Carpool & rideshare programs
Carpool and rideshare programs help commuters share transportation. Carpools and rideshares can be informal arrangements between individuals or be formally arranged through dynamic ridesharing programs or other ride-matching services.
Expected Beneficial Outcomes (Rated)
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Reduced emissions
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Reduced traffic congestion
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Reduced vehicle miles traveled
Other Potential Beneficial Outcomes
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Increased mobility
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Improved quality of life
Evidence of Effectiveness
Carpooling and ridesharing programs are suggested strategies to decrease emissions, reduce traffic congestion, and reduce vehicle miles traveled (VMT) (Wilson 2008, UC Davis-Yura 2006, ICF Consulting 2006, RAND-Sorenson 2008). Studies suggest that these programs can be cost effective (ICF Consulting 2006, RAND-Sorenson 2008, Gallivan 2011), especially for longer commutes (Silva-Send 2013); programs may also improve mobility and quality of life for seniors (Silvis 2009). Overall, transit incentives can increase use of alternative transportation; however, additional evidence is needed to confirm effects and costs of carpool and rideshare programs specifically (Graham-Rowe 2011).
Available research suggests that improving awareness, trust and willingness to ride with strangers, and flexibility in scheduling may increase carpool use (Chaube 2010, Deakin 2010, Levofsky 2001). Incentives such as free or decreased toll rates (UC Davis-Yura 2006, Li 2007, RAND-Sorenson 2008) and reduced parking prices for carpool or rideshare vehicles may also increase use (Salon 2012, Wilson 2008). High occupancy vehicle lanes (HOVs) may increase carpooling and ridesharing in some circumstances; local context strongly influences the success or failure of HOVs as well as other carpool or rideshare programs (Shewmake 2012).
Impact on Disparities
No impact on disparities likely
Implementation Examples
There are roughly 613 ride-matching services in the US and Canada. Many incorporate the use of technology (i.e., internet, mobile phones, and social networking) into rideshare services (Chan 2012). Several rideshare services are available in all or most of the 50 states and offer searchable databases to find carpool and rideshare opportunities (eRideShare, Gishigo, Ridester). In the 2009 National Transit Database, 27 states reported vanpool operations (Deitrick 2010).
Implementation Resources
CCAP-Transportation emissions - Center for Clean Air Policy (CCAP). CCAP Transportation emissions guidebook.
Citations - Evidence
* Journal subscription may be required for access.
RAND-Sorenson 2008 - Sorenson P, Wachs M, Min EY, et al. Moving Los Angeles: Short-term policy options for improving transportation. Santa Monica: RAND Corporation; 2008: Monograph Report 748.
ICF Consulting 2006 - ICF Consulting. Performance review of transportation fund for clean air projects: Literature review. Fairfax: ICF Consulting; 2006.
Chaube 2010* - Chaube V, Kavanaugh AL, Pérez-Quiñones MA. Leveraging social networks to embed trust in rideshare programs. In: Proceedings of the 43rd Hawaii International Conference on System Sciences - 2010. Washington, DC: Institute of Electrical and Electronics Engineers (IEEE); 2010.
Deakin 2010* - Deakin E, Frick KT, Shively KM. Markets for dynamic ridesharing? Case of Berkeley, California. Transportation Research Record: Journal of the Transportation Research Board. 2010;2187:131-7.
Levofsky 2001 - Levofsky A, Greenberg A. Organized dynamic ride sharing: The potential environmental benefits and the opportunity for advancing the concept. Washington, DC: Transportation Research Board 2001 Annual Meeting. 2001: Working Paper 01-0577.
Li 2007* - Li J, Embry P, Mattingly SP, et al. Who chooses to carpool and why? Examination of Texas carpoolers. Transportation Research Record: Journal of the Transportation Research Board. 2007;2021:110-7.
Wilson 2008* - Wilson RW, Brown KD. Carbon neutrality at the local level: Achievable goal or fantasy? Journal of the American Planning Association. 2008;74(4):497-504.
UC Davis-Yura 2006 - Yura EA, Eisinger D, Deb Niemeier. A review of on-road vehicle mitigation measures. Davis: University of California, Davis; 2006.
Silvis 2009 - Silvis J, Niemeier D. Social network and dwelling characteristics that influence ridesharing behavior of seniors. Transportation Research Record: Journal of the Transportation Research Board. 2009;(2118):47-54.
Salon 2012* - Salon D, Boarnet MG, Handy S, Spears S, Tal G. How do local actions affect VMT? A critical review of the empirical evidence. Transportation Research Part D: Transport and Environment. 2012;17(7):495–508.
Graham-Rowe 2011* - Graham-Rowe E, Skippon S, Gardner B, Abraham C. Can we reduce car use and, if so, how? A review of available evidence. Transportation Research Part A: Policy and Practice. 2011;45(5):401–18.
Gallivan 2011* - Gallivan F, Ang-Olson J, Liban CB, Kusumoto A. Cost-effective approaches to reduce greenhouse gas emissions through public transportation in Los Angeles, California. Transportation Research Record: Journal of the Transportation Research Board. 2011;2(2217):19–29.
Silva-Send 2013* - Silva-Send N, Anders S, Narwold A. Cost effectiveness comparison of certain transportation measures to mitigate greenhouse gas emissions in San Diego County, California. Energy Policy. 2013;62:1428–33.
Shewmake 2012* - Shewmake S. Can carpooling clear the road and clean the air?: Evidence from the literature on the impact of HOV lanes on VMT and air pollution. Journal of Planning Literature. 2012;27(4):363–74.
Citations - Implementation Examples
* Journal subscription may be required for access.
Chan 2012* - Chan ND, Shaheen SA. Ridesharing in North America: Past, present, and future. Transport Reviews: A Transnational Transdisciplinary Journal. 2012;32(1):93-112.
Ridester - Ridester. Life is journey. Share it.
Gishigo - GishiGo. Ride share network.
eRideShare - eRideShare.com.
Deitrick 2010 - Deitrick S, Briem CP, Beach S, Fan X. Project title: Impacts of vanpooling in Pennsylvania and future opportunities. Harrisburg: Pennsylvania Department of Transportation (PennDOT); 2010.