Reducing Traffic Congestion in Nashville: Alternative Approaches


By Jason Zasky

Vanderbilt’s Malcolm Getz takes issue with Nashville’s nMotion transit plan, advocates using tolled express lanes to reduce traffic congestion in Middle Tennessee.

Malcolm Getz
Malcolm Getz

“Better transit doesn’t reduce traffic congestion,” asserts Vanderbilt University associate professor of economics Malcolm Getz in his recent commentary about Nashville’s nMotion transit plan. Titled “Car and Transit Futures in Nashville,” the twelve-page paper argues that more mass transit won’t solve Music City’s traffic congestion problems, taking particular issue with the expansion of rail service, which Getz regards as expensive and inefficient, especially as compared to other potential solutions.

“You can build transit and if it is well-designed it will attract transit-oriented people,” begins Getz, referring to the two-percent of Davidson County commuters that currently utilize mass transit, “but it’s been well-established that it will not reduce congestion, as traffic expands into whatever space is available.” Getz cites a landmark 2011 study titled “The Fundamental Law of Road Congestion: Evidence from US Cities,” which was published in The American Economic Review 101 and concluded that “increased provision of roads or public transit is unlikely to relieve congestion”( or more specifically, vehicle [miles] traveled).

“People have a certain tolerance for congestion and will congest up to that level of tolerance,” he explains.

Using Express Lanes to Reduce Congestion
Instead of focusing on expanding mass transit, Getz suggests introducing tolled express lanes on Middle Tennessee’s interstates. “The toll would vary with the volume of traffic. At peak hours the tolls should be high enough to keep traffic flowing and as traffic lessens the tolls should be quite low. The important point is that space on the roadway is valuable and the tolls reflect that value,” he offers.

Getz recognizes that “it takes a big mental shift to think of tolls [not] as a way of paying for the roadway but as a way of managing the use of a roadway,” yet the introduction of express lanes would engender other benefits as well. For one, tolls would encourage more carpooling and ride sharing, as the cost of the tolls could be shared. This would dovetail nicely with the increasing popularity of uberPOOL and Lyft Line (the carpooling/ride sharing services of Uber and Lyft, respectively), not to mention the introduction of Nashville-based Hytch, an app that enables users to earn cash whenever they share a ride.

Getz advises that tolled express lanes have successful reduced congestion in many other cities around the country, including Atlanta, Denver, Houston and Charlotte, before noting that the benefits can also accrue to mass transit. That is, buses can travel on the express lanes, too, allowing bus riders to enjoy a faster commute without requiring the construction of new lanes or facilities dedicated to buses.

Know too that vehicles would not need to slow or stop to pay tolls; each time a vehicle passes under an overhead gantry the signal from a small radio transponder on the vehicle windshield would record the toll, which would be deducted from the vehicle’s online account.

The Future of Mobility in Nashville
Yet another benefit of using digital technologies to enhance mobility is that they can have an impact on congestion in the near-term, as compared to, say, the construction of new rail lines, which wouldn’t be completed for many years to come. Though it’s a challenge to predict how technology will evolve and be implemented, it’s certainly conceivable that conventional transit like rail service could play a diminished role in the not-too-distant future.

“Philadelphia and Los Angeles are seeing 10-20 percent declines in transit ridership and observers believe a significant portion of this decline is due to [car services],” offers Getz, noting that the trend could be exacerbated by the development of autonomous vehicle technology.

“[The] successful launch of autonomous car-services will reduce the demand for travel by conventional transit by offering faster pick-up, point-to-point service, and around the clock availability,” relates Getz in ‘Car and Transit Futures,’ emphasizing that autonomous vehicles will be a part of our lives sooner than you might think. “Car-services with autonomous vehicles are likely to be operating in Nashville before a railroad service [can] launch on Gallatin Pike,” he concludes.