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Technological Enhancements to Improve and Expand Casual Carpooling Systems


Traditional carpooling declined in the United States from a 20% mode share in 1980 to 13% in 1990, and then to 10% in 2004, after which it has remained stable at this low level. A variation on the traditional carpool, casual carpooling, occurs in three U.S. metropolitan areas (Washington, D.C., San Francisco, and Houston) and may be an important strategy to help reverse this downward trend. While both casual carpooling and traditional carpooling entail sharing rides, casual carpooling enables participants to ride with different people for each trip with no ongoing commitments, and rideshare arrangements can be made instantaneously. Casual carpooling matches drivers and riders based on the three most basic variables of mobility: origin, destination, and time of departure. Drivers and riders meet at pre-arranged locations, such as park-and-ride lots near the entrance to high-occupancy vehicle (HOV) lanes, create carpools on the fly based on shared destinations, and then have no continuing obligations once the trip has ended. Casual carpooling provides the same benefits as traditional carpooling without a number of its most commonly cited limitations or drawbacks, such as related to scheduling and forging commitments.

While, as noted above, casual carpooling is clearly advantageous to its users and to transportation system efficiency overall, its benefits are limited because in most U.S. metropolitan areas and in most travel corridors, the conditions for successful casual carpooling do not exist. The necessary conditions include: HOV lanes that offer substantial time savings and require at least three people per vehicle (providing “safety in numbers” that would not exist if only two strangers are paired in a car); sufficient parking at the morning departure location; and back-up transit service for riders if a casual carpooling ride does not materialize. The absence of even one of these conditions precludes casual carpooling from getting started.

At the end of 2010, FHWA conducted a scan tour of the three metropolitan areas with existing casual carpooling systems in the U.S. (see: Follow-up focus groups were conducted in each city in mid-2012 (see: While a clear finding of the tour and focus groups was that casual carpoolers give their systems high grades and are skeptical of proposed major changes, many nevertheless expressed receptivity to targeted system enhancements that address specific limitations of the existing systems. Because the substantial social and practical barriers to casual carpooling have been overcome in the three metropolitan areas that were visited on the scan tour, and such barriers may not easily be overcome in metropolitan areas where casual carpooling does not yet exist, this topic is targeted to support research focused on any of the three U.S. metropolitan areas that have casual carpooling, but in a corridor or at a specific location that have a majority—but not all—of the preexisting conditions shown to enable casual carpooling (and thus where casual carpooling isn’t working well or at all). Applicants need to describe one or more barriers in a specific corridor or at a specific location in one of the three metropolitan areas that is either limiting the amount of casual carpooling occurring or is responsible for casual carpooling not occurring at all in the named corridor or location, and then describe the approach(es) that will be taken, including the institutional support to be solicited or offered, if any, to overcome the barrier(s).

Research published summarizing lessons learned from FHWA’s scan tour ( identified these possible system enhancements that could address barriers to casual carpooling:

  • Early-arriving park-and-ride passengers may be incentivized to park further from carpool pick-up points, thereby freeing up closer-in parking for other riders who arrive later.
  • Some passengers would be willing to leave their cars at home entirely—eliminating the high emissions associated with cold-starts (prior to the catalytic converter warming), the need for parking, and a household requirement for an extra vehicle—in exchange for a close-to-home pick-up (perhaps taking transit back home or getting picked up by a family member at a nearby park-and-ride lot in the evening).
  • In Houston where casual carpooling works well for the morning commute to get into the city, but not in the reverse direction, and in Washington, D.C., and San Francisco where getting an afternoon lift back to some morning pick-up points is challenging, passengers would be willing to pay drivers for a reliable return trip, so long as the price is low enough to seem like a bargain as compared to other options.
  • For locations with casual carpooling participation levels that are a bit shy of what is needed for a reliable return trip, an online system enhancement could be created, where drivers and passengers can efficiently arrange matches electronically, in or close to realtime, using incentives to get this started.
  • Some drivers would agree to delay their return trips to near the time that the HOV restrictions are ending (and, hence, when riders are most in jeopardy of being stranded) in exchange for incentives.
  • At pick-up points where riders typically need to wait for drivers, but not vice versa, some drivers would be willing to take more passengers than needed to meet minimum HOV requirements in exchange for small incentives.
  • By enhancing security, new casual carpooling could be successfully launched to serve congested HOV-2 facilities, such as: through an app that requires drivers and passengers to verify their identities and records shared trips that take place; through an alternative system where drivers and passengers undergo background checks (or have their employers confirm where they work) and carry proof that they underwent such checks, or; through the use of webcams at pick-up point where video recordings of license plate numbers and driver and rider faces are made (but kept for only a short period of time, such as for one week unless a safety/security issue has been reported).
  • Passengers and riders would be willing to pay, or redeem credits earned through system supporting activities, to occasionally bypass a queue, at times when the passenger or vehicle lines are long and the participant is particularly time pressed, and where the driver and rider meet very nearby to (e.g., 100 yards away from), but not at, the queue (to avoid conflicts with other casual carpoolers).

This list represents only a subset of a vast array of potential applications that could be pursued to advance the general objective of applying effective strategies to create new casual carpooling options and grow related systems so that in the not-too-distant future they could cause a meaningful impact on travel and reduce congestion.

SBIR welcomes creative approaches to addressing the general objective noted in this topic and specific related challenges identified in research or by the applicant. (In the case of the latter, the applicant should specify the challenges being addressed and offer some evidence of their significance prior to presenting proposed solutions.)

Regardless of the challenges that the applicant chooses to address and the specific approaches selected to address them, it should be a design goal of any new system to inculcate a culture whereby drivers, especially, check for incentives daily to slightly modify their trips in ways that improve the system.

Applicants should explain why what they are proposing is likely to succeed, specifically discussing the elements of successful casual carpooling systems that inform their research. Applicants, or applicant teams, are being sought with both high levels of technical expertise and a demonstration of a deep appreciation for the practical and social factors that are important to casual carpooling participants or prospective participants. Applicants must demonstrate that, to the extent that the development of new prototype technologies is proposed, they have the capabilities (either directly or through venders) to successfully complete the required work.



Expected Phase I Outcomes

The outcome expected from Phase I is a detailed concept that demonstrates the viability of one or more tools and/or approaches to catalyze casual carpooling in a corridor or at a particular location within a corridor where it does not exist, or to make it work better in a corridor or at particular location within a corridor where, while occurring, is somehow under performing its potential.


Expected Phase II Outcomes

The expected Phase II outcome is a demonstration of a working prototype of one or more tools and/or approaches that catalyze casual carpooling in a corridor or at a particular location within a corridor where it does not exist, or to make it work better in a corridor or at particular location within a corridor where, while occurring, is somehow under performing its potential. The working prototype should be designed to collect usage metrics so that its effectiveness can be discerned in the location(s) that it is tested, and also to help inform the targeting of locations and overall expansion of future deployments.

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