Closing HOV lanes is hard to understand

Adding highway capacity just increases traffic

IMAGINE FOR A MOMENT that you are on a diet – not a New Year’s resolution diet that lasts for nine days, but a serious, honest-to-goodness effort to change your eating habits. One thing is certain: you won’t reach your weight goal unless you start eating smaller portions. Portion control is a proven way to reduce calories, and many dieticians suggest that you use a smaller plate as a guide. That smaller plate will prevent you from filling typically oversized dinner plates to the groaning point. That seems fairly obvious, doesn’t it?

Well, the same thing is true for roads and highways.  Making highway capacity larger to manage or reduce traffic congestion – the equivalent of giving a dieter a larger dinner plate – won’t solve the problem.  The extra highway space will quickly get filled up by induced traffic, just like the larger dinner plate will quickly get filled with more food than you need to eat for a satisfying meal.  The dieter won’t lose weight, and the traffic congestion will get worse. It isn’t hard to understand.

What is very hard to understand is the approach taken by MassDOT’s highway department to manage traffic in the metro Boston “inner core” communities.  You’d think that MassDOT would be fully on board with the recommendations made by the governor’s Commission on the Future of Transportation, and indeed the message delivered by the governor himself: our transportation system needs to move more people, not more vehicles.  “Moving people not vehicles” is a shorthand way of saying: if we are serious about supporting a growing economy by reducing traffic congestion, improving air quality, and expanding modal options for people across metro Boston, our state transportation officials need to promote a sustainable mobility system that prioritizes moving more people. To move more people, you must do so with the modal efficiency provided by a high occupancy vehicle – a bus, a train, even a carpool.  That is the transportation version of literally doing more with less.

Inexplicably, the highway department has turned away from one useful tool in the congestion-reduction toolbox – high occupancy vehicle lanes (HOV lanes) designed to encourage and reward the use of buses and carpools.  They have abandoned the HOV lane heading north off of Frontage Road that was designed to encourage carpooling and bus use for commuters traveling from the south into the Ted Williams Tunnel. In so doing, they transformed a highly efficient and visible sustainable approach to driving into another congested highway ramp. Earlier this week, highway department officials “temporarily” eliminated the HOV lane on Interstate 93 from Medford to Boston because they fear that traffic frustrated with construction delays on Route 1 and the Tobin Bridge will divert to the interstate.  That is a peculiar way to think about how to manage traffic – well, peculiar for the 21st century.

There’s no evidence that MassDOT did any specific modeling to understand the impacts of their decision to abandon HOV lanes, nor is there evidence that they carefully considered a variety of alternatives. Their attitude, as reported, appears to be “this may work so let’s wait and see what happens.”

Rather than waiting, we might turn to data, which tell us clearly what happens.  As reported by Angie Schmitt in a 2017 Streetsblog USA post, a Transportation Research Board team found that “for every 1 percent increase in highway capacity, traffic increases 0.29 to 1.1 percent in the long term (about five years out), and up to 0.68 percent in the short term (one or two years).” Another study found “a one-to-one relationship between new highway lane capacity and traffic increases.”

Here’s what happens when you take out an HOV lane, either permanently or temporarily. You aren’t actually adding a lane, something we have no capacity to do. You are adding a fraction of a lane if you assume that the HOV lane had spare capacity.  And because we know that commuters have responded to HOV lane policy and were using that lane, we are now inducing them to revert to single occupancy vehicles – so we may literally end up moving more vehicles without moving a single additional person. “If you build it, they will come” is a proven truism –  no longer just about Midwest cornfields but about traffic management policy that adheres to the view that adding capacity improves traffic conditions.

There is no evidence, none at all, that the removal of HOV lanes does anything but induce more traffic. It simply spreads out the pain and, while doing so, adds significant pain to those who have attempted to make their daily commute in a more sustainable way. MassDOT knows this because MassDOT has studied this. In a recent report from the Lower Mystic Regional Working Group, which MassDOT supported and participated in, the possible conversion of the I-93 southbound HOV lane to a general traffic lane was determined to require a change in state environmental regulations in part because it would just “have the negative effect of increasing travel times for buses and carpools.”

Every commuter who takes a bus or drives in a carpool is seriously disadvantaged by this anti-HOV policy. Indeed, every resident of Greater Boston is disadvantaged and harmed by this policy because it affects the quality of the air we breathe, making it harder to achieve the climate goalposts we have set for our state by reinforcing behavior that we should be trying to discourage.  It is frankly a surprise that the policy doesn’t, on its face, violate state and federal clean air laws.

Each time a person commutes in a single occupancy vehicle, they add to the problem, contributing to more congestion, more delay, more lost time and wasted fuel. Encouraging people to move to a more sustainable commuting method, whether in a carpool or on a bus or a train, is an important way for state transportation officials to begin the process of combatting chronic traffic congestion.

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The pathway forward is clear and supported by real evidence.  Road pricing effectively reduces demand for limited road space, while the availability of alternatives like HOV lanes provide real incentives for drivers to think and act differently. (Parking availability plays its own significant, sinister role driving traffic congestion, but I will leave that topic for a future article.)

We thought we had reached a rare opportunity moment when the governor and his chosen team of advisors told us, last fall, that they were aligned in their thinking about how to prepare Massachusetts for a future where economic growth is supported by a mobility system that improves access by moving more people, not more vehicles. That pathway is still before us, achievable in an era when people want to have more sustainable mobility choices. The highway department has thrown a barrier in the way of our success, and it ought to be directed to alter its anti-HOV policy and reopen and expand (where feasible) all existing HOV lanes in the Commonwealth.

James Aloisi is a former state secretary of transportation, a principal in TriMount Consulting, and a member of the TransitMatters board. Josh Fairchild, president of the TransitMatters board, contributed to this article.