Runner Up: I-93 North HOV Lane Compendium Summary Draft


by Conrad Crawford


Greater Boston has the worst traffic congestion in the United States.1 The typical driver wastes more than $2,200 each year stuck in traffic. Traffic is holding back our economy and hurting our quality of life.2 According to recent polling from the MassINC Polling Group,3 two-thirds of drivers have rearranged their schedule to try to beat traffic, and about one-third have considered leaving the region entirely because of their frustration with our transportation system. Interstate 93’s “Northern Expressway” was completed in 1973. The highway bisects Medford, Somerville, and Cambridge, north of Boston. Originally envisioned to accommodate just 45,000 vehicles per day each way,4 it now carries on a typical weekday between 75,000 and 85,000 in each direction.5 Average daily traffic counts have grown by more than 25% since 2012. Research shows that burning gasoline and diesel fuel releases particulate matter, nitrogen oxide, carbon monoxide, and volatile organic compounds.6 This tailpipe exhaust increases risks of cancer, asthma, heart disease, and pre-term births. People living within 1,000 feet of a highway are most at risk, but vehicle emissions can travel up to a mile away. Traffic congestion compounds the negative impacts, and residents of Medford, Somerville, and Cambridge bear the greatest risk. In addition to creating public health problems, Boston’s congested highways contribute to climate change. Transportation is the largest source of greenhouse gases of any sector of the Massachusetts economy, comprising more than 40% of total emissions. Idle car engines also contribute heat to already warming urban climates.

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Since the late 1990s, the Northern Expressway has included a 2.6-mile HighOccupancy-Vehicle (HOV) lane in its southbound direction. The lane starts in Medford and is physically separated from the general lanes until the Zakim Bridge in Cambridge. On weekdays from 6:00AM to 10:00AM, the lane is reserved exclusively for vehicles with at least two occupants (HOV2+). Outside of those hours, it serves as a general-purpose lane open to all. The HOV lane is enforced by State Police.  Because of the higher occupancy per vehicle, the HOV lane moves more people, in fewer vehicles, than general purpose lanes during peak periods. The latest analysis shows that the HOV lane moves an average of 2,250 people per hour, with vehicles taking about three minutes to traverse it. Each general-purpose lane moves an average of 1,500 people per hour, with vehicles taking about ten minutes to go the same distance.7 The HOV lane is working. However, the lane is still “underutilized” in that it could accommodate some additional vehicles without degrading the speed and experience of existing HOV users. Because of this underutilized capacity, in May 2019, MassDOT decided to temporarily eliminate the HOV lane and open it to general-purpose traffic at all times, arguing that this capacity could be used by commuters avoiding the Tobin Bridge’s active construction zone. This action, however, seems to run contrary to a key recommendation of the Governor’s Commission on the Future of Transportation: that the state needs to focus on moving more people, not more vehicles.8 MassDOT is right to identify the HOV lane’s extra capacity as an opportunity, but the agency’s decision to eliminate the lane squanders that opportunity rather than leveraging it. Now that it is open to all vehicles, the lane will likely become oversubscribed by the crush of single-occupancy vehicles using I-93.


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Dynamic road-pricing is a market-based reform of a poorly utilized public asset. Converting the I-93 Northern Expressway’s 2.6-mile HOV lane to a dynamically-priced Tolled Express Lane at some or all hours of the day would ensure the free-flow of vehicles. At times when the general-purpose lanes are congested, users of the priced lane would be guaranteed uncongested travel of at least 45 miles per hour, but would pay a higher toll in exchange. At times of less congestion, the HOV lane price would go back down. MassDOT could choose one of two options:  

Option 1: Full conversion to a 24/7 Tolled Express Lane, eliminating accommodations for high-occupancy vehicles: This would be the simplest option from an operational perspective and might deliver greater benefits, though it would represent the more radical shift from past practice. Under this option, the exclusive availability for HOV2+ from 6:00AM to 10:00AM on weekdays would be eliminated. Instead, any and all vehicles choosing to pay a variable toll to use the lane would be allowed to do so. Drivers would be guaranteed a fast trip on the Express Toll corridor, but in exchange would pay a rate that fluctuates depending on real time demand. The lane would operate 24 hours a day, 365 days a year. Prices would be low (perhaps a minimum of $0.25 for the 2.6-mile trip) during off-peak periods, but increase significantly during busy rushhour periods when the demand for the road is high. 


Option 2: Conversion to a Tolled Express Lane outside of existing HOV2+ hours: This option would preserve the exclusive reservation of the lane for HOV2+ vehicles from 6:00AM to 10:00AM on weekdays, consistent with MassDOT’s long-standing practice. But outside of those hours the existing “free” lane would convert to a tolled express lane for all vehicles (with no preference for HOV2+ at these times). This option would be somewhat more operationally complex, as it would require strong and clear communications with drivers about whether the lane was “available” for non-HOV vehicles. However, enforcement would be similar to what it is today, and it would remain open to all vehicles for the 20 hours each weekday outside of morning rush-hour (as long as drivers are willing to pay the toll). There are many examples across the country of state departments of transportation converting existing HOV lanes into Tolled Express Lanes. The Federal Highway Administration (FHWA) has approved at least eight HOV conversions in the last few decades, including in California, Colorado, Florida, Minnesota, Texas, Utah and Washington.



The costs of a well-run electronic tolling system are negligible compared to those of constructing new highway capacity. Using FHWA data11 to calculate capital and operating costs for converting the HOV lane to a tolled express lane, rough estimates show that conversion will generate sufficient revenue to offset the capital and operating costs of the project. The table below lays out estimated capital costs, operating costs, and revenue for Option 1 (full conversion to a 24/7 Tolled Express Lane). These estimates indicate that the priced lane could produce an operating surplus of $1.6 million per year, providing MassDOT a roughly two-year payback period on its capital costs. Option 2 would have similar capital and operating costs, but would produce less revenue, and would have a longer payback period. Both options would be integrated into the state’s existing EZ Pass and open-road-tolling systems. 

Once up-and running, the priced lane would be among a small number of MassDOT programs producing revenue in excess of costs. These revenues would pay back startup costs of less than $4 million, which could come from MassDOT’s $18 billion five-year capital plan. 



MassDOT would need to receive approval from FHWA and the Massachusetts Department of Environmental Protection. However, the recent change in the status of the HOV2+ lane demonstrates regulatory feasibility. Converting to a tolled express lane would also likely require state legislation, both to enable or mandate the new toll and to specify the uses of any net revenue. This could either be done as a standalone “session law”, or as a change to Section 13 of Chapter 6C of the General Laws. 



First, by efficiently moving vehicles at a consistent speed, the Tolled Express Lane would improve traffic flow and reduce congestion for commuters and other road users. Second, improved traffic flow will reduce air pollution in communities that have long borne the brunt of tailpipe emissions.12 Third, the use of pricing to manage demand would create a test case for other state roads, bring MassDOT more in line with peer agencies, and build the necessary institutional expertise. A successful pilot would advance the road-pricing conversation. Conservative thinkers have long-supported road pricing because it is a market-based reform of a poorly-managed government resource, the public rightof-way. In 1993, the Reason Foundation wrote, “A consensus is emerging among transportation economists that the best way to deal with freeway congestion is to charge for driving during peak hours…[a Tolled Express Lane] would utilize more of the lane’s capacity, demonstrate congestion pricing on a wide scale, and generate revenues.”13 More recently, progressive advocates have begun to rally around road pricing for its justice and environmental benefits.14 Finally, the net revenue generated could mitigate the detrimental effects of I-93 on nearby neighborhoods by enabling investment and improving equity. For example, net revenue could be used to fund public transportation, biking, and walking improvements in Medford, Somerville, and Cambridge, options that could be used by residents and commuters alike. Revenue could also be used to fund investments to grow and maintain urban tree canopy or high performing green infrastructure that filters harmful pollutants and improves local air quality.



  2. story.html 
  3. 5cc043534192025ff55e3892/1556104021235Report+2019+03+Barr+T ranspo+Issues.pdf 
  7. Trends.html 
  10. involving_tolls/hot_lanes/index.htm 
  11. ID/51762470144A12B28525731E0068506C 
  12. articles/2018-04-10/better-air-means-better-health-in-somervillemassachusetts 
  13. files/22b593c21e642143157e65dc5223ce9a.pdf 


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