2. Shared Mobility Models and Their Impact on Sustainability
2.1. Impacts on Sustainability
2.1.1. Market Size
2.1.2. Car Ownership, Distance Travelled, CO2 Emissions, and Congestion
3. Incentives to Encourage Shared Mobility
- Short term rental of shared vehicles (Model 2 above, where vehicles are managed and owned by a provider) is “not considered an attractive substitute for private-vehicle ownership, because it is rarely appropriate for a daily commute”  (p. 105). Even young people may express enthusiasm over the idea of Model 2, but show reluctance to actually use it , and most aspire and plan to buy a car . 67% of U.S. respondents to a survey preferred “driving their own cars over using ride-hailing apps” (Model 3 above, where companies own no cars themselves, but they sign up ordinary car owners who act as drivers), and 63% would not give up their vehicles for these types of rides, even if they were free . Given the above, it will not be easy to convince consumers to switch to shared mobility services, especially those that entail simultaneously sharing a vehicle with strangers (Model 4) and compromising, even slightly, on departure and arrival times and travel duration.
- Basic transport economics defines the generalised cost of a trip as the monetary cost or out-of-pocket expenditure, plus the time taken to complete the trip, times the value of time of the trip maker. Trip makers are assumed to be rational and to minimise their generalised cost of travel. The value of time varies according to a number of factors , with the most important one being income. In addition, it has long been recognised that business (working) travel time values are different from non-working travel time ones, which include commuting, and also travel for other purposes [61,62]. The estimates of the value of travel time during the course of work are typically three to five times higher than those for other purposes, and traditionally, travel time during working hours has been valued at the wage rate, although this practice has been recently challenged .
- To complicate things further, there are many other factors that influence mode choice, such as reliability, convenience, and comfort, to name a few. Reliability has lately been incorporated in the generalised cost of travel  (p. 32), . Convenience is difficult to define and value but there have been attempts to model it for public transport . Comfort is related to crowding and it can be taken into account by using value of travel time multipliers for different modes of public transport . These multipliers can take a range of values according to whether there are plenty of seats free and the passenger does not have to sit next to anyone, or there are no seats free, and the bus or train is densely packed, or situations in-between . Evidence shows that the passengers, even those who regularly travel by bus, prefer to be in a relatively empty vehicle and not have to seat next to anyone else . Convincing solo car drivers to share taxis or mini-buses may therefore be challenging, and will need strong financial incentives to compensate for the disutility caused by the reduction in comfort.
- Last but not least, waiting time, for example, at bus stops or train stations, has a higher weight, mainly as a result of impatience. This has a long tradition and recent research provides fresh evidence for this to be the case, with waiting time multipliers being over 2 and even 3, depending on transport mode and trip purpose .
- Command-and-control measures, such as the closure of certain roads or areas to privately owned and driven vehicles;
- Subsidies to compensate for the disutility of waiting, taking longer to travel, and/or sharing the vehicle with other passengers;
- Charges, such as congestion charges during peak times or simply charges for (the privilege of) using roads; and
- Incentives in-kind, such as use of dedicated bus lanes for shared mobility vehicles
4. Research Needs
Conflicts of Interest
- Rabbitt, N.; Ghosh, B. Economic and environmental impacts of organised Car Sharing Services: A case study of Ireland. Res. Transp. Econ. 2016, 57, 3–12. [Google Scholar] [CrossRef]
- Taylor, B.; Chin, R.; Crotty, M.; Dill, J.; Hoel, L.; Manville, M.; Polzin, S.; Schaller, B.; Shaheen, S.; Sperling, D.; et al. Between Public and Private Mobility: Examining the Rise of Technology-Enabled Transportation Services; Special Report 319; Committee for Review of Innovative Urban Mobility Services, Transportation Research Board, The National Academy of Sciences: Washington, DC, USA, 2016; Available online: http://nap.edu/21875 (accessed on 19 October 2017).
- Shaheen, S.; Chan, N.; Micheaux, H. One-way carsharing’s evolution and operator perspectives from the Americas. Transportation 2015, 42, 519–536. [Google Scholar] [CrossRef]
- Martin, E.W.; Shaheen, S.A. Greenhouse Gas Emission Impacts of Carsharing in North America. IEEE Trans. Intell. Transp. Syst. 2011, 12, 1074–1086. [Google Scholar][Green Version]
- Viegas, J.; Martinez, L. Transition to Shared Mobility: How large Cities Can Deliver Inclusive Transport Services; Corporate Partnership Board Report; International Transport Forum: Paris, France, 2017; Available online: https://www.itf-oecd.org/sites/default/files/docs/transition-shared-mobility.pdf (accessed on 18 October 2017).
- Andwari, A.M.; Pesiridis, A.; Rajoo, S.; Martinez-Botas, R.; Esfahanian, V. A review of Battery Electric Vehicle technology and readiness levels. Renew. Sustain. Energy Rev. 2017, 78, 414–430. [Google Scholar] [CrossRef]
- Hao, H.; Cheng, X.; Liu, Z.; Fuquan, Z. Electric vehicles for greenhouse gas reduction in China: A cost effectiveness analysis. Transp. Res. D Transp. Environ. 2017, 56, 68–84. [Google Scholar] [CrossRef]
- Newbery, D.; Strbac, G. What is needed for battery electric vehicles to become socially cost competitive? Econ. Transp. 2016, 5, 1–11. [Google Scholar] [CrossRef][Green Version]
- Figenbaum, E. Perspectives on Norway’s supercharged electric vehicle policy. Environ. Innov. Soc. Transit. 2017, 25, 14–34. [Google Scholar] [CrossRef]
- Langbroek, J.; Franklin, J.; Susilo, Y. The effect of policy incentives on electric vehicle adoption. Energy Policy 2016, 94, 94–103. [Google Scholar] [CrossRef]
- Bjerkan, K.Y.; Nørbech, T.E.; Nordtømme, M.E. Incentives for promoting Battery Electric Vehicle (BEV) adoption in Norway. Transp. Res. D Transp. Environ. 2016, 43, 169–180. [Google Scholar] [CrossRef]
- Lieven, T. Policy measures to promote electric mobility—A global perspective. Transp. Res. A Policy Pract. 2015, 82, 78–93. [Google Scholar] [CrossRef]
- Sierzchula, W.; Bakker, S.; Maat, K.; van Wee, B. The influence of financial incentives and other socio-economic factors on electric vehicle adoption. Energy Policy 2014, 68, 183–194. [Google Scholar] [CrossRef]
- Coffman, M.; Bernstein, P.; Wee, S. Electric vehicles revisited: A review of factors that affect adoption. Transp. Rev. 2017, 37, 79–93. [Google Scholar] [CrossRef]
- Egbue, O.; Long, S.; Samaranayake, V.A. Mass deployment of sustainable transportation: Evaluation of factors that influence electric vehicle adoption. Clean Technol. Environ. Policy 2017, 19, 1927–1939. [Google Scholar] [CrossRef]
- Heidrich, O.; Hil, G.A.; Neaimeh, M.; Huebner, Y.; Blythe, P.T.; Dawson, R.J. How do cities support electric vehicles and what difference does it make? Technol. Forecast. Soc. Chang. 2017, 123, 17–23. [Google Scholar] [CrossRef]
- Wang, N.; Pan, H.; Zheng, W. Assessment of the incentives on electric vehicle promotion in China. Transp. Res. A Policy Pract. 2017, 101, 177–189. [Google Scholar] [CrossRef]
- Mersky, A.C.; Sprei, F.; Samaras, C.; Qian, Z. Effectiveness of incentives on electric vehicle adoption in Norway. Transp. Res. D Transp. Environ. 2016, 46, 56–68. [Google Scholar] [CrossRef][Green Version]
- Zhang, X.; Wang, K.; Hao, Y.; Fan, J.-L.; Wei, Y.-M. The impact of government policy on preference for NEVs: The evidence from China. Energy Policy 2013, 61, 382–393. [Google Scholar] [CrossRef]
- Miramontes, M.; Pfertner, M.; Rayaprolu, H.; Schreiner, M.; Wulfhorst, G. Impacts of a multimodal mobility service on travel behavior and preferences: User insights from Munich’s first Mobility Station. Transportation 2017, 44, 1325–1342. [Google Scholar] [CrossRef]
- Schwieterman, J.; Bieszczat, A. The cost to carshare: A review of the changing prices and taxation levels for carsharing in the United States 2011–2016. Transp. Policy 2017, 57, 1–9. [Google Scholar] [CrossRef]
- Tyndall, J. Where no cars go: Free-floating carshare and inequality of access. Int. J. Sustain. Transp. 2017, 11, 433–442. [Google Scholar] [CrossRef]
- Ciari, F.; Balac, M.; Balmer, M. Modelling the effect of different pricing schemes on freefloating carsharing travel demand: A test case for Zurich. Transportation 2015, 42, 413–433. [Google Scholar] [CrossRef]
- Nijland, H.; van Meerkerk, J. Mobility and environmental impacts of car sharing in the Netherlands. Environ. Innov. Soc. Transit. 2017, 23, 84–91. [Google Scholar] [CrossRef]
- Becker, H.; Ciari, F.; Axhausen, K.W. Modeling free-floating car-sharing use in Switzerland: A spatial regression and conditional logit approach. Transp. Res. C Emerg. Technol. 2017, 81, 286–299. [Google Scholar] [CrossRef][Green Version]
- Kim, J.; Rasouli, S.; Timmermans, H.J.P. The effects of activity-travel context and individual attitudes on car-sharing decisions under travel time uncertainty: A hybrid choice modeling approach. Transp. Res. D Transp. Environ. 2017, 56, 189–202. [Google Scholar] [CrossRef]
- Kopp, J.; Gerike, R.; Axhausen, K. Do sharing people behave differently? An empirical evaluation of the distinctive mobility patterns of free-floating car-sharing members. Transportation 2015, 42, 449–469. [Google Scholar] [CrossRef]
- Nourinejad, M.; Roorda, M. Carsharing operations policies: A comparison between one-way and two-way systems. Transportation 2015, 42, 497–518. [Google Scholar] [CrossRef]
- Bicocchi, N.; Mamei, M. Investigating ride sharing opportunities through mobility data analysis. Pervasive Mob. Comput. 2014, 14, 83–94. [Google Scholar] [CrossRef]
- Bongiovanni, C.; Kaspi, M.; Geroliminis, N. The Electric Autonomous Dial-a-Ride Problem. In Proceedings of the 17th Swiss Transport Research Conference, Monte Verità, Ascona, 17–19 May 2017; Available online: https://verolog2017.sciencesconf.org/140001/document (accessed on 23 October 2017).
- Hara, Y.; Hato, E. A car sharing auction with temporal-spatial OD connection conditions. Transp. Res. Procedia 2017, 23, 22–40. [Google Scholar] [CrossRef]
- Morency, C.; Verreault, H.; Demers, M. Identification of the minimum size of the shared-car fleet required to satisfy car-driving trips in Montreal. Transportation 2015, 42, 435–447. [Google Scholar] [CrossRef]
- Mallus, M.; Colistra, G.; Atzori, L.; Murroni, M.; Pilloni, V. Dynamic Carpooling in Urban Areas: Design and Experimentation with a Multi-Objective Route Matching Algorithm. Sustainability 2017, 9, 254. [Google Scholar] [CrossRef]
- Becker, H.; Loder, A.; Schmid, B.; Axhausen, K.W. Modeling car-sharing membership as a mobility tool: A multivariate Probit approach with latent variables. Travel Behav. Soc. 2017, 8, 26–36. [Google Scholar] [CrossRef][Green Version]
- Paundra, J.; Rook, L.; van Dalen, J.; Ketter, W. Preferences for car sharing services: Effects of instrumental attributes and psychological ownership. J. Environ. Psychol. 2017, 53, 121–130. [Google Scholar] [CrossRef]
- Prieto, M.; Baltas, G.; Stan, V. Car sharing adoption intention in urban areas: What are the key sociodemographic drivers? Transp. Res. A Policy Pract. 2017, 101, 218–227. [Google Scholar] [CrossRef]
- Rinzivillo, S.; Pedreschi, D.; Giannotti, F. Never drive alone: Boosting car pooling with network analysis. Inf. Syst. 2017, 64, 237–257. [Google Scholar]
- Juschten, M.; Ohnmacht, T.; Thao, V.T.; Gerike, R.; Hössinger, R. Carsharing in Switzerland: Identifying new markets by predicting membership based on data on supply and demand. Transportation 2017, 1–24. [Google Scholar] [CrossRef]
- Angrist, J.D.; Caldwell, S.; Hall, J.V. Uber vs. Taxi: A Driver’s Eye View. National Bureau of Economic Research Working Paper 23891. 2017. Available online: http://www.nber.org/papers/w23891 (accessed on 20 August 2018).
- Einav, L.; Farronato, C.; Levin, J. Peer-to-Peer Markets. National Bureau of Economic Research Working Paper 21496. 2015. Available online: http://www.nber.org/papers/w21496 (accessed on 20 August 2018).
- Wallsten, S. The Competitive Effects of the Sharing Economy: How is Uber Changing Taxis? Technology Policy Institute: Washington, DC, USA, 2015; Available online: https://techpolicyinstitute.org/wp-content/uploads/2015/06/the-competitive-effects-of-the-2007713.pdf (accessed on 20 August 2018).
- Bieszczat, A.; Schwieterman, J. Carsharing: Review of its public benefits and level of taxation. Transp. Res. Rec. J. Transp. Res. Board 2012, 2319, 105–112. [Google Scholar] [CrossRef]
- Corciolani, M.; Borghini, S. Buying, renting, and sharing: Investigating new forms of acquisition. Mercati Competitività 2018, 1, 15–20. [Google Scholar] [CrossRef]
- Ballús-Armet, I.; Shaheen, S.A.; Clonts, K.; Weinzimmer, D. Peer-to-Peer Carsharing Exploring Public Perception and Market Characteristics in the San Francisco Bay Area, California. Transp. Res. Rec. J. Transp. Res. Board 2014, 2416, 27–36. [Google Scholar] [CrossRef]
- Barrios, J.A.; Doig-Godier, J. Fleet Sizing for Flexible Carsharing Systems Simulation-Based Approach. Transp. Res. Rec. J. Transp. Res. Board 2014, 2416, 1–9. [Google Scholar] [CrossRef]
- Bardhi, F.; Eckhardt, G.M. Access-Based Consumption: The Case of Car Sharing. J. Consum. Res. 2017, 39, 881–898. [Google Scholar] [CrossRef]
- Schaefers, T.; Lawson, S.; Kukar-Kinney, M. How the burdens of ownership promote consumer usage of access-based services. Mark. Lett. 2015, 27, 569–577. [Google Scholar] [CrossRef]
- Shaheen, S.; Sperling, D.; Wagner, C. Carsharing in Europe and North America: Past, Present, and Future. Transp. Q. 1998, 52, 35–52. [Google Scholar]
- Enoch, M.; Taylor, J. A worldwide review of support mechanisms for car clubs. Transp. Policy 2006, 13, 434–444. [Google Scholar] [CrossRef][Green Version]
- Transport for London Website. Apply for a Taxi Driver Licence. Available online: https://tfl.gov.uk/info-for/taxis-and-private-hire/licensing/apply-for-a-taxi-driver-licence (accessed on 21 August 2018).
- Finger, M.; Bert, N.; Kupfer, D.; Montero, J.; Wolek, M. Research for the TRAN Committee—Infrastructure Funding Challenges in the Sharing Economy, Transport Area of the Florence School of Regulation (FSR Transport) at the European University Institute (EUI). Report prepared for the European Parliament’s Committee on Transport and Tourism, Directorate-General for Internal Policies; Policy Department for Structural and Cohesion Policies, Transport and Tourism. 2017. Available online: http://www.europarl.europa.eu/RegData/etudes/STUD/2017/601970/IPOL_STU(2017)601970_EN.pdf (accessed on 25 October 2017).
- Grosse-Ophoff, A.; Hausler, S.; Heineke, K.; Möller, T. How Shared Mobility Will Change the Automotive Industry. McKinsey & Company. 2017. Available online: https://www.mckinsey.com/industries/automotive-and-assembly/our-insights/how-shared-mobility-will-change-the-automotive-industry (accessed on 18 October 2017).
- World Bank Webpage. Countries and Economics. Available online: https://data.worldbank.org/country/ (accessed on 1 November 2017).
- Schreier, H.; Becker, U.; Heller, J.; Team Red Deutschland GmbH. Evaluation CarSharing (EVA-CS); Landeshauptstadt München; Team Red Deutschland GmbH: Berlin, Germany, 2015. [Google Scholar]
- Furtado, F.; Martinez, L.; Petrik, O. Shared Mobility Simulations for Helsinki; International Transport Forum: Paris, France, 2017; Available online: https://www.itf-oecd.org/shared-mobility-simulations-helsinki (accessed on 26 October 2017).
- Fischer, B. In Uber vs. Taxi Cab Fight, Expense Reports Offer Telling Barometer. N. Y. Bus. J. 2015. Available online: https://www.bizjournals.com/newyork/blog/techflash/2015/04/uber-taxi-expense-report-certify-study.html (accessed on 1 November 2017).
- Kim, K.; Baek, C.; Lee, J.-D. Creative destruction of the sharing economy in action: The case of Uber. Transp. Res. A Policy Pract. 2018, 110, 118–127. [Google Scholar] [CrossRef]
- Transport for London. Travel in London. Report 10. 2017. Available online: http://content.tfl.gov.uk/travel-in-london-report-10.pdf (accessed on 15 August 2018).
- Magnani, G.; Bertolotti, T.; Zucchella, A. Cognitive aspects of car sharing in Millennials. Active sharers and reluctant users. Mercati Competitività 2018, 1, 39–62. [Google Scholar] [CrossRef]
- Giffi, C.A.; Vitale, J.; Rodriguez, M.D.; Gangula, B.; Schmith, S. The Changing Nature of Mobility. Deloitte Review Issue 15. 2014. Available online: https://www2.deloitte.com/insights/us/en/deloitte-review/issue-15/automotive-trends-gen-y.html (accessed on 16 August 2018).
- Mackie, P.; Wardman, M.; Fowkes, A.; Whelan, G.; Nellthorp, J.; Bates, J. Values of Travel Time Savings in the UK—Full Report; Report to the UK Department for Transport; Institute for Transport Studies, University of Leeds: Leeds, UK, 2003; Available online: http://eprints.whiterose.ac.uk/2079/2/Value_of_travel_time_savings_in_the_UK_protected.pdf (accessed on 25 October 2017).
- Wardman, M.; Batley, R.; Laird, J.; Mackie, P.; Bates, J. How should business travel time savings be valued? Econ. Transp. 2015, 4, 200–214. [Google Scholar] [CrossRef][Green Version]
- Small, K.; Verhoef, E. Economics of Urban. Transportation; Routledge: London, UK, 2007. [Google Scholar]
- Arup; Institute for Transport Studies (ITS); University of Leeds (and Affiliates); Accent. Provision of Market Research for Value of Travel Time Savings and Reliability. Report Prepared for the UK Department for Transport. 2015. Available online: https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/470231/vtts-phase-2-report-issue-august-2015.pdf (accessed on 25 October 2017).
- International Transport Forum. Valuing Convenience in Public Transport; Roundtable Report 156; Organisation for Economic Co-operation and Development: Paris, France, 2014; Available online: http://www.oecd.org/publications/valuing-convenience-in-public-transport-9789282107683-en.htm (accessed on 17 October 2017).
- Eskeland, G.; Feyzioglu, T. Rationing Can Backfire: The ‘Day without a Car’ in Mexico City. World Bank Econ. Rev. 1997, 11, 383–408. [Google Scholar] [CrossRef]
- Baumol, W.; Oates, W. The Theory of Environmental Policy, 2nd ed.; Cambridge University Press: Cambridge, UK, 1988. [Google Scholar]
- Hepburn, C. Regulation by prices, quantities, or both: A review of instrument choice. Oxf. Rev. Econ. Policy 2006, 22, 226–247. [Google Scholar] [CrossRef]
- Santos, G.; Behrendt, H.; Maconi, L.; Shirvani, T.; Teytelboym, A. Externalities and Economic Policies in Road Transport. Res. Transp. Econ. 2010, 28, 2–45. [Google Scholar] [CrossRef]
- Verhoef, E.T.; Nijkamp, P.; Rietveld, P. Tradeable permits: Their potential in the regulation of road transport externalities. Environ. Plan. B Plan. Des. 1997, 24, 527–548. [Google Scholar] [CrossRef]
- Raux, C. The use of transferable permits in Transport Policy. Transp. Res. D Transp. Environ. 2004, 9, 185–197. [Google Scholar] [CrossRef]
- Albrecht, J. Tradable CO2 permits for cars and trucks. J. Clean. Prod. 2001, 9, 179–189. [Google Scholar] [CrossRef]
- Raux, C.; Marlot, G. A system of tradable CO2 permits applied to fuel consumption by motorists. Transp. Policy 2005, 12, 255–265. [Google Scholar] [CrossRef]
- Wadud, Z.; Noland, R.; Graham, D. Equity analysis of personal tradable carbon permits for the road transport sector. Environ. Sci. Policy 2008, 11, 533–544. [Google Scholar] [CrossRef]
- Hahn, R.; Hester, G. Marketable Permits: Lessons for Theory and Practice. Ecol. Law Q. 1989, 361, 361–406. [Google Scholar]
- Hansjürgens, B. The US approach to pollution control: Lessons for climate policy. In Emissions Trading for Climate Policy: US and European Perspectives; Hansjürgens, B., Ed.; Cambridge University Press: Cambridge, UK, 2005; pp. 61–62. [Google Scholar]
- European Commission Webpage. EU Emissions Trading System (EU ETS). Available online: https://ec.europa.eu/clima/policies/ets_en (accessed on 26 October 2017).
- Vaughan, R.; Daverio, R. Assessing the Size and Presence of the Collaborative Economy in Europe. Document Prepared for the European Commission (DG GROW). 2016. Available online: https://publications.europa.eu/en/publication-detail/-/publication/2acb7619-b544-11e7-837e-01aa75ed71a1/language-en (accessed on 1 November 2017).
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