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|Federal Highway Administration > Publications > Public Roads > Vol. 77 · No. 2 > Fill Those Empty Seats!|
Publication Number: FHWA-HRT-13-006
Fill Those Empty Seats!
by Marc Oliphant, Allen Greenberg, Ron Boenau, and Jeremy Raw
Could dynamic ridesharing help combat traffic congestion in your metropolitan area?
Empty seats in private vehicles might be the greatest untapped transportation opportunity in the United States. Average vehicle occupancy across the country is less than two persons per vehicle, while the vast majority of private vehicles have the capacity to carry four or more passengers comfortably.
Low occupancy levels happen despite the fact that many of these car trips occur at about the same time (peak hours) and have similar destinations. The excessive number of vehicles on roadways causes a host of negative externalities such as traffic congestion, greenhouse gas emissions, and lost productivity due to traffic-related delays.
The obvious solution? Find ways to fill those empty seats. Historically, the Federal Government has promoted ridesharing mostly in times of war or economic uncertainty. During World War II, government agencies heavily promoted carpooling as a way to conserve limited resources such as gasoline and rubber for tires. Later, in the 1970s, the Organization of the Petroleum Exporting Countries (OPEC) instituted an embargo that caused a worldwide shortage. The oil crisis precipitated another major push to promote energy conservation and more efficient means of commuting.
Over the last three decades, however, carpooling has been on the decline. In 1980, it had a mode share of about 20 percent, but by 1990, its share had dropped to about 13 percent. By 2004, it was 10 percent and it has remained steady since then. Contributing causes could include a decrease in the real-term costs of driving and an increase in the percentage of the population with a driver’s license. Because more individuals have the means to own an automobile and a license to drive it, the appeal of carpooling has diminished. Flexible work hours, desire for personal convenience, and greater pressure to accomplish multiple things during each trip, requiring multiple stops, are likely contributors as well.
Even so, today’s commuters are looking for flexible, affordable commuting options. Some have turned to dynamic ridesharing as an answer.
What Is “Dynamic” About Ridesharing?
Dynamic ridesharing, also known as casual carpooling or slugging, is more flexible and less structured than traditional carpooling. The latter typically involves predetermined arrangements whereby participants agree to travel together, sharing the costs and often taking turns as the driver. Instead, dynamic ridesharing involves informal carpools that form when drivers and passengers meet at designated or at unofficial locations, typically near transit routes that provide parallel service.
“Dynamic ridesharing has the potential to revolutionize carpooling,” says Bob Arnold, director of the Office of Transportation Management in the Federal Highway Administration’s (FHWA) Office of Operations. “FHWA’s investments to pilot dynamic ridesharing--targeted especially to address social factors, quickly facilitate efficient pairings, develop user-friendly technologies, and utilize appropriate incentives and pricing--will help create a viable and desirable transportation choice in the [United States] in the near future.”
This type of ridesharing can take many forms. One is commuters meeting at unofficial gathering places along highways with high-occupancy vehicle (HOV) lanes. Another is using smartphone-based apps that facilitate finding rides, sharing expenses, and rating rideshare experiences. The informal nature broadens the appeal of carpooling by reducing the time and commitment required from drivers and riders.
Dynamic vanpooling, like dynamic carpooling, offers the potential to reduce vehicle trips by filling empty seats. According to U.S. Code, for participants to be eligible for tax-free commute subsidies, a vanpool must have the capacity to carry six adults in addition to the driver and have at least 80 percent of its mileage used for commuting purposes.
Dynamic ridesharing has a long history in the United States and is tied closely to the creation of HOV lanes, which came into existence in the 1970s in response to the pressures of energy scarcity. The Henry G. Shirley Memorial Highway (I–395) in northern Virginia was the first HOV-designated corridor in the country. The lanes started with bus-only restrictions in 1969, but then opened to four-passenger carpools (HOV-4) and eventually vehicles with at least three passengers (HOV-3).
HOV lanes provided the incentive for dynamic ridesharing, arguably the first major variation in carpooling since the large-scale adoption of the automobile in the United States. Within a short time of their introduction, HOV lanes had motivated commuters in San Francisco, CA, and Washington, DC, to start forming one-time carpools in the morning and also in the evening. The practice came to be known as “casual carpooling” in San Francisco and “slugging” in Washington.
Drivers wanting to use the HOV lanes began cruising by commuter bus stops looking for carpool partners, offering a direct, free ride to anyone going to the same destination. Riders realized they could get a free, faster (no intervening stops) trip, while drivers enjoyed the time savings benefit of HOV eligibility. The popularity of the practice took off from there. The systems grew organically, with no formal organization or outside entities guiding their development. In some locations, volunteer users set up Web sites to help standardize the norms of the practice, but overall it is a self-governing system.
Dynamic ridesharing thrives on a few factors. First, a congested corridor offering HOV travelers time savings and travel time reliability, or at least toll cost savings, is essential. HOV-3 restrictions make riders and drivers feel more comfortable carpooling with strangers. Having a third person in the vehicle helps offset the awkwardness and personal safety concerns that two strangers may feel when sharing a vehicle. Second, parallel transit services, even if slower and less frequent than desired, also are important as a backup option for riders if they miss the normal dynamic ridesharing hours. Lastly, for dynamic ridesharing to work, it is necessary for large groups of commuters to live in close proximity or have ready access to sizable park-and-ride lots near HOV facility entrances, coupled with densely packed work locations.
Casual carpooling in San Francisco centers on commuters who use the San Francisco-Oakland Bay Bridge to access downtown. By using the Bay Bridge, commuters reduce what would otherwise be a 35-mile (56-kilometer) trip around the bay to less than 10 miles (16 kilometers).
In addition, cars must pay a toll on all westbound lanes of the Bay Bridge. However, drivers may pay a reduced toll in certain reserved lanes by carrying three or more passengers on the westbound morning commute. Thus, drivers are incentivized to invite more passengers into their cars for the morning trip. Other commuter travel options include the Bay Area Rapid Transit (BART) train and commuter ferries across the San Francisco Bay.
Slugging, as dynamic ridesharing is known in Washington, DC, has as many as 25 different morning origin points in northern Virginia. Arlington and the District of Columbia have about a dozen morning dropoff points, which generally serve as evening origin locations as well.
According to David LeBlanc, author of Slugging: The Commuting Alternative for Washington, DC, the term “slugging” may have originated with bus drivers comparing people waiting to join carpools at bus stops to fake coins or “slugs” dropped in the fare box.
The slugging system is centered along the I–95/I–395 corridor, which has 27 miles (43 kilometers) of reversible-direction HOV-3 lanes that extend from Dumfries in Virginia to just shy of the District of Columbia border. Slugging participants, or “slugs,” can realize significant time savings by using the HOV instead of the general purpose lanes. In addition, slugs have a number of different backup transportation options, such as Metro trains and OmniRide commuter buses.
In Houston, TX, slugging occurs along two corridors--the Katy Freeway (I–10) and Northwest Freeway (U.S. 290). Similar to Washington, DC, the slug lines in Houston form in areas with ample parking, access to transit, and close proximity to HOV-restricted routes.
In addition, the city has fewer pickup and dropoff points than exist in northern Virginia and fewer pickup points than San Francisco. Slugging volume in Houston, moreover, decreased after completion of a freeway widening project in 2010, along with a policy reduction from HOV-3 to HOV-2 and conversion of HOV to high-occupancy toll (HOT) lanes.
Duplicating Dynamic Ridesharing
Many local governments, academics, and private entrepreneurs have expended substantial resources trying to make dynamic ridesharing work outside the corridors where it has sprung up organically. For example, several west coast cities tried to develop computer matching programs in the 1990s before widespread use of the Internet. But these efforts, which relied on land-line telephones and pagers, were short lived. (See “Lessons from Ridesharing Pilots in the 1990s” on page 19.) More recent efforts include stand-alone social networking-style Web sites and ridesharing apps for smartphones. In addition, some companies have tried to capitalize on popular existing social media platforms by offering rides among college students at the same university or employees of the same company.
“In the past year, there have been a number of developments in real-time ridesharing and dispatching services,” says Susan Shaheen, associate adjunct professor of civil and environmental engineering and codirector of the Transportation Sustainability Research Center at the University of California, Berkeley, and an expert on carpooling and vehicle sharing. “This has been facilitated through smartphone technology and social media, which can be used to match or link riders to drivers within minutes before a trip.”
The relative success and low cost of dynamic ridesharing have piqued the interest of researchers at the U.S. Department of Transportation (USDOT), who are studying the phenomenon with the goal of replicating or enhancing it with technology. For example, in 2010, FHWA’s Exploratory Advanced Research (EAR) Program sponsored a scan tour of the dynamic ridesharing sites in Houston, San Francisco, and Washington, DC. The scan team also met with transportation planners in the private and public sectors in those cities.
Observations and lessons learned from the scan include the following:
In 2012, the EAR Program also convened focus groups of dynamic ridesharers in the three cities. The focus group participants saw possible benefits to offering rewards of some type to ridesharers who take action to make the system function better. For example, suggestions included adding an option for return trips when not available, rewarding passengers for using more remote parking that is still within walking distance, and arranging for a “last call” backup van or taxicab service or rewarding drivers who pick up later in the HOV time period when riders risk getting stranded. Other ideas include prematching drivers and passengers, particularly for those using meet-up locations where dynamic ridesharing service is not reliable, and incorporating driver certification and ratings, especially for HOV-2 areas, to make passengers feel safer. The report is available at www.fhwa.dot.gov/advancedresearch/pubs/13053/index.cfm.
In addition, USDOT is sponsoring several ongoing efforts to promote ridesharing. The largest effort is through FHWA’s Value Pricing Pilot Program (VPPP), which underwrote several projects prior to program funding ending in fiscal year 2013 that combined ridesharing with financial incentives as a non-toll pricing strategy. Other USDOT efforts include initiatives from the department’s Small Business Innovation Research Program, Federal Transit Administration (FTA), and FHWA’s EAR Program. Details on these efforts follow.
Ridesharing and Financial Incentives
FHWA’s VPPP provides funding to support studies and implementation of projects to manage congestion on highways through tolling and other pricing mechanisms. Several ongoing projects combine dynamic ridesharing with pricing.
Santa Barbara, CA. A VPPP project in Santa Barbara, branded SmartRide, is implementing a technology-facilitated dynamic ridesharing project that includes a range of cash incentives to attract both drivers and riders to participate. The system is based on a GPS-enabled smartphone platform provided by a private sector partner, Avego, and is designed for commuters who travel on two congested segments of U.S. 101.
The project completed a beta test with 20 participants and the first phase of the pilot was directed toward college students. The pilot test targeted Santa Barbara City College students who live about 11 miles (18 kilometers) from the college in the community of Isla Vista. More than 400 students signed up at www.smartride.org, and more than 85 percent also downloaded the smartphone app and created a profile. Forty-three percent of those who signed up subsequently scheduled rides, and 30 percent posted a picture in their user profiles.
Project organizers report more than 100 users to date completing SmartRide trips and dozens of students regularly using the system. The project, now in its second phase, is focusing on encouraging more use of the app by the existing users and also increasing the number of users. The second phase targets commuters who work in the Santa Barbara area and live more than 30 miles (48 kilometers) away in neighboring Ventura County.
“The SmartRide dynamic rideshare value pricing pilot project has been incredibly insightful, showing us how travel behavior can be changed through the proper balance of mobile application technology and pricing incentives,” says Kent Epperson, director of traffic solutions for the Santa Barbara County Association of Governments.
Northern Virginia. To lessen the traffic morass along the I–95/395/495 corridor from Fredericksburg, VA, to Washington, DC, transportation officials are exploring innovative solutions such as dynamic ridesharing. A major impetus for this project is to mitigate traffic impacts associated with the U.S. Department of Defense’s base closure and realignment actions in the region. The process of reorganizing military installations involves job relocations and related roadway construction projects that are adding traffic to already jammed highway corridors.
The dynamic ridesharing project in northern Virginia, funded in part through the VPPP, includes a range of cash incentives to attract both drivers and riders. The project, focused on seven employment sites related to base closure and realignment along the I–95/395/495 corridor, aims to recruit 500 drivers and 1,000 riders for a 6-month pilot. As of April 2013, 400 individual users had participated.
Dynamic ridesharing software, coupled with GPS-enabled smartphones, facilitates finding and executing ride matches, tracking and recording journeys, and transferring money automatically. The money transfer is mostly from riders to drivers, although riders receive “credits” to spend before having to contribute their own funds.
The prevalence of slugging in northern Virginia, especially around the Pentagon, has familiarized the public, and particularly local employees of the military, with the benefits of dynamic ridesharing. Despite this familiarity, however, the project team had to overcome substantial challenges unique to operating at secure military facilities, such as site access and barriers to communication with prospective and current participants. The team overcame these challenges by establishing relationships with senior military personnel.
“We have proven that we can make this work with the military,” says Mark Gibb, executive director of the Northern Virginia Regional Commission. “The lessons learned about the technology, how to reach critical mass quickly, and ridesharing in general have been building blocks for better execution [of] a full-fledged program militarywide [and] regionwide…in northern Virginia.”
Austin, TX. The Texas Department of Transportation and the Central Texas Regional Mobility Authority are partnering to conduct a VPPP project in Austin to evaluate ways to reduce the impact of heavy toll-road traffic on non-tolled roads downstream. The FHWA-funded pilot includes incentives to attract drivers and riders to participate in a 12-month pilot. The project seeks to recruit participants who travel the tolled 183A and Manor Expressway, as well as non-tolled roads in the corridor. Candidate facilities include U.S.183, I–35, and Loop 1/MoPac Expressway. Three major employment centers are likely destination clusters located downstream: the Northwest Technology Center, the Arboretum at Great Hills, and downtown Austin, including the University of Texas at Austin.
The project will recruit 500 participants through targeted surveys asking for feedback on the use of toll discounts as an incentive to encourage driving on tolled roads during non-peak hours. The program also will test a real-time ridesharing application accessible through mobile and desktop devices. The program will dynamically match potential rideshare partners and provide toll-road rebates as an incentive.
The Texas A&M Transportation Institute will lead the evaluation. If successful, the project will be the first to both verify and execute high-occupancy toll discounts electronically.
Contra Costa County, CA. The ridesharing project on Contra Costa County’s I–80 builds on an existing project that is locally funded to engage employers located near Bay Area Rapid Transit stations in the county. The project extends the coverage of a preexisting pilot to provide discounted tolls--and faster trips--for carpools with three or more participants crossing one or both of the two tolled bridges in the corridor.
This VPPP-funded project aims to curtail the heavy traffic congestion on I–80 by deploying real-time ridesharing in a corridor with a history of casual carpooling. Some employers in the area already engage in ridesharing efforts. In addition, the corridor provides substantial backup transit service, including several Bay Area Rapid Transit stations, bus transfer facilities, and park-and-ride lots.
Partnering with Small Businesses
USDOT’s Small Business Innovation Research Program focuses on stimulating technological innovation while partnering with small businesses to meet Federal research and development needs to enhance the transportation system. As part of this program, in April 2011 FHWA awarded a contract (modified in October 2011) to Axiom xCell, Inc., to plan and conduct detailed preliminary design for a dynamic ridesharing system app in partnership with the San Diego Council of Governments and privately owned iCarpool. To enhance travel options and reduce congestion, the city’s council is searching for new approaches to verify vehicle occupancy on its I–15 HOT lanes. A dynamic ridesharing system app could provide for a verified and automated declaration of occupancy. When two individuals are confirmed by the electronic system as sharing a ride, which also is arranged by the system, the app automatically declares occupancy.
As part of the first phase of the project, the company and its partners wrote a concept of operations and a commercialization report. The latter concluded that there is potential for widespread use of a dynamic mobility app, developed perhaps in partnership with automakers, distributed through public agency programs (such as regional ridesharing agencies), and initially deployed with the support of large employer partners. Phase two will include development of a working prototype of the app, verification testing, and pilot testing in the San Diego region.
Integrating with Transit
FTA is addressing dynamic ridesharing through its Integrated Dynamic Transit Operations bundle of applications, an initiative jointly supported by the agency and the USDOT Intelligent Transportation Systems Joint Program Office. One of the applications includes a real-time method for connecting drivers with riders. In April 2013, the initiative brought in the Battelle Memorial Institute to develop a prototype and perform a demonstration of a dynamic ridesharing app that will enable drivers and riders to communicate electronically. The technology also will enable connections to other modes of travel, such as transit, if needed to complete the trip.
The application will use invehicle interfaces and hand-held devices. These innovations make this app differ from the existing technology, which uses mobile phone apps only. Combining existing mobile ridesharing applications with invehicle technology solves a number of problems associated with carpooling. For example, using a hand-held device to communicate ridesharing needs is fine for passengers but could lead to distracted driving for drivers because of the devices’ hands-on nature. By integrating ridematching functions into a vehicle’s onboard computer, voice-activated technology will enable drivers to find and accept potential ride matches along their routes with less diversion of their concentration from the roadway.
The project will develop requirements, architecture, and software in 2013 and then build and conduct component and field testing by spring 2014. Ultimately, it remains to be seen if an entirely new system, built from the ground up and utilizing new technologies and social networking tools, can yield comparable or even better results than the existing organic dynamic ridesharing systems.
Creating a Virtual Transportation Market
In 2010, FHWA’s EAR Program initiated another dynamic ridesharing project, called Engineering Tomorrow’s Transportation Market. A multidisciplinary team at the University of Southern California, with participants from the fields of operations research and computer science, are conducting the project, which aims to determine whether the market for dynamic ridesharing can be enlarged and generalized.
Rather than establishing fixed pickup and dropoff locations for ridesharing, the rise of smartphones offers the possibility of a virtual market where drivers and passengers can rapidly negotiate pickups and dropoffs anywhere--for a mutually beneficial price. The EAR project team is modeling and simulating potential demand to determine how the market might work (and what kinds of support it would require), how pricing would happen, and what the impact might be on travel by transit and personal vehicle.
The project is employing a variety of advanced computational -algorithms and techniques to explore how prices could be set fairly and efficiently in such a market, how the market could absorb effects such as trip diversions for pickup or dropoff, and how it might be feasible for a driver to pick up two or more passengers on the same trip. The simulation also explores how fast the real-time market system would have to work, the lead time that a driver or potential passenger might need to participate, the marginal cost for the driver who is picking up passengers, and how competition between drivers might alter the market prices. In addition to simulating and projecting the performance of such a market, the project team also is exploring possible impacts that the market might have at a regional level. The project is set to conclude in late 2013.
Seeding the Revolution
Dynamic ridesharing has the potential to substantially reduce peak-hour congestion by making it easy and beneficial for riders and drivers to fill the empty seats in commuting vehicles. Various USDOT efforts aim to expand existing dynamic ridesharing systems within their current service areas and add service to additional cities and regions. Smartphone-based apps, combined with carefully designed incentives, could help expand and sustain dynamic ridesharing, especially in areas with existing HOV or HOT lanes.
“As more and more Americans adopt smart mobile devices--and as traffic volumes continue to rise--interest in dynamic ridesharing as a safe, convenient, and beneficial travel option is likely to grow,” says Arnold.
Polly Trottenberg, Under Secretary of Transportation for Policy, agrees and underscores USDOT’s commitment to supporting the practice. “Ridesharing is a key tool to help alleviate congestion on our roads and highways--it’s good for communities, the environment, and overall quality of life,” she says. “The [U.S.] Department of Transportation will continue to support State and local agencies that are using this simple but effective means to improve mobility.”
Marc Oliphant is the regional employee transportation coordinator for the Department of the Navy, Naval District Washington. He studied at Brigham Young University and Virginia Tech and wrote his master’s thesis on dynamic ridesharing.
Allen Greenberg is a senior policy analyst with FHWA’s Office of Operations. Greenberg manages projects under the VPPP and Urban Partnerships program, focusing on usage-based auto insurance, variable and transparent demand-based parking pricing, and new forms of vehicle-use pricing and services (including carsharing, electric bicycle sharing, and priced dynamic ridesharing). He has a B.S. from Carnegie Mellon University in public policy and management and psychology, and a master’s in urban planning from the University of Virginia.
Ron Boenau is a senior transportation systems manager for the connected vehicle program in FTA’s Office of Mobility Innovation. Boenau focuses on intelligent transportation systems, automated vehicles, and standards. He has a B.S. from the University of Florida and an M.S. from the University of Maryland. He is an active slug line user in Washington, DC.
Jeremy Raw, P.E., is a travel modeling and analysis specialist in FHWA’s Office of Planning. He focuses on research, development, and deployment of improved analytic techniques to support metropolitan and State transportation planning. Raw holds degrees in engineering from Cooper Union and regional planning from the University of North Carolina at Chapel Hill.
For more information, contact Marc Oliphant at 202–685–8049 or firstname.lastname@example.org, Allen Greenberg at 202–366–2425 or email@example.com, Ron Boenau at 202–366–0195 or firstname.lastname@example.org, or Jeremy Raw at 202–366–0986 or email@example.com.
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