͬbkŵkͬƚableͬ1.Ϭͬenͬ^ͬ1ϯ_1zZͬDWϬϰͬ1ϲϬϬϬϬϬh^Ϯ5ϬϳϬϬϬ.
B O S T O N M AY O R ’ S O F F I C E
Car-Sharing and Public Parking in Boston
FIGURE 1: PASSENGER VEHICLE COUNTS
B O S T O N M AY O R ’ S O F F I C E
11
Car-Sharing and Public Parking in Boston
biŬinŐ͕ Ɖublic transit͕ tadžis͕ and transƉortaƟon netǁorŬ
comƉanies (e͘Ő͘ hber and >yŌ) Ĩor their mobility͘ CarͲ
sharinŐ can comƉlement these modes and imƉroǀe the
oǀerall uƟlity oĨ carless households by edžƉandinŐ their
consumƉƟon set͘ &or edžamƉle͕ a shared car can be
used to maŬe triƉs to larŐe ǁholesalers (e͘Ő͘ CostCo) or
stores outside oston to buy items͘ TriƉs such as these
ǁould be imƉossible or ƉrohibiƟǀely edžƉensiǀe Ĩor a
carless household ǁithout access to a shared car͘
Concerns ǁith mobility are ƉarƟcularly ƉerƟnent in
Ɖarts oĨ oston ǁhere access to Ɖublic transƉortaƟon
is Ɖoor͘ Zesidents in these areas haǀe Ĩeǁer mobility
choices relaƟǀe to other Ɖarts oĨ the city͘ Public
transƉortaƟon in oston is comƉrised oĨ the buses (e͘Ő͘
^ilǀer >ine)͕ streetcars (e͘Ő͘ 'reen >ine)͕ and subǁays
(e͘Ő͘ Zed >ine) run by the MT or the ͞T͘͟
&iŐure 2 shoǁs mobility scores1ϵ Ĩor areas around
oston͘ The scores ǁere calculated usinŐ data Ĩrom the
MT and the Őrid ĨrameǁorŬ Ĩrom Mass'/^͘20 They
serǀe to aƉƉrodžimate access to Ɖublic transƉort Ĩor
a Őiǀen 250mdž250m cell as a ĨuncƟon oĨ its (straiŐhtͲ
line) distance Ĩrom MT staƟons and bus stoƉs͘ The
serǀice ĨreƋuency oĨ those staƟons and stoƉs is also
taŬen into account by the scorinŐ ĨuncƟon͘ ,iŐher
mobility scores (reƉresented by deeƉer shades oĨ
blue in &iŐure 2) indicate an area has Őreater access to
Ɖublic transƉortaƟon in terms oĨ Ɖrodžimity and serǀice
ĨreƋuency͘ test Zodžbury͕ orchester͕ :amaica Plain͕
Zoslindale͕ ,yde ParŬ͕ Zodžbury͕ riŐhton͕ llston͕ ^outh
oston͕ Charlestoǁn and ast oston all contain areas
that haǀe mobility access that is beloǁ the city median
(i͘e͘ less than 4͘05 or the boƩom Įǀe deciles)͘
s such͕ the City oĨ oston should seeŬ imƉroǀe the
mobility access oĨ residents in these areas ǁhen
allocaƟnŐ Ɖublic ƉarŬinŐ sƉaces to shared cars͘
4eduEe 8ehiEle Miles 6ravelled and
Greenhouse Gas Emissions
/n 2011͕ oston set the Őoal oĨ reducinŐ cityǁide ','
emissions to 25й beloǁ 2005 leǀels by 2020 and ϴ0й
beloǁ 2005 leǀels by 2050͘ Thus Ĩar͕ cityǁide emissions
are 1ϳй beloǁ 2005 leǀels͕ ǁhile emissions Ĩrom
municiƉal oƉeraƟons haǀe droƉƉed by 25й͘21
/n 2013͕ 2ϲ͘ϵй oĨ cityǁide emissions ǁere Ĩrom
transƉortaƟon͘ The City oĨ oston has tarŐeted
a 1ϳй reducƟon (0͘3 million metric tons) in ','
emissions by 2020͘ To meet this Őoal͕ oston has
tarŐeted a sMT reducƟon oĨ 5͘5й beloǁ 2005 leǀels
as ǁell as imƉroǀed Ĩuel economy Ĩor ǀehicles in the
city͘ etǁeen 2005 and 2013͕ total sMTs in oston
remained relaƟǀely unchanŐed althouŐh sMTs Ɖer
caƉita reduced by 0͘5й͘22
llocaƟnŐ Ɖublic ƉarŬinŐ sƉaces to carͲsharinŐ is
ǁorthǁhile Ĩor oston iĨ it Ɖroduces a net reducƟon in
cityǁide sMTs and ',' emissions͘
+nErease 4evenue or Minimi\e
Losses) for the City of Boston
The Ɖublic ƉarŬinŐ Ɖermits that the City oĨ oston
creates Ĩor shared cars can be Ɖriced hiŐh enouŐh that
reǀenues edžceed the costs oĨ maintaininŐ a Ɖublic
ƉarŬinŐ sƉace͕ neƫnŐ the city a ƉroĮt͘ lternaƟǀely͕
the city could choose to subsidinje carͲsharinŐ by ƉricinŐ
the Ɖermits beloǁ cost͘ tith this aƉƉroach͕ the Őoal
ǁould be to miniminje losses͘
/t is diĸcult Ĩor the City oĨ oston to accurately Ɖrice
its onͲstreet Ɖublic ƉarŬinŐ sƉaces due to the absence
oĨ an inǀentory and a dedicated budŐet allocaƟon͘ The
cost oĨ an onͲstreet Ɖublic ƉarŬinŐ sƉace is calculated
by esƟmaƟnŐ its share oĨ inĨrastructure deƉreciaƟon
and maintenance budŐets as ǁell as enĨorcement costs
that the sƉaces account Ĩor and then summinŐ those
all uƉ͘ &or edžamƉle͕ the City oĨ oston allocated Ψ21͘3
million in its 2015 budŐet Ĩor roadǁay reconstrucƟon͘
To calculate one inƉut Ĩor the cost oĨ ƉarŬinŐ͕ the
Mayor͛s Kĸce esƟmated that 5й (or Ψ1͘1 million) oĨ
that the roadǁay reconstrucƟon budŐet ǁas used Ĩor
Ɖublic ƉarŬinŐ sƉaces͘
hsinŐ this method͕ an onͲstreet ƉarŬinŐ sƉace costs
the city aƉƉrodžimately Ψ3͕500 Ɖer year͘ Metered
ƉarŬinŐ sƉaces allocated Ĩor shared cars ǁill also haǀe
the addiƟonal cost oĨ ĨoreŐone reǀenue that amounts
to aƉƉrodžimately Ψ3͕ϵ00 Ɖer year (assuminŐ 100й
uƟlinjaƟon at 10 hours a day͕ sidž days a ǁeeŬ͕ and 52
ǁeeŬs a year)͘ The City oĨ oston does Ŭnoǁ hoǁ
many ƉarŬinŐ sƉaces it has in municiƉal lots͘ /t also has
1ϵ DaƩheǁ Danish͕ ͞džƉloring dransiƚ and Driving ehavior in D͕
ǁiƚh 'oogle &usion dables͕͟ Ɖril 1ϵ͕ ϮϬ1ϰ͕ hƩƉs͗ͬͬsiƚes.google.coŵͬ
siƚeͬϯϳbillionŵilesͬ.
Ϯ1 Darƚy talsh͕ ͞'reenovaƚe osƚon ϮϬ1ϰ liŵaƚe cƟon Wlan hƉdaƚe͕͟
:anuary 15͕ ϮϬ15͕ hƩƉ͗ͬͬƉlan.greenovaƚebosƚon.orgͬ.
ϮϬ ^ee ƉƉendidž '͗ Deƚerŵining Dobiliƚy ^cores Ĩor calculaƟon ŵeƚhod
ϮϮ /bid.
12
B O S T O N M AY O R ’ S O F F I C E
Car-Sharing and Public Parking in Boston
FIGURE 2: MOBILITY SCORES
B O S T O N M AY O R ’ S O F F I C E
13
Car-Sharing and Public Parking in Boston
PAZ</E' SPACE dzPE
ESd/MAdE CKSd dK
d,E C/dz K& KSdKE
KnͲsƚreeƚ
Ψϯ͕5ϬϬ
Deƚered
Ψϯ͕5ϬϬ ;Ψϳ͕ϰϬϬ͕ ǁiƚh
Ĩoregone revenueͿ
Dunicipal loƚs
ΨϮ͕ϲϬϬ
PZ/sAdE PAZ</E'
SPACE PZ/CES
ZEYhESd &KZ
PZKPKSAL
ΨϮ͕ϰϬϬ Ͳ Ψϰ͕ϴϬϬ
Ψϯ͕5ϬϬ ;doǁnƚoǁnͿ or
ΨϮ͕ϳϬϬ ;elseǁhereͿ
TABLE 1: CITY OF BOSTON PARKING COST AND PRICE ESTIMATES (PER YEAR)
records oĨ its maintenance and uƉŐrade edžƉenditures
Ĩor the lots͘ ƉarŬinŐ sƉace in a municiƉal lot is
esƟmated to cost the city aƉƉrodžimately Ψ2͕ϲ00 Ɖer
year͘ These ĮŐures reƉresent the loǁest Ɖrices that the
City oĨ oston could charŐe C^Ks Ĩor ƉarŬinŐ sƉaces
and not lose money͘23
The hiŐhest Ɖrice that the City oĨ oston could charŐe
Ĩor any oĨ its Ɖublic ƉarŬinŐ sƉaces ǁould be the rental
rates oĨ a Ɖriǀate ƉarŬinŐ sƉace in the same area͘ /Ĩ the
Ɖrice oĨ a Ɖermit Ĩrom the city edžceeds the Ɖrice oĨ a
Ɖriǀate ƉarŬinŐ sƉace in a Őiǀen area͕ C^Ks are liŬely
to use the Ɖriǀate sƉace instead͘ ƋuicŬ checŬ on
CraiŐslist24 reǀeals that oīͲstreet Ɖriǀate ƉarŬinŐ sƉaces
in the acŬ ay area can Őo Ĩor uƉ to Ψ400 Ɖer month
(Ψ4͕ϴ00 Ɖer year)͘ Priǀate oīͲstreet sƉaces in ^outh
oston Őo Ĩor betǁeen Ψ200 and Ψ225 Ɖer month
(Ψ2͕400 to Ψ2͕ϳ00 Ɖer year)͘
/deally͕ there ǁould be more accurate inĨormaƟon on
the cost oĨ Ɖublic ƉarŬinŐ sƉaces to the City oĨ oston͘
This ǁould include analysis on the oƉƉortunity cost oĨ
usinŐ that sƉace Ĩor ǁider roads or͕ in the lonŐͲterm͕
realͲestate deǀeloƉment͘ ,oǁeǀer͕ that analysis is
beyond the scoƉe oĨ this reƉort͘ s such͕ this reƉort
assumes that the city͛s breaŬeǀen Ɖrice Ĩor a Ɖermit is
the releǀant cost in Table 1 and the hiŐhest Ɖrice it can
charŐe is the ŐoinŐ rate Ĩor a Ɖriǀate ƉarŬinŐ sƉace in a
Őiǀen area͘
Goal Priorities
The City oĨ oston did not edžƉlicitly ƉrioriƟnje the Őoals
discussed in this chaƉter͘ ,oǁeǀer͕ ƉrioriƟnjaƟon is
necessary Ĩor resolǀinŐ conŇicts betǁeen Őoals and
inĨorminŐ the recommendaƟons͘ To address this issue͕
this reƉort ƉrioriƟnjes the Őoals as Ĩolloǁs:
Table 1 summarinjes the Ɖreǀious discussion on Ɖrices
and also includes the Ɖrices that the City oĨ oston set
Ĩor shared car Ɖublic ƉarŬinŐ Ɖermits in its Z&P͘25
1͘ /ncrease residenƟal Ɖublic ƉarŬinŐ aǀailability
There are seǀeral edžƉlanaƟons Ĩor ǁhy the city͛s cost
esƟmates edžceed the loǁer bound rental Ɖrices Ĩor
a Ɖriǀate ƉarŬinŐ sƉace͘ The most straiŐhƞorǁard is
that the city͛s esƟmates are inŇated due the lacŬ oĨ an
inǀentory or dedicated budŐet Ĩor onͲstreet ƉarŬinŐ
sƉaces͘ more nuanced edžƉlanaƟon may inǀolǀe a
sƉaƟal dimension ǁhere the Ɖrice oĨ Ɖriǀate ƉarŬinŐ
sƉace is correlated ǁith real estate Ɖrices in an area͕
a Ĩactor that the city͛s maintenance costs are not
sensiƟǀe to͘
3͘ Zeduce sehicle Miles Traǀelled (sMT) and
'reenhouse 'as (',') emissions
Ϯϯ leanor :oseƉh͕ Cost of WarŬing ;Dayor͛s Kĸce͕ iƚy oĨ osƚon͕ &ebruary
ϮϬ͕ ϮϬ15Ϳ.
Ϯϰ raiglisƚ х osƚon х Warking Θ ^ƚorage͗ hƩƉ͗ͬͬbosƚon.craigslisƚ.orgͬsearchͬ
prk
2͘ /mƉroǀe mobility access Ĩor the carless
4͘ Madžiminje reǀenue (or miniminje losses)
This ƉrioriƟnjaƟon ǁas deriǀed usinŐ the ĨolloǁinŐ
consideraƟons:
» thether the Őoal ǁas edžƉlicitly stated in the City
oĨ oston͛s Z&P
» The conĮdence in the emƉirical eǀidence on the
aƩainability oĨ the Őoal (see nedžt chaƉter)
» The deŐree to ǁhich a Őiǀen Őoal conŇicts ǁith
other Őoals (see nedžt chaƉter)
Ϯ5 osƚon dransporƚaƟon Deparƚŵenƚ͕ ͞Driveosƚon͗ ZeƋuesƚ Ĩor Wroposals
Ĩor a osƚon sehicle ^haring Wrograŵ.͟
14
B O S T O N M AY O R ’ S O F F I C E
Car-Sharing and Public Parking in Boston
Chapter 3:
Impacts of Car-Sharing
T
, PZs/Kh^ C,PTZ enumerated the City
oĨ oston͛s Őoals Ĩor allocaƟnŐ Ɖublic ƉarŬinŐ
sƉaces to carͲsharinŐ orŐaninjaƟons (C^Ks):
increasinŐ residenƟal Ɖublic ƉarŬinŐ aǀailability͕
increasinŐ mobility access Ĩor the carless͕ reducinŐ
cityǁide ǀehicle miles traǀelled (sMT) and Őreenhouse
Őas (',') emissions͕ and increasinŐ reǀenues or
miniminjinŐ losses͘ CriƟcally͕ allocaƟnŐ Ɖublic ƉarŬinŐ
sƉaces to shared cars leaǀes residents ǁith Ĩeǁer
Ɖlaces to ƉarŬ͘ This tradeoī is only ǁorthǁhile iĨ these
Őoals can be achieǀed͘
To determine ǁhether the Őoals are aƩainable͕ this
chaƉter edžamines the imƉacts oĨ carͲsharinŐ͘ This
eīort is comƉlicated by the larŐely indirect relaƟonshiƉ
betǁeen those Őoals and the Ɖolicy Ĩor allocaƟnŐ Ɖublic
ƉarŬinŐ sƉaces to shared cars͘ &iŐure 3 illustrates the
comƉledž causal relaƟonshiƉs inǀolǀed͘
The City oĨ oston has tǁo main leǀers ǁhen
imƉlemenƟnŐ its allocaƟon Ɖolicy: the numďer oĨ
Ɖuďlic ƉarŬinŐ sƉaces it allocates to shared cars and
the Ɖrice it charŐes CSKs Ĩor those sƉaces͘2ϲ The causal
chain betǁeen the City oĨ oston͛s allocaƟon Ɖolicy
Ϯϲ s ƚhe ŵagniƚude oĨ ƚhe iŵpacƚs is sensiƟve ƚhe prodžiŵiƚy ƚo a shared car͕
ƚhe locaƟon oĨ allocaƚed public parking spaces could be considered a ƚhird
lever. &or ƚhe sake oĨ breviƚy and siŵpliciƚy͕ locaƟon has been oŵiƩed Ĩroŵ
ƚhis discussion buƚ is edžplored Ĩurƚher in hapƚer ϰ.
B O S T O N M AY O R ’ S O F F I C E
and its Őoals can be Ĩound by starƟnŐ Ĩrom the city͛s
Ɖolicy leǀers ;in ďlueͿ and ĨolloǁinŐ the arroǁs to a
Őiǀen Őoal ;in ƉinŬͿ͘
ThouŐh the causal looƉ diaŐram in &iŐure 3 is a
ƉoǁerĨul tool͕ it is also Ĩairly comƉledž͘ /n liŐht oĨ this͕ it
is a useĨul edžercise to ǁorŬ throuŐh the diaŐram ǁith
an edžamƉle͘ Consider the imƉact on WuďůiĐ WarŬing
ǀaiůaďiůitLJ iĨ the City oĨ oston edžoŐenously increases
the number oĨ WuďůiĐ WarŬing SƉaĐĞs for SharĞĚ Cars
ǁhile holdinŐ the SharĞĚ Car WarŬing WĞrŵit WriĐĞ
constant:
1͘ tith more Ɖublic ƉarŬinŐ sƉaces allocated
to shared cars͕ C^Ks Ɖlace more shared cars
in oston͘ The causal relaƟonshiƉ is denoted
by the Őreen directed line betǁeen the tǁo
ǀariables (WuďůiĐ WarŬing SƉaĐĞs for SharĞĚ Cars
and SharĞĚ CarsͿ terminaƟnŐ ǁith an arroǁhead
and a Ɖlus siŐn (н)͘ This indicates that the tǁo
ǀariables are ƉosiƟǀely correlated: holdinŐ all
else eƋual͕ a chanŐe in the number oĨ WuďůiĐ
WarŬing SƉaĐĞs for SharĞĚ Cars ǁill cause a
chanŐe in the same direcƟon ǁith the number
oĨ Shared Cars͘
2͘ s the number oĨ Shared Cars increases, they
become a ǀiable subsƟtute Ĩor residents͛ oǁn
15
Car-Sharing and Public Parking in Boston
FIGURE 3: POTENTIAL IMPACTS OF ALLOCATING PUBLIC PARKING TO SHARED CARS
cars, causinŐ a decrease in the number oĨ Wriǀate
sehiĐůes in oston͘ This neŐaƟǀe correlaƟon
betǁeen Shared Cars and Wriǀate sehiĐůes is
denoted by the red directed line betǁeen tǁo
ǀariables terminaƟnŐ ǁith an arroǁhead and
a minus siŐn (Ͳ)͘ ,oǁeǀer, this imƉact does
not taŬe Ɖlace oǀer a Ɖeriod oĨ days, ǁeeŬs, or
months, but rather years͘ The delayed eīect is
reƉresented by ƉuƫnŐ a bar (ͮ) on the directed
line betǁeen the tǁo ǀariables͘
3͘ &urthermore, an increase in the number oĨ
Shared Cars imƉroǀes the DoďiůitLJ ĐĐess for the
Carless in oston, as they noǁ haǀe access to an
addiƟonal mobility oƉƟon͘
4͘ /mƉroǀed DoďilitLJ ĐĐess for the Carless reduces
the need Ĩor them to Ɖurchase their oǁn Wriǀate
sehiĐles͘ ThouŐh this doesn͛t remoǀe any Wriǀate
sehiĐles Ĩrom oston, it Ɖreǀents neǁ ones Ĩrom
16
beinŐ added, hence the neŐaƟǀe correlaƟon͘
5͘ s the number oĨ Wriǀate sehiĐles decreases,
residents do not need as many onͲstreet ƉarŬinŐ
sƉaces Ĩor their cars, reducinŐ WuďliĐ WarŬing
eŵand͘ This is another edžamƉle oĨ a ƉosiƟǀe
relaƟonshiƉ ʹ a decrease in one ǀariable causes
a decrease in another ǀariable͘
ϲ͘ tith loǁer demand, WuďliĐ WarŬing ǀailaďilitLJ
increases, achieǀinŐ one oĨ the Őoals set by the
City oĨ oston (oǀer the lonŐͲterm)͘
ϳ͘ &urthermore, increasinŐ WuďliĐ WarŬing
ǀailaďilitLJ is liŬely to miƟŐate Ɖublic oƉƉosiƟon
to allocaƟnŐ Ɖublic ƉarŬinŐ sƉaces to shared
cars͘ This alloǁs the City oĨ oston to Ĩurther
increase the number oĨ WuďliĐ WarŬing SƉaĐes
for Shared Cars͘ EoƟce that the causal chain
starƟnŐ ǁith WuďliĐ WarŬing SƉaĐes for Shared
B O S T O N M AY O R ’ S O F F I C E
Car-Sharing and Public Parking in Boston
Cars has noǁ ended on itselĨ, indicaƟnŐ it is Ɖart
oĨ a ĨeedbacŬ looƉ͘ /Ĩ a ĨeedbacŬ looƉ maŐniĮes
(once traǀersed bacŬ to its starƟnŐ Ɖoint) an
edžoŐenous chanŐe to a ǀariable, it is a ƉosiƟǀe
(or reinĨorcinŐ) ĨeedbacŬ looƉ͘ This ƉarƟcular
reinĨorcinŐ looƉ is named ͞The ^noǁball īect͟
ǁith an ͞Z͟ surrounded by a clocŬǁise arroǁ
denoƟnŐ the direcƟon oĨ the looƉ͘
ϴ͘ ^tarƟnŐ aŐain and moǀinŐ in a diīerent
direcƟon, increasinŐ the WuďliĐ WarŬing SƉaĐes
for Shared Cars also reduces WuďliĐ WarŬing
SuƉƉlLJ because Ĩeǁer sƉaces are aǀailable to
residents Ĩor ƉarŬinŐ͘
ϵ͘ ecreasinŐ the WuďliĐ WarŬing SuƉƉlLJ also
decreases WuďliĐ WarŬing ǀailaďilitLJ͘
10͘ This results in oƉƉosiƟon Ĩrom residents, ǁho
are liŬely to aƉƉly Ɖressure to reduce the
number oĨ WuďliĐ WarŬing SƉaĐes for Shared Cars͘
The last three ǀariables are connected in such
a ǁay that another ĨeedbacŬ looƉ (indicated
ǁith a ͞1͟ and the label ͞KƉƉosiƟon͟) is
Ĩormed͘ The KƉƉosiƟon looƉ is a neŐaƟǀe (or
balancinŐ) ĨeedbacŬ looƉ because it counteracts
(once traǀersed bacŬ to its starƟnŐ Ɖoint) the
edžoŐenous chanŐe to WuďliĐ WarŬing SƉaĐes for
Shared Cars͘
/t is imƉortant to note that the model in the causal
looƉ diaŐram only describes the ƉotenƟal imƉacts oĨ
allocaƟnŐ Ɖublic ƉarŬinŐ sƉaces to shared cars͘ The
remainder oĨ this chaƉter deǀeloƉs these ƉotenƟal
imƉacts Ĩurther and edžƉlores ǁhether they are
suƉƉorted by emƉirical eǀidence Ĩrom the literature on
carͲsharinŐ͘
Evaluating the EmRiriEal 4esearEh on
Car-sharing
^ubstanƟal research has been done by C^Ks and
indeƉendent transƉort researchers on the imƉacts oĨ
carͲsharinŐ, ƉarƟcularly ǀehicle sheddinŐ and chanŐes
in traǀel behaǀior͘2ϳ This reƉort only considers research
Ĩrom indeƉendent transƉort researchers since it
assumes that C^Ks haǀe a ǀested interest in oǀerstaƟnŐ
the ƉosiƟǀe imƉacts͘ &or edžamƉle, iƉcar͛s ǁebsite
claims ͞each and eǀery iƉcar taŬes 15 ƉersonallyͲ
Ϯϳ DillardͲall͕ dCZW ZeƉort ϭϬϴ͗ Car-Sharing͗ there and ,oǁ /t SuĐĐeeds.
B O S T O N M AY O R ’ S O F F I C E
oǁned ǀehicles oī the road͘͟2ϴ This ĮŐure is hiŐher
than the most oƉƟmisƟc esƟmates in the indeƉendent
studies that this reƉort dreǁ its conclusions Ĩrom͘
hnĨortunately, eǀen Ĩor the indeƉendent research,
there are three concerns:
/nternal salidity
The Įrst concern is methodoloŐical issues ǁith the
research that diminishes the credibility oĨ their
conclusions around the imƉacts oĨ carͲsharinŐ͘
Much oĨ the emƉirical research relies on surǀeyinŐ
members about their behaǀior beĨore and aŌer they
ũoined a C^K͘ &or edžamƉle, members ǁere asŬed hoǁ
many ǀehicles they oǁned beĨore and aŌer they ũoined
a C^K͘2ϵ 30 The diīerence betǁeen the tǁo ǀalues is
idenƟĮed as the causal eīect oĨ carͲsharinŐ͘ ,oǁeǀer,
this aƉƉroach iŐnores the Ɖossibility that members may
haǀe ŐoƩen rid oĨ those ǀehicles eǀen iĨ they hadn͛t
ũoined a C^K͘ /n liŐht oĨ this, there is a stronŐ Ɖossibility
that many oĨ the imƉacts are oǀerstated͘
&urther, most studies do not emƉloy a control ŐrouƉ,
ǁhich renders ƉroblemaƟc the conclusions draǁn
about ǁhat members ǁould haǀe done iĨ they had
not ũoined a C^K͘ &or edžamƉle, some studies try to
determine iĨ C^K membershiƉ Ɖreǀents net increases
in ǀehicle oǁnershiƉ͘ ZesƉondents ǁere asŬed ǁhether
they aǀoided ƉurchasinŐ ǀehicles since ũoininŐ a C^K͘
'iǀen the sƉeculaƟǀe nature oĨ the ansǁers, it is liŬely
that these numbers are oǀerstated as ǁell͘
This ƉotenƟal misaƩribuƟon and oǀerstatement oĨ
ƉosiƟǀe imƉacts (e͘Ő͘ reducƟons in ǀehicle oǁnershiƉ
and sMT) to carͲsharinŐ reƉresents the Ɖrimary threat
to inĨormed Ɖolicy decision maŬinŐ: consƟtuents
ƉotenƟally lose a Ɖublic ƉarŬinŐ sƉace ǁithout the
comƉensaƟnŐ beneĮt oĨ increasinŐ Ɖublic ƉarŬinŐ
aǀailability or reducinŐ sMT͘ To miƟŐate these
Ɖroblems, this reƉort adoƉts tǁo aƉƉroaches ǁhen
edžamininŐ the literature͘
&irst, this reƉort ranŬed research accordinŐ to Ĩactors
Ϯϴ ipcar͗ /s ipcar Ĩor ŵe͍ hƩp͗ͬͬǁǁǁ.njipcar.coŵͬisͲiƚηgreenbeneĮƚs
Ϯϵ layƚon >ane͕ ͞Whillyar^hare͗ &irsƚͲzear ^ocial and Dobiliƚy /ŵpacƚs oĨ
arsharing in Whiladelphia͕ Wennsylvania͕͟ dransƉortaƟon ZesearĐh ZeĐord͗
:ournal of the dransƉortaƟon ZesearĐh Board 1ϵϮϳ ;:anuary 1͕ ϮϬϬ5Ϳ͗
15ϴʹϲϲ.
ϯϬ Zichard Kaƚnjev͕ ͞ar ^haring͗ Neǁ pproach ƚo hrban dransporƚaƟon
Wrobleŵs͕͟ nalLJses of SoĐial /ssues and WuďliĐ WoliĐLJ ϯ͕ no. 1 ;Deceŵber 1͕
ϮϬϬϯͿ͗ ϲ5ʹϴϲ.
17
Car-Sharing and Public Parking in Boston
FIGURE 4: IMPACTS ON PRIVATE VEHICLE OWNERSHIP AND PUBLIC PARKING AVAILABILITY
such as the methodoloŐy and samƉle sinje (see
ƉƉendidž : ^tudies on /mƉacts oĨ CarͲ^harinŐ)͘ /t then
only dreǁ conclusions Ĩrom hiŐh Ƌuality research (see
ƉƉendidž : etailed Zeǀieǁ oĨ ^hortlisted ^tudies
on /mƉacts oĨ CarͲsharinŐ)͘ &our studies made the
Įnal cut͘ The Įrst is a larŐeͲscale surǀey carͲsharinŐ
in Eorth merica conducted in 200ϵ by lliot MarƟn,
^usan ^haheen, and :eīrey >idicŬer͘31 The remaininŐ
three studies ǁere conducted on ^an &rancisco͛s City
Car^hare by Zobert Cerǀero and ǀarious other authors
betǁeen 2001 and 2005͘32 33 34
ϯ1 llioƚ DarƟn͕ ^usan ^haheen͕ and :eīrey >idicker͕ ͞/ŵpacƚ oĨ arsharing
on ,ousehold sehicle ,oldings͗ Zesulƚs Ĩroŵ a Norƚh ŵerican ^haredͲhse
sehicle ^urvey.͟
ϯϮ Zoberƚ ervero͕ ͞iƚy ar^hare͗ &irsƚͲzear dravel Deŵand /ŵpacƚs͕͟
dransƉortaƟon ZesearĐh ZeĐord͗ :ournal of the dransƉortaƟon ZesearĐh
Board 1ϴϯϵ͕ no. 1 ;ϮϬϬϯͿ.
ϯϯ Zoberƚ ervero and zuhsin dsai͕ ͞iƚy ar^hare in ^an &rancisco͕ aliĨornia͗
^econdͲzear dravel Deŵand and ar Kǁnership /ŵpacƚs͕͟ dransƉortaƟon
ZesearĐh ZeĐord͗ :ournal of the dransƉortaƟon ZesearĐh Board 1ϴϴϳ
;:anuary 1͕ ϮϬϬϰͿ.
ϯϰ Zoberƚ ervero͕ aron 'olub͕ and rendan Nee͕ ͞iƚy ar^hare͗ >ongerͲ
derŵ dravel Deŵand and ar Kǁnership /ŵpacƚs͕͟ dransƉortaƟon ZesearĐh
18
^econd, this reƉort uses the loǁerͲbound oĨ Ɖroũected
ǀalues Ĩrom the studies͘ The Ɖolicy danŐer oĨ
understaƟnŐ the ƉosiƟǀe imƉacts oĨ carͲsharinŐ is less
than oǀerstaƟnŐ them͘
džternal ǀalidity
nother concern is ǁhether the results oĨ these studies
can be aƉƉlied to other contedžts (i͘e͘ edžternal ǀalidity)͘
Conclusions draǁn in other ciƟes Ĩrom a diīerent Ɵme
may not be aƉƉlicable to oston ǁhich has its oǁn
set oĨ temƉoral, ŐeoŐraƉhical, economic, and cultural
characterisƟcs͘
Policy Zeleǀance
The Įnal concern is that the research on carͲsharinŐ
edžclusiǀely edžamines behaǀioral chanŐes oĨ C^K
members, not the actual imƉact oĨ these chanŐes on
the communiƟes they liǀe in͘ Thus, the conclusions
ZeĐord͗ :ournal of the dransƉortaƟon ZesearĐh Board 1ϵϵϮ ;:anuary 1͕
ϮϬϬϳͿ.
B O S T O N M AY O R ’ S O F F I C E
Car-Sharing and Public Parking in Boston
FIGURE 5: IMPACTS ON MOBILITY ACCESS
oĨ the research may haǀe liƩle siŐniĮcance Ĩor a
ƉolicymaŬer, eǀen iĨ they are staƟsƟcally siŐniĮcant
amonŐ C^K members͘ &or edžamƉle, iĨ a Ƌuarter
oĨ C^K members Őiǀe uƉ their cars, but they only
reƉresent a small ĨracƟon oĨ a city͛s ƉoƉulaƟon, the
imƉroǀement in ƉarŬinŐ aǀailability is ŐoinŐ to be ǀery
modest͘ ThereĨore, the deŐree oĨ imƉact in oston is
deƉendent on the ƉroƉorƟon oĨ ostonians that are
C^K members͘
Private 8ehiEle 1YnershiR
thile most oĨ the imƉacts oĨ carͲsharinŐ studied in
the aǀailable literature are idenƟcal to city͛s Őoals
(e͘Ő͘ sMT and ','), some Őoals (such as increasinŐ
residenƟal ƉarŬinŐ aǀailability) ǁere not studied
directly͘ &or such situaƟons this reƉort ǁorŬs its ǁay
bacŬǁards alonŐ the causal chain Ĩrom the Őoal oĨ
interest to a relaƟonshiƉ that has been studied͘
/n the case oĨ increasinŐ ƉarŬinŐ aǀailability, the
releǀant relaƟonshiƉ is betǁeen number oĨ shared cars
and chanŐes in Ɖriǀate ǀehicle oǁnershiƉ͘ /ntuiƟǀely,
reducinŐ Ɖriǀate ǀehicle oǁnershiƉ reduces the
demand Ĩor ƉarŬinŐ sƉaces (both Ɖublic and Ɖriǀate),
thus increasinŐ Ɖublic ƉarŬinŐ aǀailability͘
&iŐure 4 shoǁs the relaƟonshiƉs that are releǀant to
chanŐinŐ Ɖriǀate ǀehicle oǁnershiƉ͘ /t also illustrates
hoǁ the reducƟon in ǀehicle oǁnershiƉ occurs in tǁo
Ĩorms:
» Priǀate sehicle ^heddinŐ ʹ members sell a
ǀehicle they oǁn͘
» &oreŐone Priǀate sehicle Purchases ʹ members
ǁho do not oǁn cars choose to ĨoreŐo or
ƉostƉone indeĮnitely the Ɖurchase oĨ a ǀehicle͘
B O S T O N M AY O R ’ S O F F I C E
The introductory secƟon oĨ this chaƉter already
edžƉlained most oĨ the ƉotenƟal imƉacts Ĩrom
increasinŐ the number oĨ Ɖublic ƉarŬinŐ sƉaces
allocated to shared cars͘ side Ĩrom those imƉacts,
there is also ƉotenƟal Zebound eīect caused by a
neŐaƟǀe ĨeedbacŬ looƉ (͞2͟) betǁeen Priǀate sehicles
and Public ParŬinŐ ^hortaŐe͘ Kǀer the lonŐͲterm, as
the Ɖublic ƉarŬinŐ shortaŐe abates, Ɖriǀate ǀehicle
oǁnershiƉ becomes more aƩracƟǀe because ĮndinŐ
ƉarŬinŐ sƉaces becomes easier͘ TheoreƟcally, residents
Ɖurchase more ǀehicles oīseƫnŐ some oĨ the earlier
reducƟons͘ ,oǁeǀer, there is liƩle documented
eǀidence oĨ this unintended conseƋuence and this
reƉort assumes it occurs on too modest a scale to haǀe
a maũor imƉact͘
mƉirical ǀidence
monŐ the shortlisted studies, esƟmates on the
number oĨ ǀehicles shed are relaƟǀely consistent and
ǁithin in a narroǁ bound͘ /n their larŐeͲscale surǀey
oĨ carͲsharinŐ in Eorth merica, MarƟn et al͘ esƟmate
that each shared car taŬes Ĩour to sidž ǀehicles oī the
road͘35 Cerǀero and Tsai esƟmate that in the tǁo years
aŌer City Car^hare͛s launch in 2001, each oĨ its shared
cars tooŬ sidž ǀehicles oī the road͘ then usinŐ ǀehicle
Ɖurchases Ĩor nonͲmember households (i͘e͘ the control
ŐrouƉ), the same study esƟmates that each shared car
also Ɖreǀented the Ɖurchase oĨ one car͘3ϲ
/n the last oĨ their City Car^hare studies, Cerǀero and
Tsai Ɖroǀide a ƉredicƟǀe ordinal loŐit model͘3ϳ In this
model, C^K membershiƉ increases the liŬelihood oĨ
ϯ5 DarƟn͕ ^haheen͕ and >idicker͕ ͞/ŵpacƚ oĨ arsharing on ,ousehold
sehicle ,oldings͗ Zesulƚs Ĩroŵ a Norƚh ŵerican ^haredͲhse sehicle ^urvey.͟
ϯϲ ervero and dsai͕ ͞iƚy ar^hare in ^an &rancisco͕ aliĨornia.͟
ϯϳ ervero͕ 'olub͕ and Nee͕ ͞iƚy ar^hare.͟
19
Car-Sharing and Public Parking in Boston
FIGURE 6: IMPACTS ON VMT AND GHG EMISSIONS
sheddinŐ one or more ǀehicles by aƉƉrodžimately 11
ƉercentaŐe Ɖoints͘3ϴ
CombininŐ this eǀidence, this reƉort esƟmates
that each shared car induces the sheddinŐ oĨ Ĩour
ǀehicles and Ɖreǀents the Ɖurchase oĨ one more͘ This
reƉresents a net reducƟon oĨ Ĩour ǀehicles Ɖer shared
car (the shared car reƉresents a one ǀehicle increase)͘
Mobility AEEess
KĨ all the imƉacts discussed in this chaƉter, the
imƉact on the mobility access oĨ oston residents oĨ
allocaƟnŐ Ɖublic ƉarŬinŐ sƉaces to shared cars is the
most straiŐhƞorǁard͘ Mobility access is imƉroǀed
because an increase in Ɖublic ƉarŬinŐ sƉaces Ĩor shared
cars results in addiƟonal shared cars, creaƟnŐ ǁider
ŐeoŐraƉhical coǀeraŐe and Őreater aǀailability͘
mƉirical ǀidence
In their third study on ^an &rancisco͛s City Car^hare,
Cerǀero et al Ĩound that, iĨ a shared car ǁas not
aǀailable, surǀeyed members ǁould haǀe most
liŬely not made 30й oĨ their triƉs͘ Eearly 40й oĨ
those addiƟonal triƉs ǁere Ĩor shoƉƉinŐ͘ The neǁly
accessible triƉs reƉresent a 43й imƉroǀement3ϵ in
ϯϴ ^ee ppendidž &͗ WredicƟve Dodel on hanges in sehicle Kǁnership Ĩor
iƚy ar^hare Ĩor calculaƟon ŵeƚhod
ϯϵ ervero eƚ al Ĩound ƚhaƚ ϯ ouƚ 1Ϭ ƚrips ŵade in a shared car ǁould have
20
mobility Ĩor City Car^hare members͘40
nother surǀey oĨ carͲsharinŐ members in 2005 Ĩound
that oǀer 5ϴй oĨ resƉondents Ĩelt that they could
access more desƟnaƟons since ũoininŐ a C^K͘41
lthouŐh it is unable to esƟmate an edžact maŐnitude,
this reƉort concludes that carͲsharinŐ does imƉroǀe
mobility access͘
8ehiEle Miles 6ravelled 8M6) and
Greenhouse Gas G*G) Emissions
thile the relaƟonshiƉ betǁeen sMT and ','
emissions is straiŐhƞorǁard, the relaƟonshiƉ betǁeen
carͲsharinŐ and sMT is more comƉledž͘ This is illustrated
by the number oĨ causal chains that end in sehicle
Miles Traǀelled in &iŐure ϲ͘
C^K members reduce their sMT by sellinŐ the cars that
they oǁn, iĨ any͘42 Most oĨ the costs associated ǁith
ǀehicle oǁnershiƉ are Įdžed costs (e͘Ő͘ deƉreciaƟon,
insurance, ƉarŬinŐ sƉace rental, license, reŐistraƟon,
tadžes)͘ Knce Ɖaid, these are reŐarded as sunŬ costs͘
This results in the marŐinal cost (Ɖer triƉ or distance
oƚherǁise noƚ been ŵade. dhus͕ ƚhe iŵproveŵenƚ is ;1ϬͲϳͿ ͬ ϳ Ύ 1ϬϬй с
ϰϮ.ϴϲй
ϰϬ ervero͕ 'olub͕ and Nee͕ ͞iƚy ar^hare.͟
ϰ1 DillardͲall͕ dCZW ZeƉort ϭϬϴ͗ Car-Sharing͗ there and ,oǁ /t SuĐĐeeds.
ϰϮ /bid.
B O S T O N M AY O R ’ S O F F I C E
Car-Sharing and Public Parking in Boston
FIGURE 7: IMPACT OF PERMIT PRICES
traǀelled) Ĩor a Ɖriǀate ǀehicle beinŐ ǀery small relaƟǀe
to its aǀeraŐe cost͘ then a shared car is used as a
subsƟtute Ĩor a Ɖriǀate ǀehicle, the marŐinal costs
are much closer to the aǀeraŐe cost͘ ThereĨore,
ǁhat results is more ũudicious use oĨ the shared car
relaƟǀe to other modes (ǁalŬinŐ, biŬinŐ, and Ɖublic
transƉort)͘43
&inally, besides reducƟons in sMT, ',' emission
reducƟons are also Ɵed to the Ňeet comƉosiƟon oĨ
the C^K and member households͘ ^ince they oŌen
bear Ĩuel costs, C^Ks tend to use Ĩuel eĸcient ǀehicles
ǁith loǁer carbon ĨootƉrints͘ then sheddinŐ ǀehicles,
members may also be ŐiǀinŐ uƉ older ǀehicles that are
more ƉolluƟnŐ͘45
&urthermore, alleǀiaƟnŐ the Ɖublic ƉarŬinŐ shortaŐe
ƉotenƟally reduces sMT (and ',' emissions) because
residents sƉend less Ɵme cruisinŐ in search oĨ a ƉarŬinŐ
sƉace͘
ConseƋuently, the ƉotenƟal net chanŐes in sMT and
',' emissions are conƟnŐent uƉon ǁhich oĨ the
aĨoremenƟoned causal chains are dominant͘
,oǁeǀer, these reducƟons in sMT could be oīset by
shared car usaŐe by carless indiǀiduals͘ In the status
Ƌuo, these indiǀiduals do not contribute to oston͛s
sMT and ',' emission totals͘ llocaƟnŐ Ɖublic ƉarŬinŐ
sƉaces to shared cars ǁill increase the number oĨ
shared cars in oston and the access oĨ the carless to
automobiles͘ TriƉs that ǁere Ɖreǀiously ĨoreŐone or
made on other modes ǁill be made ǁith a shared car,
resulƟnŐ in a sMT increase͘ This reƉresents a conŇict
betǁeen the Őoals oĨ increasinŐ mobility access Ĩor the
carless and reducinŐ sMT͘
In addiƟon, it is also Ɖossible that reducinŐ ƉarŬinŐ
demand miŐht encouraŐe an increase in sMT as the
Ɖroblem ǁith ĮndinŐ a ƉarŬinŐ sƉace abates in oston͘
There is anecdotal eǀidence that ƉeoƉle choose to cut
doǁn on triƉs in their oǁn cars because they ͞lose͟
their sƉace and haǀe the diĸculty in ĮndinŐ ƉarŬinŐ
sƉaces ǁhen they return͘44
mƉirical ǀidence
In all three studies on the imƉacts oĨ ^an &rancisco͛s
City Carshare, Cerǀero et al Ĩound no staƟsƟcally
siŐniĮcant diīerence in aǀeraŐe sMT betǁeen
members and nonͲmembers͘ 4ϲ 4ϳ 4ϴ ,oǁeǀer, there
ǁere tǁo results that ǁere staƟsƟcally siŐniĮcant in
the third study͘ &irst, members had 1͘ϴϳ Ĩeǁer modeͲ
adũusted ǀehicle miles traǀelled (MsMT) than nonͲ
members͘ MsMT are calculated by diǀidinŐ sMT by
the number oĨ occuƉants in the ǀehicle Ĩor a Őiǀen
triƉ͘ This same study also Ĩound that ǁhen usinŐ a
reŐression model ǁhich controlled Ĩor Ĩactors such as
aŐe, income, and ǀehicle oǁnershiƉ, beinŐ a member
oĨ City Car^hare reduced daily traǀel by aƉƉrodžimately
ϳ miles͘4ϵ
In edžamininŐ ',' emissions, a study by MarƟn et al
Ĩound that ǁhile carless households increased their
ϰ5 DillardͲall͕ dCZW ZeƉort ϭϬϴ͗ Car-Sharing͗ there and ,oǁ /t SuĐĐeeds.
ϰϲ ervero͕ ͞iƚy ar^hare͗ &irsƚͲzear dravel Deŵand /ŵpacƚs.͟
ϰϯ Karl ^ƚeininger͕ aroline sogl͕ and Zalph eƩl͕ ͞arͲ^haring KrganinjaƟons͗
dhe ^inje oĨ ƚhe Darkeƚ ^egŵenƚ and Zevealed hange in Dobiliƚy ehavior͕͟
dransƉort WoliĐLJ ϯ͕ no. ϰ ;Kcƚober 1ϵϵϲͿ͗ 1ϳϳʹϴ5.
ϰϰ tallack͕ ͞osƚon soǁs ƚo džaŵine Warking Zules Ĩor Zesidenƚs.͟
B O S T O N M AY O R ’ S O F F I C E
ϰϳ ervero and dsai͕ ͞iƚy ar^hare in ^an &rancisco͕ aliĨornia͕͟ Ͳ.
ϰϴ ervero͕ 'olub͕ and Nee͕ ͞iƚy ar^hare.͟
ϰϵ /bid.
21
Car-Sharing and Public Parking in Boston
sMT, there ǁas oǀerall net reducƟon in sMT amonŐ
C^K members͘ This translated into an aǀeraŐe net
reducƟon oĨ 0͘5ϴ metric tons oĨ ',' Ɖer year (t ','ͬ
year) Ĩor households that ũoined C^Ks͘ The study Őoes
on to esƟmate that ĨoreŐone triƉs, due to ǀehicle
sheddinŐ, Ĩurther reduced emissions by 0͘2ϲ t ','ͬ
year brinŐinŐ the ͞Ĩull͟ reducƟon to 0͘ϴ4 t ','ͬyear͘
oth oĨ these esƟmates ǁere staƟsƟcally siŐniĮcant͘50
This reƉort adoƉts the loǁer bound esƟmates Ĩor each
study and esƟmates that shared car usaŐe ;throuŐh
CSK memďershiƉͿ results in households reducinŐ their
aǀeraŐe daily MsMd ďy 1͘ϴϳ miles and their ','
emissions ďy 0͘5ϴ metric tons Ɖer year͘
4evenue and the Shared Car ParMing
Permit PriEe
Thus Ĩar, this chaƉter has discussed the imƉact oĨ
allocaƟnŐ more Ɖublic ƉarŬinŐ sƉaces to shared cars
ǁhile holdinŐ the Ɖermit Ɖrice constant͘ The neŐaƟǀe
relaƟonshiƉ betǁeen the Ɖermit Ɖrice and the number
oĨ shared cars in oston is shoǁn in &iŐure ϳ: iĨ the
Ɖrice oĨ the Ɖermits Őoes uƉ, there ǁill be Ĩeǁer shared
cars in oston͘ More Ɖrecisely, C^Ks ǁill Ɖlace Ĩeǁer
cars in oston iĨ the Ɖrice is aboǀe their ǁillinŐness to
Ɖay Ĩor a Őiǀen ƋuanƟty oĨ Ɖublic ƉarŬinŐ sƉaces͘ The
conǀerse is also true͘ Most imƉortant, this hiŐhliŐhts a
conŇict betǁeen raisinŐ reǀenue and all the other Őoals
that only accrue throuŐh more shared cars in oston͘
mƉirical ǀidence
There is ǀery liƩle research on the Ɖrice sensiƟǀity oĨ
C^Ks͘ ,oǁeǀer, the resƉonse to the Z&P Ɖroǀides some
insiŐht: C^Ks aƉƉlied Ĩor all ϴ0 edicated Permits and
150 &reeͲŇoaƟnŐ Permits͘51 This indicates that Ĩor these
ƋuanƟƟes oĨ Ɖublic ƉarŬinŐ sƉaces, the Ɖrice oĨ the
Ɖermits in the Z&P is at or beloǁ ǁhat the C^Ks ǁere
ǁillinŐ to Ɖay͘
» IncreasinŐ the City oĨ oston͛s reǀenues by
charŐinŐ a hiŐher Ɖrice Ĩor the shared car Ɖublic
ƉarŬinŐ Ɖermits is liŬely to limit the deŐree to
ǁhich other Őoals are achieǀed because C^Ks
ǁill Ɖlace Ĩeǁer shared cars in oston͘
» ImƉroǀinŐ access to mobility Ĩor the carless ǁill
ƉotenƟally run counter to the Őoal oĨ reducinŐ
sMT and ',' emissions͘
Eeǀertheless, the ƉrioriƟes Ĩor the Őoals set at the end
oĨ the Ɖreǀious chaƉter Ɖroǀide Őuidance on hoǁ to
resolǀe this:
» s madžiminjinŐ reǀenue has the loǁest Ɖriority
amonŐ all the city͛s Őoals, the Ɖrice oĨ a Ɖublic
ƉarŬinŐ Ɖermit should be set as loǁ as necessary
to achieǀe the city͛ other Őoals͘
» ImƉroǀinŐ access to mobility Ĩor the carless
should taŬe Ɖriority oǀer reducinŐ sMT and ','
emissions͘ ,oǁeǀer, there is some eǀidence that
the sMT increase oĨ a carless indiǀidual ǁho
uses a shared car is loǁer than it ǁould haǀe
been iĨ they had Ɖurchased their oǁn car͘52
eyond these conŇicts, there are tǁo main concerns
ǁith reŐard to the Ɖolicy releǀance oĨ the emƉirical
ĮndinŐs in this chaƉter to the City oĨ oston͘
&irst, as stated earlier, all studies Ĩocused edžclusiǀely
on the behaǀioral chanŐes oĨ C^K members͘ Thus the
maŐnitude oĨ the actual imƉacts on the City oĨ oston
is deƉendent on the number oĨ C^K members in the
city͘
5Ϭ .t. DarƟn and ^.. ^haheen͕ ͞'reenhouse 'as ŵission /ŵpacƚs oĨ
arsharing in Norƚh ŵerica͕͟ / dransaĐƟons on /ntelligent dransƉortaƟon
Systems 1Ϯ͕ no. ϰ ;Deceŵber ϮϬ11Ϳ͗ 1Ϭϳϰʹϴϲ.
^econd, all studies only edžamined the ͲtoͲ model oĨ
carͲsharinŐ͘ There has been liƩle emƉirical research
done on the imƉacts oĨ the ͲtoͲ model oĨ carͲ
sharinŐ͘ The added Ňedžibility and loǁer Ɖrice oĨ the
oneͲǁay triƉs on the ͲtoͲ model suŐŐest that it may
beƩer imƉroǀe accessibility and induce Őreater ǀehicle
sheddinŐ͘ ,oǁeǀer, these same Ĩactors may also
mean that there miŐht be net sMT and ',' emission
increases͘ sMT and ',' emissions may be Ĩurther
increased iĨ rebalancinŐ is reƋuired͘ ZebalancinŐ is the
transĨer oĨ shared cars Ĩrom one locaƟon to another
in order to ensure suĸcient suƉƉly or comƉly ǁith a
municiƉal reƋuirement͘ The edžercise is a shortͲterm
cost to C^Ks because they haǀe to Ɖay Ĩor labor and
Ĩuel to transĨer the ǀehicle and earn no reǀenue
51 dhis inĨorŵaƟon ǁas received ƚhrough ǁordͲoĨͲŵouƚh Ĩroŵ ƚhe clienƚ.
hnĨorƚunaƚely͕ conĮdenƟaliƚy reƋuireŵenƚs prevenƚed ƚhe clienƚ Ĩroŵ
revealing ŵore deƚailed inĨorŵaƟon abouƚ ƚhe response ƚo ƚhe Z&W.
5Ϯ DarƟn and ^haheen͕ ͞'reenhouse 'as ŵission /ŵpacƚs oĨ arsharing in
Norƚh ŵerica.͟
ConElusion
^eǀeral themes emerŐe Ĩrom this chaƉter͘ The Įrst is
that some oĨ the Őoals are in conŇict ǁith each other:
22
B O S T O N M AY O R ’ S O F F I C E
Car-Sharing and Public Parking in Boston
Ĩrom rental durinŐ the transĨer Ɖeriod͘ This reƉort
incorƉorates the uncertainty around the imƉacts oĨ
the ͲtoͲ model into its recommendaƟons in the Įnal
chaƉter͘
Table 2 summarinjes the emƉirical conclusions Ĩrom
this chaƉter͘ thile there is some uncertainty reŐardinŐ
the edžact maŐnitude oĨ these imƉacts, this reƉort
is conĮdent that car-sharinŐ ǁill haǀe ďeneĮcial
imƉacts on the City oĨ oston͘ boǀe all, the esƟmated
reducƟon in ǀehicle holdinŐs means that, in the lonŐ
term, residents stand to Őain at least Ĩour ƉarŬinŐ
sƉaces Ĩor eǀery Ɖuďlic ƉarŬinŐ sƉace they lose͘
ZEShLdS
PZ/sAdE sE,/CLE KtEEZS,/P
sMd AE ',' EM/SS/KES
MK/L/dz ACCESS
Cervero
et al
Net reducƟon oĨ ϰͲϳ vehicles ;including
Ĩoregone purchasesͿ
Daily sDd reducƟon oĨ 1.ϴϳͲ
ϳ ŵiles
/ŵproved ʹ ϰϯй
ŵore trips becoŵe
accessible
DarƟn and
^haheen
Net reducƟon oĨ ϰͲϲ vehicles
',' eŵission reducƟon oĨ
Ϭ.5ϴͲϬ.ϴϰ t ','ͬyear
Not studied
Wroũected
iŵpact Ĩor
this report
Net reducƟon oĨ ϰ vehicles ;ϰ vehicles shed͕
1 vehicle purchase Ĩoregone͕ 1 shared car
addedͿ
Daily DsDd reducƟon oĨ
1.ϴϳ ŵiles and ',' eŵission
reducƟon oĨ Ϭ.5ϴ ŵetric tons
per year
/ŵproved
ConĮdence
in proũected
iŵpact
,igh ʹ dhe literature on carͲsharing
consistently Įnds that it causes a staƟsƟcally
signiĮcant reducƟon in private vehicle
oǁnership. dhe reports only diīer on the
ŵagnitude oĨ the reducƟon and this report
uses a conservaƟve esƟŵate.
>oǁ ʹ dhere is evidence
oĨ sDd and ',' eŵission
reducƟons aŵong C^K
ŵeŵbers but very Ĩeǁ
oĨ these results ǁere
staƟsƟcally signiĮcant.
,igh ʹ dhe
evidence supports
the intuiƟve noƟon
that carͲsharing
iŵproves ŵobility
access.
TABLE 2: IMPACTS OF CAR-SHARING ON SELECTED CITY GOALS (BASED ON AVAILABLE EMPIRICAL
EVIDENCE)
B O S T O N M AY O R ’ S O F F I C E
23
Car-Sharing and Public Parking in Boston
Chapter 4:
Recommendations
C
Zͳ^,ZIE' orŐaninjaƟons (C^Ks) haǀe asŬed
the City oĨ oston to allocate Ɖublic ƉarŬinŐ
sƉaces to their shared cars͘ The Įrst Ɖart oĨ
this chaƉter recommends an aƉƉroƉriate resƉonse to
their reƋuest, taŬinŐ into account the Őoals discussed
in ChaƉter 3 and the imƉacts edžamined in ChaƉter 4͘
The second Ɖart oĨ this chaƉter deals ǁith ŐeƫnŐ more
accurate esƟmates oĨ the imƉacts oĨ carͲsharinŐ in
oston͘
The Ɖreǀious chaƉter Ɖroǀides comƉellinŐ eǀidence
that these Őoals are aƩainable throuŐh allocaƟnŐ
some oĨ the city͛s limited Ɖublic ƉarŬinŐ sƉaces to
shared cars͘ there there is uncertainty, it is only
around the edžact maŐnitude, not the edžistence, oĨ the
beneĮts͘ ccordinŐly, this reƉort recommends that the
City oĨ oston aƉƉroach car-sharinŐ as a social and
enǀironmental ďeneĮt and allocate Ɖuďlic ƉarŬinŐ
sƉaces to shared cars͘ 53
4eEommendation AlloEate PubliE
ParMing SRaEes to Shared Cars
To suƉƉort this allocaƟon Ɖolicy, the City oĨ oston
should: 54
In considerinŐ the resƉonse to C^Ks, the City oĨ oston
set the ĨolloǁinŐ Őoals:
1͘ Increase residenƟal Ɖublic ƉarŬinŐ aǀailability
2͘ ImƉroǀe mobility access Ĩor the carless
3͘ Zeduce sehicle Miles Traǀelled (sMT) and
'reenhouse 'as (',') emissions
4͘ Madžiminje reǀenue (or miniminje losses)
» stablish a Ĩormal Ɖrocess Ĩor allocaƟnŐ
Ɖublic ƉarŬinŐ sƉaces to shared ǀehicles͘
C^K enŐaŐement should be administered
by dedicated staī at a deƉartment or subͲ
deƉartment leǀel͘ The sƉaces allocated to
shared cars should be disƟnct Ĩrom sƉaces
allocated Ĩor other uses (i͘e͘ ǁith siŐns and
5ϯ ^usan . ^haheen et al.͕ ͞Carsharing and Wublic Warking Wolicies͗ ssessing
eneĮts͕ Costs͕ and est WracƟces in North ŵerica͕͟ Darch ϮϬ1Ϭ͕ hƩp͗ͬͬ
trid.trb.orgͬvieǁ.aspdž͍idсϵϮϵϮϰϬ.
5ϰ dhese build on the policy recoŵŵendaƟons eleŵents in ^haheen et al.
͞Carsharing and Wublic Warking Wolicies͟.
24
B O S T O N M AY O R ’ S O F F I C E
Car-Sharing and Public Parking in Boston
marŬinŐs), and, iĨ necessary, njoninŐ laǁs should
be amended to reŇect this disƟncƟon͘ ParŬinŐ
enĨorcement oĸcers should ensure that only
shared cars use the desiŐnated sƉaces͘
» Conduct ũoint Ɖublic consultaƟon sessions ǁith
C^Ks ǁhen allocaƟnŐ Ɖublic ƉarŬinŐ sƉaces
in a Őiǀen neiŐhborhood͘ City oĸcials should
Ĩacilitate these sessions͘
» ZeƋuire that any C^K allocated a Ɖublic ƉarŬinŐ
sƉace Őrant the City oĨ oston access to:
o
TriƉͲleǀel data that has been
suĸciently anonyminjed
o
>ocaƟon data Ĩor all oĨ it shared cars
in oston (both in Ɖriǀate and Ɖublic
ƉarŬinŐ sƉaces)
o
ŐŐreŐate data on the number oĨ C^K
members and their characterisƟcs (car
oǁnershiƉ, aŐe, income) Ĩor each oĨ
the 250mdž250m cells in oston
Ɖrecedent has been set Ĩor this ǁith the data
sharinŐ aŐreement betǁeen hber, a rideͲhailinŐ
serǀice, and the City oĨ oston͘55
eyond the consideraƟons aboǀe, a sound allocaƟon
Ɖolicy also needs to determine the aƉƉroƉriate carͲ
sharinŐ model, the sƉaƟal distribuƟon oĨ the allocated
ƉarŬinŐ sƉaces, as ǁell as the Ɖermit Ɖrice, duraƟon,
and ƋuanƟty͘
Which Model?
KĨ the tǁo carͲsharinŐ models, the ͲtoͲ (tǁoͲǁay)
model has been beƩer studied͘ Thus, this reƉort
is more conĮdent in its beneĮts and recommends
ƉrioriƟnjinŐ the allocaƟon oĨ Ɖuďlic ƉarŬinŐ sƉaces
to A-to-A ;tǁo-ǁayͿ shared cars throuŐh edicated
Permits͘5ϲ
Eonetheless, the ͲtoͲ (oneͲǁay) model is an
innoǀaƟon in carͲsharinŐ that holds Őreat Ɖromise͘ &or
the City oĨ oston, the maũor ƉoliƟcal uƉside is that
ͲtoͲ shared cars do not reƋuire a dedicated sƉace͘
55 Nicole Dungca͕ ͞hber to ^hare Zidership Data ǁith oston͕͟
dhe Boston 'loďe͕ :anuary 1ϯ͕ ϮϬ15͕ hƩps͗ͬͬǁǁǁ.bostonglobe.
coŵͬbusinessͬϮϬ15ͬϬ1ͬ1ϯͬuberͲshareͲridershipͲdataͲǁithͲ
bostonͬϰKloϰϬKZtYϳũkoaũoNNͬstory.htŵl.
5ϲ Dedicated Werŵits allocate a public parking space Ĩor a speciĮc C^K͛s
shared car.
B O S T O N M AY O R ’ S O F F I C E
,ence, there is a loǁer liŬelihood oĨ oƉƉosiƟon Ĩrom
residents due to the loss oĨ a Ɖublic ƉarŬinŐ sƉace͘
,oǁeǀer, the model͛s noǀelty and Ňedžibility also means
that there is Őreater uncertainty about its imƉacts͘
ThereĨore, this reƉort recommends the City oĨ oston
adoƉt a more conserǀaƟǀe Ɖolicy in issuinŐ &ree&loaƟnŐ ParŬinŐ Permits5ϳ as to ďeƩer examine the
imƉacts oĨ the A-to- model͘ In liŐht oĨ this, the 150
&reeͲ&loaƟnŐ ParŬinŐ Permits oīered in the ZeƋuest Ĩor
ProƉosals (Z&P) are a Őood start͘ The nedžt steƉ ǁould
be to edžamine the data Ĩrom the C^K, ƉarƟcularly triƉͲ
leǀel data, to looŬ at the imƉacts on mobility as ǁell as
sMT and ',' emissions͘
Where?
shared car needs to be Ɖlaced in the riŐht Ɖlace
to haǀe the desired imƉact͘ &or edžamƉle, a shared
car is unliŬely to reduce ǀehicle oǁnershiƉ (and
increase Ɖublic ƉarŬinŐ aǀailability) in a Őiǀen area iĨ
it is an hour͛s ǁalŬ aǁay͘ ,ence, the allocated Ɖublic
ƉarŬinŐ sƉaces must be located ǁhere they madžiminje
reducƟons in ǀehicle oǁnershiƉ or increase mobility
access͘ &or these imƉacts to occur, allocated Ɖuďlic
ƉarŬinŐ sƉaces cannot ďe more than ϰ00 meters aǁay
Ĩrom the tarŐet user ŐrouƉ͘5ϴ
It cannot be assumed that the Őoals oĨ C^Ks aliŐn
ƉerĨectly ǁith those oĨ the City oĨ oston ǁhen it
comes to choosinŐ the locaƟon oĨ Ɖublic ƉarŬinŐ sƉaces
Ĩor shared cars͘ n edžamƉle oĨ Ɖoor Őoal aliŐnment
miŐht be the Ɖlacement oĨ a shared car in an area
resulƟnŐ in reduced Ɖublic transƉortaƟon usaŐe and
increased sMTs͘ Conǀersely, it ǁould also be unǁise
Ĩor the City oĨ oston to micromanaŐe the Ɖrocess
by determininŐ the edžact locaƟons Ĩor Ɖublic ƉarŬinŐ
sƉaces Ĩor the C^Ks and oīerinŐ it to them on a taŬeͲitͲ
orͲleaǀeͲit basis͘ ^ome areas miŐht not be suĸciently
ƉroĮtable Ĩor a C^K͘
This reƉort recommends a midƉoint on the sƉectrum:
the City oĨ oston associates Őoals ǁith a set oĨ
ŐeoŐraƉhical areas and alloǁs the CSK to choose their
Ɖuďlic ƉarŬinŐ sƉaces Ĩrom those sets͘ &or edžamƉle, in
order to increase Ɖublic ƉarŬinŐ aǀailability, the City oĨ
5ϳ &reeͲŇoaƟng Warking Werŵits alloǁ a shared car to be parked in any
legal public parking space. ddiƟonally͕ the shared car and ŵotorist are not
subũect to ŵeter payŵent or Ɵŵe liŵit restricƟons and residenƟal parking
perŵit restricƟons.
5ϴ :arreƩ talker͕ ͞asics͗ talking Distance to dransit͕͟ ,uŵan dransit͕ pril
Ϯϰ͕ ϮϬ11͕ hƩp͗ͬͬǁǁǁ.huŵantransit.orgͬϮϬ11ͬϬϰͬbasicsͲǁalkingͲdistanceͲtoͲ
transit.htŵl.
25
Car-Sharing and Public Parking in Boston
oston idenƟĮes 250dž250m cells ǁhere there are many
Ɖriǀate ǀehicles and lets the C^K choose Ɖublic ƉarŬinŐ
sƉaces ǁithin any oĨ the cells͘ The city͛s Z&P aƉƉlied
this recommendaƟon ǁith the addiƟonal sƟƉulaƟon
that access to certain areas ǁas conƟnŐent uƉon
ƉlacinŐ cars to meet Őoals in others͘
/ŶĐƌĞĂƐŝŶŐWƵďůŝĐWĂƌŬŝŶŐǀĂŝůĂďŝůŝƚLJdŚƌŽƵŐŚ
ZĞĚƵĐƟŽŶƐŝŶsĞŚŝĐůĞKǁŶĞƌƐŚŝƉ
C^K members haǀe diǀerse reasons Ĩor sheddinŐ
ǀehicles they oǁn includinŐ edžisƟnŐ ǀehicles beinŐ
close to reƟrement,5ϵ enǀironmental concerns, and
a shared car beinŐ more economical than a Ɖriǀate
ǀehicle beloǁ certain mileaŐes͘ϲ0 The Įnal reason
imƉlies that there are mileaŐes Ĩor ǁhich aǀeraŐe cost
oĨ shared car usaŐe are eƋual to or loǁer than the
aǀeraŐe cost oĨ usinŐ a Ɖriǀate ǀehicle͘
In their study oĨ the imƉacts oĨ carͲsharinŐ in Eorth
merica, MarƟn et al͘ Ĩound that ϵ0й oĨ ǀehicles shed
ǁere driǀen less than 1ϲ,000 miles a year and the
median mileaŐe on shed ǀehicles ǁas ϳ,000 miles a
year͘ϲ1 hsinŐ motorinŐ cost data Ĩrom , another
reƉort suŐŐests that usinŐ a shared car is more costͲ
eīecƟǀe than oǁninŐ a ǀehicle at mileaŐes beloǁ
5,000 miles a year͘ϲ2 This reƉort assumes that Ɖriǀate
ƉassenŐer ǀehicles driǀen less than ϲ,000 miles a year
are the main candidates Ĩor reƉlacement ďy a shared
car͘
The maƉ in &iŐure ϴ draǁs on data Ĩrom the
MassachuseƩs sehicle Census and shoǁs the count oĨ
loǁͲmileaŐe ƉassenŐer ǀehicles Őeocoded to a Őiǀen
250mdž250m cell in the Ĩourth Ƌuarter oĨ 2011͘ The
census deĮnes loǁͲmileaŐe ǀehicles as those that are
driǀen (on aǀeraŐe) under 1ϲ miles a day or 5,ϴ44
miles Ɖer year͘ ͞,oƩer͟ cells, denoted by deeƉer hues
oĨ red, haǀe hiŐher number oĨ loǁͲmileaŐe ǀehicles
than ͞cooler͟ cells, denoted by liŐht shades oĨ yelloǁ͘
The numbers in the cells are the count oĨ loǁͲmileaŐe
ǀehicles in that cell͘
ThereĨore, to increase Ɖuďlic ƉarŬinŐ aǀailaďility, the
City oĨ oston should allocate Ɖuďlic ƉarŬinŐ sƉaces
ǁithin ϰ00 meters oĨ cells ǁith three or more ǀehicles
5ϵ DarƟn͕ ^haheen͕ and >idicker͕ ͞/ŵpact oĨ Carsharing on ,ousehold
sehicle ,oldings͗ Zesults Ĩroŵ a North ŵerican ^haredͲhse sehicle ^urvey.͟
ǁith mileaŐes ďeloǁ 1ϲ miles a day ;loǁ-mileaŐe
ǀehiclesͿ͘
Kne caǀeat is that this ǀehicle census data is oǀer Ĩour
years old and those loǁ mileaŐe ǀehicles may no lonŐer
edžist͘ This issue is miƟŐated by tǁo Ĩactors͘ &irst, there
is a stronŐ correlaƟon betǁeen the number oĨ loǁ
mileaŐe ǀehicles and the number oĨ Ɖriǀate ǀehicles
(see &iŐure 1) in a Őiǀen cell͘ ^econd, cells ǁith many
Ɖriǀate ǀehicles in a Őiǀen year also haǀe many Ɖriǀate
ǀehicles in other years͘ Put another ǁay, the Ɖublic
ƉarŬinŐ shortaŐe in a Őiǀen area Ɖersists throuŐh Ɵme͘
ThereĨore, the number oĨ loǁ mileaŐe ǀehicles in the
Ĩourth Ƌuarter oĨ 2011 is an aƉƉroƉriate Ɖrodžy Ĩor the
current number oĨ loǁ mileaŐe ǀehicles͘
/ŵƉƌŽǀŝŶŐDŽďŝůŝƚLJĐĐĞƐƐ
To determine the areas that ǁould Őain the most
mobility Ĩrom the addiƟon oĨ a shared car, this reƉort
Įrst inǀerted the mobility score data Ĩrom &iŐure 2͘ It
then remoǀed the unƉoƉulated cells such as ƉarŬs, the
oston ,arbor Islands, and >oŐan InternaƟonal irƉort
Ĩrom the data set to Ɖroduce &iŐure ϵ͘ The cells ǁith
deeƉer shades oĨ blue haǀe hiŐher immobility scoresϲ3
(i͘e͘ Ɖoorer mobility)͘ Puďlic ƉarŬinŐ sƉaces should
ďe allocated to shared cars ǁithin ϰ00 meters oĨ cells
ǁith immoďility scores in the toƉ ƋuinƟle ;i͘e͘ Őreater
than 0͘ϰ5ϳͿ͘
,oǁ Much and Ĩor ,oǁ lonŐ?
s stated in the Ɖreǀious chaƉter, all ϴ0 edicated
Permits (ǁith a madžimum oĨ 40 Ɖer C^K) and 150
&reeͲ&loaƟnŐ Permits oīered in the city͛s Z&P ǁere
aƉƉlied Ĩor͘ This imƉlies that the Ɖrice set Ĩor the
Ɖermits ǁas at or beloǁ the Ɖrice C^Ks ǁere ǁillinŐ to
Ɖay͘ The Ɖermits ǁere Ɖriced at Ψ3,500 Ĩor a dedicated
doǁntoǁn sƉace (or a &reeͲ&loaƟnŐ Permit) and
Ψ2,ϳ00 Ĩor a dedicated sƉace elseǁhere͘ϲ4 These Ɖrices
are close to the city͛s esƟmated cost oĨ maintaininŐ an
onͲstreet Ɖublic ƉarŬinŐ sƉace͘
ǀen thouŐh the city can ƉotenƟally charŐe a hiŐher
Ɖrice, reǀenue ŐeneraƟon also has the loǁest Ɖriority
amonŐ the City oĨ oston͛s Őoals͘ More imƉortant,
hiŐher Ɖrices could dissuade C^Ks Ĩrom ƉlacinŐ cars in
oston in the Ĩuture, decreasinŐ the maŐnitude oĨ the
associated beneĮts͘ ThereĨore, this reƉort recommends
ϲϬ DillardͲall͕ dCZW ZeƉort ϭϬϴ͗ Car-Sharing͗ there and ,oǁ /t SuĐĐeeds.
ϲ1 DarƟn͕ ^haheen͕ and >idicker͕ ͞/ŵpact oĨ Carsharing on ,ousehold
sehicle ,oldings͗ Zesults Ĩroŵ a North ŵerican ^haredͲhse sehicle ^urvey.͟
ϲϮ DillardͲall͕ dCZW ZeƉort ϭϬϴ͗ Car-Sharing͗ there and ,oǁ /t SuĐĐeeds.
26
ϲϯ /ŵŵobility ^core с 1 ͬ Dobility ^core
ϲϰ oston dransportaƟon Departŵent͕ ͞Driveoston͗ ZeƋuest Ĩor Wroposals
Ĩor a oston sehicle ^haring Wrograŵ.͟
B O S T O N M AY O R ’ S O F F I C E
Car-Sharing and Public Parking in Boston
FIGURE 8: VEHICLES WITH LOW MILEAGE (BELOW 16 MILES PER DAY) IN A CELL
B O S T O N M AY O R ’ S O F F I C E
27
Car-Sharing and Public Parking in Boston
FIGURE 9: IMMOBILITY SCORES
28
B O S T O N M AY O R ’ S O F F I C E
Car-Sharing and Public Parking in Boston
the City oĨ oston retain the ƉricinŐ scheme Ĩrom its
Z&P͘ >ooŬinŐ ahead, the City oĨ oston should also
consider loǁerinŐ the Ɖermit Ɖrices iĨ C^Ks beŐin to
demand Ĩeǁer sƉaces͘ This is esƉecially true iĨ the City
oĨ oston belieǀes that the madžimum beneĮts Ĩrom
carͲsharinŐ haǀe not yet materialinjed͘
Cerǀero et al Ĩound that the imƉacts oĨ carͲsharinŐ
on reducinŐ Ɖriǀate ǀehicle oǁnershiƉ only started
to maniĨest aŌer tǁo years͘ϲ5 lthouŐh the City oĨ
oston should eǀentually ǀeriĨy this duraƟon ǁith its
oǁn study (nedžt recommendaƟon), in the interim, this
reƉort recommends that shared-car Ɖuďlic ƉarŬinŐ
Ɖermits haǀe tǁo-year duraƟons͘
,oǁ Many?
eyond the sƉaces oīered in the Z&P, this reƉort
recommends an incremental aƉƉroach to allocaƟnŐ
addiƟonal Ɖuďlic ƉarŬinŐ sƉaces to shared cars
;i͘e͘ allocate, eǀaluate, allocateͿ͘ This should be
imƉlemented on an annual basis as Ĩolloǁs: ϲϲ
1͘ llocate a small number (no more than 50) oĨ
Ɖublic ƉarŬinŐ sƉaces to shared cars Ĩrom a C^K͘
2͘ ǀaluate the C^K based on a set oĨ metrics͘ Where
necessary, the C^K is edžƉected to Ɖroǀide the
releǀant data͘ The metrics are as Ĩolloǁs:
a͘ ZelaƟǀe to neiŐhborhoods ǁith Ĩeǁer (or no)
shared cars in Ɖublic ƉarŬinŐ sƉaces, there
should be larŐer decreasesͬsmaller increases in
the number oĨ residenƟal ƉarŬinŐ Ɖermits that
are aƉƉlied Ĩor in comƉarable neiŐhborhoods
ǁith more shared cars͘ϲϳ &or edžamƉle, iĨ more
shared cars are Ɖlaced in llston than in
riŐhton in 2015, the diīerence in number oĨ
residenƟal Ɖermits that are aƉƉlied Ĩor betǁeen
2015ͬ201ϲ and 2014ͬ2015 Ĩor llston should
be less than riŐhton͛s diīerence oǀer the
same Ɖeriod͘ IĨ the data is aǀailable, a similar
aƉƉroach can be used Ĩor car oǁnershiƉ, sMT,
and ',' emissions͘
b͘ There should be an increase in C^K membershiƉ
ϲ5 Cervero and dsai͕ ͞City Car^hare in ^an &rancisco͕ CaliĨornia.͟
ϲϲ dhis approach is a variant oĨ the one adopted by the tashington D.C.͛s
District Departŵent oĨ dransportaƟon in its policy Ĩor allocaƟng public spaces
to shared cars. ^aŵ iŵbabǁe͕ ssociate Director oĨ the Wolicy͕ Wlanning Θ
^ustainability dŵinistraƟon͕ provided this inĨorŵaƟon.
ϲϳ dhis is a diīerenceͲinͲdiīerence calculaƟon ǁithout the staƟsƟcal
ŵachinery.
B O S T O N M AY O R ’ S O F F I C E
in the areas around the allocated sƉaces͘
c͘ The number oĨ ƉarŬinŐ inĨracƟons that a shared
car is inǀolǀed ǁhen outside its desiŐnated
sƉace in should be loǁ͘
d͘ The maũority oĨ sharedͲcar uƟlinjaƟon should
occur in oīͲƉeaŬ Ɖeriods͘
3͘ In the ĨolloǁinŐ year, iĨ the metrics in ^teƉ 2
aƉƉear to be met or edžceeded, start aŐain at ^teƉ
1͘
The ƉracƟcal and ƉoliƟcal limitaƟons oĨ conǀerƟnŐ
edžisƟnŐ residenƟal Ɖublic ƉarŬinŐ sƉaces only Ĩurther
buƩress the case Ĩor this aƉƉroach͘
4eEommendation ConduEt an
+ndeRendent +mRaEt Study
The City oĨ oston can siŐniĮcantly reduce the
deŐree oĨ uncertainty associated ǁith the imƉacts
oĨ carͲsharinŐ by studyinŐ it ǁithin oston͘ To do
so, this reƉort recommends that the City oĨ oston,
in ƉartnershiƉ ǁith CSKs, conduct a larŐe-scale
randominjed exƉeriment oǀer a Ĩour-year Ɖeriod͘
Instead oĨ the allocaƟon Ɖolicy Ĩrom the Ɖreǀious
recommendaƟon, C^Ks ƉarƟciƉaƟnŐ in this study ǁill
Ĩolloǁ the allocaƟon Ɖrocess in the study desiŐn͘
The unit oĨ analysis Ĩor this study ǁill be a household͘
The causal relaƟonshiƉ oĨ interest is the imƉact oĨ the
number oĨ shared cars near a Őiǀen household on:
» The number oĨ Ɖriǀate ǀehicles oǁned by the
household as ǁell as their aƩributes (e͘Ő͘ year,
maŬe, model, Ĩuel eĸciency)͖
» The household͛s aǀeraŐe daily ǀehicle miles
traǀelled and ',' emissions͖
» The number oĨ C^K members in the household͘
Zandom assiŐnment is as Ĩolloǁs: The ƉarƟciƉaƟnŐ
C^Ks ƉicŬ ϴ0 cells (Ĩrom the Őrid in &iŐure 13) to Ɖlace
shared cars͘ There needs to be a tǁoͲcell ŐaƉ betǁeen
each chosen cell to limit crossoǀer eīects͘ The selected
cells are then matched into Ɖairs based on the deŐree
to ǁhich they share characterisƟcs that could imƉact
the outcomes (e͘Ő͘ ƉoƉulaƟon density, aǀeraŐe
income)͘ In each oĨ these Ɖairs, one cell is randomly
chosen to be in the treatment arm ǁhile the other is
in the control arm, Ĩor a total oĨ 40 cells in each arm oĨ
the study͘
29
Car-Sharing and Public Parking in Boston
C^Ks ǁill only be allocated Ɖublic ƉarŬinŐ sƉaces
in cells Ĩrom the treatment arm͘ Eo sƉaces ǁill be
allocated to C^Ks in the cells Ĩrom the control arm͘ &or
the duraƟon oĨ the edžƉeriment, ƉarƟciƉaƟnŐ C^Ks are
Ɖrohibited Ĩrom ƉlacinŐ addiƟonal shared cars in Ɖublic
and Ɖriǀate ƉarŬinŐ sƉaces inside a control cell and
the tǁoͲcell ͞border͟ around it͘ This is also to Ɖreǀent
crossoǀer eīects͘ ,oǁeǀer, C^Ks may Ɖlace shared
cars in Ɖriǀate ƉarŬinŐ sƉaces ǁithin or around the
treatment cells Ɖroǀided they noƟĨy the City oĨ oston
and do not ǀiolate the Ɖreǀious restricƟon͘
the MassachuseƩs eƉartment oĨ TransƉortaƟon), the
outcome ǀariables aboǀe are edžamined Ĩor households
in both arms͘ This occurs beĨore the study starts and at
the end oĨ the Ĩour years͘
The restricƟon around the control cells miŐht dissuade
C^Ks Ĩrom ƉarƟciƉaƟnŐ in the edžƉeriment͘ To remedy
this, the City oĨ oston should only allocate Ɖublic
ƉarŬinŐ sƉaces to ƉarƟciƉaƟnŐ C^Ks Ĩor the duraƟon oĨ
the edžƉeriment͘ To Ĩurther incenƟǀinje ƉarƟciƉaƟon, the
City oĨ oston should be ǁillinŐ to allocate more Ɖublic
ƉarŬinŐ sƉaces at a cheaƉer Ɖrice in the treatment
cells͘
Kne limitaƟon oĨ this desiŐn is that it only Ɖroǀides
insiŐht into the imƉacts oĨ the ͲtoͲ model oĨ carͲ
sharinŐ͘ ^ince the ͲtoͲ model oĨ carͲsharinŐ does
not limit a shared car to a sinŐle locaƟon, this method
oĨ aƩribuƟon is not aƉƉlicable͘ That said, the insiŐhts
Ĩrom this study ǁill alloǁ the City oĨ oston to be
beƩer inĨormed on the imƉacts oĨ carͲsharinŐ and
ǁhether they meet the city͛s Őoals͘
The causal eīect ǁill be the diīerence in the chanŐes
in the outcome ǀariables in these tǁo Ɵme Ɖeriods
betǁeen households in the tǁo arms oĨ the study (i͘e͘
diīerenceͲinͲdiīerence)͘ ͞ƉƉendidž ,: ^tudy Protocol
to džamine the ImƉacts oĨ CarͲ^harinŐ in oston͟
Ɖroǀides a Ĩull edžƉlanaƟon oĨ the study desiŐn͘
hsinŐ ǀehicle reŐistry and insƉecƟon records Ĩrom the
MassachuseƩs ZeŐistry oĨ Motor sehicles (a diǀision oĨ
30
B O S T O N M AY O R ’ S O F F I C E
Car-Sharing and Public Parking in Boston
Appendices
Appendices
B O S T O N M AY O R ’ S O F F I C E
31
Car-Sharing and Public Parking in Boston
AƉƉendix A͗ oston EeiŐhďorhoods
FIGURE 10: CITY OF BOSTON NEIGHBORHOODS
32
B O S T O N M AY O R ’ S O F F I C E
Car-Sharing and Public Parking in Boston
AƉƉendix ͗ Car-sharinŐ KrŐaninjaƟons ;CSKsͿ
EAME
LKCAd/KE MKEL
CAZͳ
KtEEZS,/P
MKEL
ACd/sE /E
KSdKE
ipcar
;hƩp͗ͬͬǁǁǁ.njipcar.coŵͬͿ
Dostly ͲtoͲ͕
edžperiŵenƟng ǁith
ͲtoͲ
&leet oǁned
zes
CarϮ'o
;hƩps͗ͬͬǁǁǁ.carϮgo.coŵͬenͬͿ
ͲtoͲ
&leet oǁned
No
'etaround
;hƩps͗ͬͬǁǁǁ.getaround.coŵͬͿ
ͲtoͲ
WeerͲtoͲpeer
No
ZelayZides
;hƩps͗ͬͬrelayrides.coŵͬͿ
ͲtoͲ
WeerͲtoͲpeer
zes
nterprise
ͲtoͲ
&leet Kǁned
zes
B O S T O N M AY O R ’ S O F F I C E
33
Car-Sharing and Public Parking in Boston
AƉƉendix C͗ ,ouseholds and sehicle KǁnershiƉ
FIGURE 11: VEHICLES PER HOUSEHOLD
34
B O S T O N M AY O R ’ S O F F I C E
Car-Sharing and Public Parking in Boston
FIGURE 12: NUMBER OF HOUSEHOLDS IN A CELL
B O S T O N M AY O R ’ S O F F I C E
35
Car-Sharing and Public Parking in Boston
AƉƉendix ͗ Studies on /mƉacts oĨ Car-SharinŐ
Sdhz
ZE'/KE
ΈzEAZΉ
sE,/CLES
S,E PEZ
S,AZE
CAZ
sMd AE
','
EM/SS/KE
C,AE'ES
SAMPLE
S/E
MEd,KKLK'z
sAL//dz
ϮϲϮ
eĨoreͲandͲaŌer
survey
Doderate
Clayton >ane.
WhillyCar^hare͗ &irstͲ
zear ^ocial and Dobility
/ŵpacts oĨ Carsharing
in Whiladelphia͕
Whiladelphia͕
W ;ϮϬϬϯͿ
Ϯϯ
ZeducƟon
oĨ several
hundred sDd
per ŵonth
Zichard Katnjev.
Car^haring Wortland͗
Zevieǁ and nalysis oĨ
/ts &irst zear
Wortland͕ KZ
;1ϵϵϵͿ
3.5
No change
ϲϰ
eĨoreͲandͲaŌer
survey
Doderate
dCZW Zeport 1Ϭϴ͗ CarͲ
^haring͗ there and hoǁ
it succeeds
North
ŵerica
;ϮϬϬϰͿ
13.9
Nͬ
1͕3ϰϬ
eĨoreͲandͲaŌer
survey
>oǁ
lliot DarƟn͕ ^usan
^haheen͕ :eīrey >idicker.
/ŵpact oĨ Carsharing
on ,ousehold sehicle
,oldings͗ Zesults Ĩroŵ a
North
ŵerica
;ϮϬϬϴͿ
ϰͲϲ͖ 9Ͳ13
;including
Ĩoregone
purchasesͿ
Nͬ
ϲ͕Ϯϴ1
eĨoreͲandͲ
aŌer survey
ʹ controlled Ĩor
conĨounders
,igh
lliot DarƟn͕ ^usan
^haheen. 'reenhouse
'as ŵission /ŵpacts
oĨ Carsharing in North
ŵerica
North
ŵerica
;ϮϬϬϴͿ
Nͬ
ZeducƟon oĨ
Ϭ.5ϴ to Ϭ.ϴϰ
ŵetric tons per
year
ϲ͕Ϯϴ1
eĨoreͲandͲ
aŌer survey
ʹ controlled Ĩor
conĨounders
,igh
Zobert Cervero. City
Car^hare͗ &irstͲyear
travel deŵand iŵpacts
^an &rancisco͕
C ;ϮϬϬ1Ϳ
None
ϮϮϬ
DatchedͲpair
analysis ǁith a
treatŵent and
control group
,igh
Zobert Cervero͕ zuhsin
dsai. City Car^hare
in ^an &rancisco͕
CaliĨornia͗ ^econdͲzear
dravel Deŵand and Car
^an &rancisco͕
C ;ϮϬϬ3Ϳ
ϲ͖ ϳ
;including
Ĩoregone
purchasesͿ
None
516
DatchedͲpair
analysis ǁith a
treatŵent and
control group
,igh
5
DodeͲadũusted
sDd reducƟon
1.ϴϳ ŵiles
per day͖ C^K
ŵeŵbers
5ϳϮ
DatchedͲpair
analysis ǁith a
treatŵent and
control group
,igh
Zobert Cervero͕ aron
'olub͕ rendan Nee. City
Car^hare͗ >ongerͲderŵ
dravel Deŵand and Car
Kǁnership /ŵpacts
36
^an &rancisco͕
C ;ϮϬϬ5Ϳ
None
B O S T O N M AY O R ’ S O F F I C E
Car-Sharing and Public Parking in Boston
AƉƉendix E͗ etailed Zeǀieǁ oĨ Shortlisted Studies on /mƉacts oĨ Car-sharinŐ
&or all studies, staƟsƟcal siŐniĮcance ǁas set at the 5й Ɖrobability leǀel͘
MarƟn͖ ^haheen͖ >idicŬer͘ CarsharinŐ͛s ImƉact Kn ,ousehold Car ,oldinŐs: Zesults Ĩrom a
Eorth merican ^haredͲhse sehicle ^urǀey (March 2010)
DĞƚŚŽĚŽůŽŐLJ
Ten maũor C^Ks oƉeraƟnŐ in Eorth merica sent an email to all members inǀiƟnŐ them to taŬe an online surǀey
that oƉened in ^eƉtember and closed on Eoǀember ϳ, 200ϴ͘ The surǀey ƋuesƟonnaire used ƋuesƟons to Ĩacilitate
͞beĨoreͲandͲaŌer͟ analysis͘ &or ǀehicle sheddinŐ, it asŬed resƉondents about the chanŐes in household ǀehicle
oǁnershiƉ͘ ntry into a draǁ Ĩor Ψ100 ǁorth oĨ carͲsharinŐ credit ǁas Ɖroǀided as an incenƟǀe Ĩor resƉonses͘
The ƉoƉulaƟon oĨ interest ǁas all C^K members in Eorth merica and the Įnal samƉle sinje ǁas ϲ,2ϴ1 indiǀiduals͘
The Įnal samƉle edžcluded tǁo marŬets: colleŐe and edžclusiǀe businessͬŐoǀernment use because the surǀey ǁas
Ĩocused on the residenƟal or neiŐhborhood carͲsharinŐ models͘ The study also assiŐned njero imƉacts to selĨͲ
idenƟĮed inacƟǀe members͘
To handle ƉotenƟal conĨounders, ƋuesƟons ǁere included to idenƟĨy Ĩactors such as home or ǁorŬƉlace moǀes
that had imƉacts on traǀel ƉaƩerns͘ ZesƉondents ǁho ansǁered in the aĸrmaƟǀe to such ƋuesƟons ǁere edžcluded
Ĩrom the Įnal samƉle͘
Results
Within the samƉle oĨ ϲ,2ϴ1 indiǀiduals, a net (includinŐ increases in ǀehicle oǁnershiƉ) oĨ 1,4ϲ1 ǀehicles ǁere shed͘
monŐ h^ resƉondents, oǁnershiƉ ǁent Ĩrom 0͘55 ǀehicles Ɖer household ͞beĨore͟ carͲsharinŐ to 0͘2ϵ ǀehicles Ɖer
household aŌer, a reducƟon oĨ almost 50й͘
To determine industryͲǁide imƉacts oĨ carsharinŐ, the researchers Ɖroũected the results Ĩrom the samƉle on the
industry in :uly 200ϵ (3ϳϴ,000 members and ϵ,ϴ1ϴ ǀehicles)͘ This edžtraƉolaƟon ǁas done usinŐ the ĨolloǁinŐ
Ĩormula:
sehiĐles Shed Ɖer Shared Car с ΂΀;ϭϬϬй - /naĐƟǀe Share йͿ Ύ 3ϭϰ͕3ϵϬ ͬ 6͕Ϯϴϭ΁ Ύ ϭ͕ϰ6ϭ΃ ͬ ϵ͕ϴϭϴ
The 314,3ϵ0 is the number oĨ households that is deriǀed by scalinŐ the 3ϳϴ,000 membershiƉ doǁn by ϴй (the
ƉroƉorƟon business, Őoǀernment, and colleŐe members in the samƉle) then adũusƟnŐ that ĮŐure Ĩor the 1ϵй oĨ
resƉondents in the samƉle ǁho belonŐed to household ǁith tǁo C^K members͘ hsinŐ sensiƟǀity analysis ǁhere
the share oĨ inacƟǀe members is assumed to be betǁeen 15й and 40й across the enƟre membershiƉ, the number
oĨ ǀehicles shed is esƟmated to be betǁeen 4 and ϲ Ɖer shared car͘ IĨ ĨoreŐone Ɖurchases are included, this number
rises to ϵ to 13 Ɖer shared car͘
ssessŵeŶt
There are issues ǁith the internal ǀalidity oĨ the study in terms oĨ the claim that ǀehicle sheddinŐ ǁas caused by
beinŐ an acƟǀe C^K member͖ it is unclear iĨ the members ǁould not haǀe sold their cars eǀen iĨ they hadn͛t ũoined
a C^K͘ The study claims that researchers asŬed ƋuesƟons to idenƟĨy conĨoundinŐ Ĩactors or eǀents and remoǀed
resƉonses Ĩrom the analysis iĨ either ǁas Ĩound͘ ,oǁeǀer, the deŐree to ǁhich this reduced omiƩed ǀariable bias is
uncertain͘ The edžtraƉolaƟon oĨ samƉle data to the larŐer ƉoƉulaƟon could also ƉotenƟally be ƉroblemaƟc͘
That said, the study is relaƟǀely sound methodoloŐically and is the larŐest (in terms oĨ samƉle sinje) study oĨ carͲ
sharinŐ͘
B O S T O N M AY O R ’ S O F F I C E
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Car-Sharing and Public Parking in Boston
MarƟn͖ ^haheen͘ 'reenhouse 'as mission ImƉacts oĨ CarsharinŐ in Eorth merica
(December 2011)
DetŚŽĚŽlŽŐLJ
The study emƉloyed the methodoloŐy and data Őathered Ĩrom ͞CarsharinŐ͛s ImƉact Kn ,ousehold Car ,oldinŐs:
Zesults Ĩrom a Eorth merican ^haredͲhse sehicle ^urǀey͘͟ It edžamined tǁo imƉacts͘ The Įrst ǁas the obserǀed
imƉact, ǁhich ǁas the Ɖhysically measurable emission chanŐe that resulted Ĩrom chanŐes in driǀinŐ behaǀior
Ĩor a household ǁith C^K members͘ The second imƉact ǁas described as the ͞ĨullͲimƉact͘͟ This reƉresented the
esƟmated chanŐe in emissions due to ĨoreŐone triƉs͘ The study assumes that these ĨoreŐone triƉs ǁould haǀe been
made iĨ the household had not reduced its ǀehicle holdinŐs due to carͲsharinŐ͘
Results
The esƟmated obserǀed reducƟon in ',' emissions ǁas 0͘5ϴ metric tons Ɖer year Ĩor member households͘ The
Ĩull imƉact ǁas esƟmated to be a reducƟon 0͘ϴ4 metric tons Ɖer year͘ oth oĨ these esƟmates ǁere staƟsƟcally
siŐniĮcant͘
ssessŵeŶt
ZeĨer to the assessment oĨ ͞CarsharinŐ͛s ImƉact Kn ,ousehold Car ,oldinŐs: Zesults Ĩrom a Eorth merican
^haredͲhse sehicle ^urǀey͘͟
Cerǀero͘ City Car^hare: &irstͲzear Traǀel Demand ImƉacts (Eoǀember 2002)
The study analynjes three surǀeys administered to members and nonͲmembers oǀer the Įrst year oĨ City Car^hare͛s
oƉeraƟon in ^an &rancisco, the Įrst oĨ ǁhich occurred betǁeen midͲ&ebruary and earlyͲMarch 2001 beĨore City
Car^hare͛s launch͘ The remaininŐ surǀeys ǁere administered 3Ͳ4 months and ϴͲϵ months into the ƉroŐram͘
DetŚŽĚŽlŽŐLJ
The study emƉloyed a matchedͲƉair analyƟcal aƉƉroach ǁith a treatment (i͘e͘ members) and control ŐrouƉ (i͘e͘
nonͲmembers)͘ The control ŐrouƉ, reĨerred to as nonͲmembers, consisted oĨ indiǀiduals ǁho had reŐistered Ĩor City
Car^hare, but had not Ĩormally ũoined as there ǁas no PKD in their neiŐhborhood͘ The treatment ŐrouƉ, reĨerred
to as members, consisted oĨ those ǁho had Ĩormally ũoined͘ ^amƉle sinjes Ĩor the three surǀeys ǁere 143 members
and 155 nonͲmembers Ĩor the Įrst, 105 members and ϵ4 nonͲmembers Ĩor the second, 131 members and ϴϵ nonͲ
members Ĩor the third͘
Results
In terms oĨ sMTs, the surǀey shoǁed an increase in the sMTs oĨ members͘ This ǁas aƩributed to the maũority oĨ
members not oǁninŐ Ɖriǀate ǀehicles and increasinŐ their sMTs as they added a shared car to their transƉortaƟon
midž͘ ,oǁeǀer, this increase ǁas not staƟsƟcally siŐniĮcant͘ Eo siŐniĮcant chanŐe in ǀehicle oǁnershiƉ as obserǀed,
althouŐh this is aƩributed to the carͲsharinŐ ƉroŐram beinŐ relaƟǀely neǁ͘
ssessŵeŶt
ZeĨer to combined assessment in ͞City Carshare: >onŐͲTerm Traǀel Demand and Car KǁnershiƉ ImƉacts͟ beloǁ͘
Cerǀero͖ Tsai͘ ^an &rancisco City Car^hare: ^econdͲzear traǀel Demand and Car KǁnershiƉ
ImƉacts
The second in the series oĨ studies on City Car^hare to edžamine its imƉacts tǁo years aŌer it ǁas launched͘ Its data
ǁas draǁn Ĩrom Ĩourth surǀey ǁas conducted on members and nonͲmembers (i͘e͘ the staƟsƟcal control ŐrouƉ) in
earlyͲtoͲmid March 2003͘
38
B O S T O N M AY O R ’ S O F F I C E
Car-Sharing and Public Parking in Boston
DetŚŽĚŽlŽŐLJ
This study conƟnued to emƉloy the same matchedͲƉair analyƟcal aƉƉroach in Zobert Cerǀero͛s ͞City Car^hare:
&irstͲzear Traǀel Demand ImƉacts͟ ǁith a samƉle sinje oĨ 4ϲ2 members and 54 nonͲmembers͘
Results
Knce aŐain, no staƟsƟcally siŐniĮcant decline in sMTs Ĩor members relaƟǀe to nonͲmembers ǁas detected͘
,oǁeǀer, membershiƉ did increase the liŬelihood oĨ sheddinŐ a ǀehicle or ĨoreŐoinŐ the Ɖurchase oĨ one͘ This
result ǁas staƟsƟcally siŐniĮcant at a 5й Ɖrobability leǀel͘ &or the tyƉical surǀey resƉondent (i͘e͘ nonͲ,isƉanic liǀinŐ
ǁith unrelated adults in a household ǁith 0͘3 cars Ɖer member), a member ǁas 2ϳ ƉercentaŐe Ɖoints more liŬely to
shed a ǀehicle or aǀoid Ɖurchase than a nonͲmember͘ roadly sƉeaŬinŐ, ϲ out 25 member households Őiǀe uƉ a car
ǁithin tǁo years, ǁhile 1 in 25 nonͲmember household added a car in the tǁo years oĨ the ƉroŐram͘ ThereĨore, a
City Car^hare ǀehicle taŬes ϳ (ϲ shed, 1 aǀoided) ǀehicles oī the road͘
ssessŵeŶt
ZeĨer to combined assessment in ͞City Carshare: >onŐͲTerm Traǀel Demand and Car KǁnershiƉ ImƉacts͟ beloǁ͘
Cerǀero͖ 'olub͖ Eee͘ City Carshare: >onŐͲTerm Traǀel Demand and Car KǁnershiƉ ImƉacts
(200ϳ)
The third (and Įnal) in the series oĨ studies on ^an &rancisco͛s City Carshare ǁhere a ĮŌh surǀey ǁas conducted on
members and nonͲmembers in March 2005, Ĩour years aŌer the ƉroŐram ǁas launched͘
DetŚŽĚŽlŽŐLJ
This study conƟnued to emƉloy the same matchedͲƉair analyƟcal aƉƉroach in Zobert Cerǀero͛s ͞City Car^hare:
&irstͲzear Traǀel Demand ImƉacts͟ ǁith a samƉle oĨ 52ϳ members and 45 nonͲmembers͘
Results
While there ǁas no staƟsƟcal siŐniĮcant decline in sMT amonŐ members, ǁhen adũusted Ĩor mode (ǁalŬinŐ,
cyclinŐ, and transit are counted as njero since they add no neǁ ǀehicles) and occuƉancy (number oĨ occuƉants in a
motorinjed ǀehicle), staƟsƟcally siŐniĮcant declines oĨ ϲϳй ǁere recorded͘
There ǁas liƩle diīerence in the chanŐes in household ǀehicle oǁnershiƉ betǁeen members and nonͲmembers
thouŐh members ǁere less liŬely to increase oǁnershiƉ͘ This is due to the surǀey asŬinŐ members iĨ they had
ŐoƩen rid oĨ a car betǁeen 2003 and 2005, ǁhich is suŐŐesƟǀe that most oĨ the sheddinŐ occurred betǁeen 2001
and 2003 and subseƋuently leǀelled oī aŌer 2003͘ The study also includes ordinal loŐit model usinŐ data oǀer the
enƟre Ɖeriod (2001Ͳ2005) in ƉredicƟnŐ Įǀe ranŬͲordered chanŐes in household ǀehicle oǁnershiƉ: net reducƟon
oĨ tǁo or more cars͖ net reducƟon oĨ one car͖ no chanŐe͖ net increase oĨ one͖ or net increase oĨ tǁo or more͘ The
model Įnds that membershiƉ is associated ǁith net declines in ǀehicles oǁnershiƉ͘
ssessŵeŶt
MethodoloŐically, the City Car^hare studies are the stronŐest amonŐ the literature surǀeyed͘ The use oĨ matchedͲ
Ɖair analysis alloǁs a Őreater deŐree oĨ aƩribuƟon in behaǀioral chanŐes to the carͲsharinŐ as oƉƉosed to other
Ĩactors (e͘Ő͘ increasinŐ Ĩuel Ɖrices)͘ This is because these Ĩactors can be assumed to eīect members and nonͲ
members eƋually͘ Kne concern is that the sinje oĨ the nonͲmembers is small relaƟǀe to the member samƉle and
declines ǁith each iteraƟon oĨ the study͘ ThouŐh this is Ɖrobably due to City Car^hare edžƉansion oǀer the Įǀe years,
it introduces a deŐree oĨ uncertainty about the conclusions that the ƉaƉers draǁ͘
B O S T O N M AY O R ’ S O F F I C E
39
Car-Sharing and Public Parking in Boston
AƉƉendix &͗ PredicƟǀe Model on ChanŐes in sehicle KǁnershiƉ Ĩor City CarShare
In the Įnal installment oĨ the three ƉaƉer series on ^an &rancisco͛s City Car^hare,ϲϴ Cerǀero et al created a model usinŐ
ordinal loŐit esƟmates Ĩor ƉredicƟnŐ net chanŐes in ǀehicle oǁnershiƉ amonŐ surǀey resƉondents͘ The ĨolloǁinŐ ranŬ
orders ǁere used:
1͘ Eet decrease oĨ tǁo or more cars
2͘ Eet decrease oĨ one car
3͘ Eo net chanŐe
4͘ Eet increase oĨ one car
5͘ Eet increase oĨ tǁo or more cars
The results are in the table beloǁ:
ChdK&&S ΈEEd C,AE'E /E KtEEZS,/PΉ
ͲϮ or ŵore cars
Ͳ1 car
No change
+1 Car
>ocaƟon
City Car^hare Deŵber ;zes͗ 1͖ No͗ ϬͿ
Kǁns a transit pass ;zes͗ 1͖ No͗ ϬͿ
WKD ǁithin Ъ oĨ residence ;zes͗ 1͖ No͗ ϬͿ
,as children ;zes͗ 1͖ No͗ ϬͿ
ge ;yearsͿ
Drive to ǁork ;zes͗ 1͖ No͗ ϬͿ
^uŵŵary staƟsƟcs
^aŵple sinje
ZϮ
Dode ChiͲsƋuared ;WrobabilityͿ
CKE&&/C/EEd
ESd/MAdE
Ͳϳ.3Ϭ1
Ͳϰ.ϮϮϮ
ͲϬ.Ϯ6
3.6ϰϰ
SdAEAZ
EZZKZ
Ϭ.ϴ11
Ϭ.6ϳ6
Ϭ.63ϴ
Ϭ.953
ͲϬ.9ϳϴ
ͲϬ.ϰ1ϰ
ͲϬ.ϰ9ϳ
Ϭ.51ϰ
ͲϬ.ϬϮ9
Ϯ.ϳ65
Ϭ.ϰϬϮ
Ϭ.199
Ϭ.ϮϮ5
Ϭ.Ϯ9ϳ
Ϭ.Ϭ1
Ϭ.ϰϳ9
PZKA/L/dz
Ϭ
Ϭ
Ϭ.6ϴϰ
Ϭ
Ϭ.Ϭ15
Ϭ.Ϭ3ϴ
Ϭ.ϬϮϴ
Ϭ.Ϭϴϰ
Ϭ.ϬϬ3
Ϭ
53Ϭ
Ϭ.Ϭ69
61.ϰ5 ;Ϭ.ϬϬϬͿ
In an ordinal loŐit, there is a coeĸcient Ĩor each cutoī (i͘e͘ ranŬ order), ǁhich toŐether ǁith the other coeĸcients
is used to create a ǀalue (^) that is Ɖassed throuŐh the cumulaƟǀe loŐisƟc distribuƟon ĨuncƟon to Őet a cumulaƟǀe
Ɖrobability Ĩor that cutoī and the ones that are ranŬed beloǁ it͘
hsinŐ the ĨuncƟons aboǀe, the esƟmated Ɖrobability that a 31 year old, childless, transit Ɖass holder ǁho does not driǀe
to ǁorŬ, and has PKD close by ǁill Őiǀe uƉ 1 or more ǀehicles (the cumulaƟǀe Ɖrobability oĨ the Įrst tǁo ranŬs) is:
» 1ϵ͘25й Ĩor members
» ϴ͘23й Ĩor nonͲmembers
This means that a member oĨ CityCarshare (ǁith the aĨoremenƟoned characterisƟcs) ǁas 11 ƉercentaŐe Ɖoints more
liŬely to Őiǀe uƉ one or more ǀehicles (net) than a nonͲmember͘
6ϴ Cervero͕ 'olub͕ and Nee͕ ͞City Car^hare.͟
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B O S T O N M AY O R ’ S O F F I C E
Car-Sharing and Public Parking in Boston
AƉƉendix '͗ etermininŐ Moďility Scores
To calculate mobility scores, this reƉort adoƉted and modiĮed MaƩheǁ Danish͛s aƉƉroach͘ϲϵ hsinŐ the MT͛s
'eneral Transit &eed ^ƉeciĮcaƟon ('T&^) Įles and cells Mass'I^ Őrid ĨrameǁorŬ, each cell in oston ǁas Őiǀen a
mobility score as Ĩolloǁs:
1͘ &ind all ,ubǁay, bus, streetcar, and subǁay staƟons ǁithin ranŐe oĨ the center oĨ the cell͘ To be considered
ǁithin ranŐeϳ0
» a ,ubǁay staƟon ǁould need to be ǁithin 400 meters,
» a bus stoƉ ǁould need to also be 400 meters,
» a streetcar staƟon ǁould need to be ϴ00 meters,
» and a subǁay staƟon ǁould need to be ǁithin 1,000 meters͘
2͘ &or each oĨ these staƟons, determine their actual (straiŐht line) distance Ĩrom the center oĨ the cell as ǁell
as their ĨreƋuency oĨ serǀice (i͘e͘ hoǁ many Ɵmes does a bus or train stoƉ there on a Őiǀen ǁeeŬday)͘ &or
,ubǁay, the ĨreƋuency ǁas set at 10, the assumed aǀeraŐe number aǀailable biŬes͘
3͘ ^um the result oĨ ĨreƋuency diǀided by distance Ĩor all oĨ staƟons ǁithin ranŐe oĨ the cell to Őet the
mobility score Ĩor that cell͘
There are seǀeral caǀeats related to this aƉƉroach:
» stoƉ doesn͛t haǀe to be ǁithin oston city limits to be considered ǁithin ranŐe oĨ a cell͘
» The distances used Ĩor the ǁithin ranŐe determinaƟon as ǁell as the actual distance Ĩrom the center oĨ
a Őiǀen cell are straiŐht line distances͘ This means that they could ƉotenƟally understate the actual (i͘e͘
ǁalŬinŐ) distances to the staƟon͘
» esides beinŐ ƉriǀileŐed in terms oĨ acceƉtable distances, streetcar and subǁay staƟons enũoy an added
adǀantaŐe because their tǁoͲǁay nature (Inbound and Kutbound) eīecƟǀely doubles their ĨreƋuency͘
69 Danish͕ ͞džploring dransit and Driving ehavior in D͕ ǁith 'oogle &usion dables.͟
ϳϬ :arreƩ talker͕ ͞asics͗ talking Distance to dransit͕͟ ,uman dransit͕ pril Ϯϰ͕ ϮϬ11͕ hƩp͗ͬͬǁǁǁ.huŵantransit.orgͬϮϬ11ͬϬϰͬbasicsͲǁalkingͲdistanceͲtoͲtransit.
htŵl.
B O S T O N M AY O R ’ S O F F I C E
41
Car-Sharing and Public Parking in Boston
AƉƉendix ,͗ Study Protocol to Examine the /mƉacts oĨ Car-SharinŐ in oston
hnit oĨ analysis͗ ,ousehold
hnit oĨ randominjaƟon͗ 250mdž250m cell
ExƉlanatory ǀariaďle͗ Eumber oĨ shared cars added to the cell since the beŐinninŐ oĨ the study
Study uraƟon͗ Four years
Kutcome ǀariables (household leǀel)
» Eumber oĨ Ɖriǀate ǀehicles oǁned by the household as ǁell as their aƩributes (e͘Ő͘ year, maŬe, model, Ĩuel
eĸciency)
» ǀeraŐe daily ǀehicle miles traǀelled and ',' emissions
» Eumber oĨ C^K members
Data source(s)
» sehicle reŐistry and insƉecƟon records Ĩrom the MassachuseƩs ZeŐistry oĨ Motor sehicles (a diǀision oĨ the
MassachuseƩs DeƉartment oĨ TransƉortaƟon) ʹ this is the same data that the MassachuseƩs sehicle Census
ǁas able to access and use͘
» C^K MembershiƉ Data
» Census Data
^amƉlinŐ ^inje ^elecƟon
In order to detect a 0͘11 (or 11й) ǀehicle oǁnershiƉ reducƟonϳ1 ǁith a Ɖoǁer oĨ 0͘ϴ and a standard deǀiaƟon oĨ
1͘0ϲ5 ǀehicles, the study needs aƉƉrodžimately 1,500 households in each arm͘ This means a samƉle sinje oĨ 3,000
households is reƋuired͘ ased on the 2010 census, there are (on aǀeraŐe) 125 households in a cell͘ This means
aƉƉrodžimately 30 cells are reƋuired͘ ,oǁeǀer, Őiǀen the ƉotenƟal Ĩor conĨounders and the small sinje oĨ the eīect, a
larŐer samƉle oĨ ϴ0 cells is recommended͘
ZandominjaƟon Method
1͘ IdenƟĨy Ɖartner carͲsharinŐ orŐaninjaƟons (C^Ks) that are ǁillinŐ to ƉarƟciƉate in the study͘ n incenƟǀe
ǁould be to only allocate Ɖublic ƉarŬinŐ sƉaces throuŐhout the City oĨ oston to C^Ks that ƉarƟciƉate in this
study͘ ddiƟonal incenƟǀes such as discounƟnŐ the Ɖrice oĨ Ɖermits or allocaƟnŐ more Ɖublic ƉarŬinŐ sƉaces
can also be used͘
2͘ sŬ the Ɖartner C^Ks to choose ϴ0 cells (Ĩrom the 2,05ϳ 250mdž250m cells that coǀer oston͖ see FiŐure 13)
ǁhere they ǁould liŬe to Ɖlace at least Ĩour addiƟonal shared cars in Ɖublic ƉarŬinŐ sƉaces oǀer a tǁo year
Ɖeriod͘ ny cell can be chosen ǁith the condiƟon that there is a tǁoͲcell ŐaƉ betǁeen each oĨ the chosen
cells to Ɖreǀent crossoǀer eīects͘
3͘ ach cell is matched ǁith another cell that shares similar characterisƟcs͘ These matchinŐ characterisƟcs are:
a͘ PoƉulaƟon
b͘ Eumber oĨ C^K members
ϳ1 dhis is the reducƟon detected by Cervero et al in the Įnal installŵent oĨ their studies on City Car^hare.
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B O S T O N M AY O R ’ S O F F I C E
Car-Sharing and Public Parking in Boston
c͘ ǀeraŐe number oĨ ǀehicles Ɖer household
d͘ ǀeraŐe household income
4͘ From each Ɖair, one cell is chosen at random Ĩor assiŐnment to the treatment arm, the other is assiŐned to
the control arm͘
5͘ The ǀalues oĨ the outcome ǀariables aboǀe are recorded Ĩor all households in the study (i͘e͘ the ͞beĨore͟
ǀalue)͘
ϲ͘ The edžƉeriment beŐins ǁith the City oĨ oston allocaƟnŐ Ɖublic ƉarŬinŐ sƉaces to shared cars in the
treatment cells͘ This conƟnues as necessary Ĩor the study duraƟon͘ For the duraƟon oĨ the study:
» CSKs are not alloǁed to increase the numďer oĨ shared cars in Ɖriǀate or Ɖuďlic ƉarŬinŐ sƉaces in and tǁo
cells out ;i͘e͘ the͟ ďorder͟Ϳ Ĩrom cells in the control arm͘
» C^Ks are alloǁed to increase the number oĨ shared cars in both Ɖriǀate and Ɖublic ƉarŬinŐ sƉaces in and
around cells Ĩrom the treatment arm as lonŐ as the Ɖreǀious restricƟon is resƉected͘ The City oĨ oston
needs to be noƟĮed about cars added to Ɖriǀate ƉarŬinŐ sƉaces͘
Standard Errors
s the mechanism oĨ assiŐnment is at the cell leǀel, ǁhile the unit oĨ analysis is at the household leǀel, clustered
standard errors should be used in the analysis͘
MeasurinŐ the ImƉact
DŽĚelϭ;ŝīeƌeŶĐeͲŝŶͲĚŝīeƌeŶĐeͿ
For each household let:
» zh: Kutcome ǀariable
» Dh: The number oĨ shared cars in Ɖriǀate or Ɖublic ƉarŬinŐ sƉaces ǁithin 400 meters oĨ the household
» Th: dummy ǀariable that is set to 0 iĨ the obserǀaƟon ǁas beĨore the edžƉeriment started and 1 iĨ ǁas aŌer
the edžƉeriment started
The coeĸcient ɴ3 on the interacƟon term (Dh* Th) is the esƟmated causal eīect oĨ a one shared car increase on zh͘
B O S T O N M AY O R ’ S O F F I C E
43
Car-Sharing and Public Parking in Boston
FIGURE 13: 250MX250M CELLS FOR BOSTON
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B O S T O N M AY O R ’ S O F F I C E