After studying the potential impact of self-driving vehicles on Boston traffic, a consulting group concluded that they could have a number of benefits, including reductions in travel times and congestion. However, researchers also determined that there could be some drawbacks to the increased use of autonomous vehicles, including the potential for more urban sprawl.

The Boston Consulting Group, a global management consulting firm, recently published a report in association with the World Economic Forum entitled "Making Autonomous Vehicles a Reality: Lessons from Boston and Beyond." This is the fourth report the two entities have published on the impact autonomous vehicles could potentially have on urban mobility.

The latest report says Boston is a good city to analyze the effects of driverless vehicles because of its robust technology sector, openness to innovation, and mix of public and private transportation. It says the city's unusual street layout and harsh winter conditions are also good for studying the limitations of autonomous vehicles.

The Boston Consulting Group—together with the World Economic Forum, Boston city officials, and the Massachusetts Institute of Technology Media Lab—developed a traffic simulation model for a 0.45-square-kilometer area around City Hall in downtown Boston. Two scenarios were then introduced to this model. In one, autonomous taxis and personal vehicles were used for one-third of the trips in the area, while traditional personal vehicles, public transit, and traditional taxi and ride hailing services accounted for the rest. In the second model, public transit accounted for about one-third of the traffic while autonomous taxis and shuttle buses were used for all other traffic.

In the first scenario, the number of vehicles on the road and average travel time both fell by 11 percent compared to Boston's current travel flow. The model also determined that carbon dioxide emissions fell by 42 percent while the number of available parking spaces increased by 16 percent.

Under the second scenario, which modeled a disruptive shift where all transit was shared and autonomous, the number of vehicles on the road dropped by 28 percent while the average travel time fell by 30 percent. This scenario also resulted in a two-thirds reduction in carbon dioxide emissions and a 48 percent increase in available parking spaces.

However, the report also highlighted some downsides to the widespread implementation of autonomous vehicles. One potential effect could be a rise in urban sprawl, caused by residents opting to live farther away from the workplace due to easier and less stressful commutes. The report notes how the reduction of traffic congestion could be less pronounced if empty autonomous vehicles remain on the street while waiting for a passenger instead of incurring parking costs.

The report offered five key considerations for urban planners who are looking into the effects of autonomous vehicle implementation. These included understanding their own city's unique infrastructure and needs, having a digital platform to aggregate all modes of transportation, establishing a governing structure and testing policy to address transportation challenges, considering third party operators instead of municipal ownership of transportation assets, and incorporating multiple forms of autonomous vehicles, including taxis, shuttle buses, and private vehicles.

Boston is currently in the midst of a joint effort between the city government, Boston Consulting Group, and World Economic Forum to establish a strategy, programs, and other mechanisms for incorporating driverless cars into Boston traffic. The project has included the testing of autonomous vehicles on the roads of Raymond L. Flynn Marine Park using the Cambridge-based software NuTonomy.

Boston has also released a Go Boston 2030 plan, which aims to reduce solo car use by half and have this type of traffic account for only 20 percent of the city's commutes. The plan also hopes to increase commutes via public transit, walking, and biking.

"Boston is a great example of the type of multi-stakeholder cooperation required to successfully develop new mobility business models – models that can help cities solve their most pressing transportation challenges and improve livability for their residents," said Nikolaus Lang, senior partner at the Boston Consulting Group and co-author of the report. "The speed with which the city has moved from initial announcement to piloting has been impressive."