Hidden winners and losers in the Lake Street signal plan

Some who live on or near the rush-hour-congested Lake St. corridor look to the proposed signal at the Minuteman Path for some traffic relief.

Unfortunately, the opposite result seems likely: heavier traffic, and more cut-throughs.

Cyclists stopped at red 

Welcome to the topsy-turvy, counter-intuitive world of traffic engineering. Perhaps orbital mechanics, where astronauts speed up in order to slow down, is as confounding to common sense.

Below is my list of likely winners and losers under this plan, which has its last public hearing next Tuesday.


Lake St. commuters. Although the promised 7-minute-per-trip improvement has shrunk to 4 minutes, and may be even less in end, it’s credible that rush-hour traffic would move a little faster.

Induced demand,” in which more drivers choose Lake Street precisely because things move a bit faster, would reduce this benefit, but not to zero.

Minuteman cyclists. At least some bicyclists would welcome the clarity  and certainty that a traffic signal provides. Note that cyclists are also losers, below, in several ways.

Cambridge and Somerville commuters. To the extent that the signal increases throughput at rush hour, it takes pressure off of an entire sclerotic system that includes the Alewife area.

Count on an army of robots (Wayz, Siri, and Google maps) to quickly and efficiently redistribute traffic as water seeks its own level. That means less traffic on the Alewife Brook Parkway and other roads, though the effect is likely to be small.

The Mugar project. Easing traffic means the traffic effects of this proposed housing development would be that much less acute.


Kelwin Manor and Mary St. neighborhoods. A goal of the new design is to increase throughput on Lake Street. That means more traffic.

If we assume that cut-throughs are proportionate to overall traffic volumes, then more traffic means more cut-throughs, a perennial issue for residents.

Faster-moving traffic on Lake could also make it harder for residents to enter the street at rush hour.

Hardy School neighborhood. Expect more cut-through traffic as a result of this plan, which would shift an evening bottleneck from Brooks Ave. to Mass. Ave.

The residential neighborhood bounded by Lake and Brooks would see an uptick in cut-through traffic from motorists seeking a way around this new logjam. Siri stands ready to help rush-hour traffic find this path.

Anyone struck by a car. Today’s traffic jam is horrible, but has this silver lining: a car that is not moving can’t knock anyone down. A plan to speed things up carries with it a greater risk of injury and death; the more speed, the more risk.

Cyclists on the path. At rush hour, a cyclist who just misses the green would have to wait nearly a minute for the next “go” signal. (The average wait would be half of that, and it sounds as though the impact of the light on cyclists off-peak would be minimal.)

Marathon St. residents. This street would be likely to see an uptick in cut-though traffic as more drivers chose Lake Street as a path to Somerville from Route 2.

Lake St. Commuters. Despite the real (if perhaps small) benefit from the proposal, the plan fails to address other factors that contribute to rush hour congestion here. One of these, the frustrating configuration of the signal at nearby Brooks Ave., is squarely within the scope of this project. It’s an unfortunate missed opportunity.

Arlington cyclists and pedestrians. Proponents plan to pay for this project with funds from the state’s Complete Streets program.

These funds are generally used to improve safety and mobility for cyclists and pedestrians, and there are plenty of unmet opportunities to do that in town. Using those funds for this project would shift those resources to improvements that benefit motorists.

Incidentally the estimated cost of this project has nearly tripled since the Selectmen approved the design phase in 2016, from $150,000 then to $400,000 now.

That’s how it looks to me. What, and whom, did I miss?

Thanks to Wikimedia Commons user Heb for making the above image available under a Creative Commons license.

5 comments so far

  1. Mark Kaepplein on

    The effects you predict can get fixed in phase 2 or phase 3 follow-on projects. Arlington has been making our roads only less efficient for the past 40+ years with narrowing, lane removals etc., so a series of projects to increase mobility for a change is long overdue.

    Its short-sighted to fear improvement because it could necessitate future improvements. Capacity improvements have been long overdue to Rt. 16, Lake, Pleasant, Mystic, Highland, Park, and Mass Ave. The center project was a half step – 1.5 lanes of capacity lost 25 years ago still needs to restored to Pleasant/Mystic crossing Mass Ave. and left turn lanes removed 40+ years ago should be restored to Pleasant Street. The HAWK crossing has worsened congestion on Mass Ave., creating a new choke point due to traffic signals too close together. Lockeland and Highland signals on Mass Ave are another example of gridlock caused by signals too close together.

    Selectmen made short-sighted decisions to block increased efficiency at the Lake/Mass Ave intersection which will be needed and end up costing much more money with just local funding. Blocking improvements by Selectmen added to Orvis/Brooks cut through volume. Vote accordingly.

    • Ray Jones on

      The town should probably improve Lake & Mass. Ave. before worrying about the bike path, then, rather than trying to increase flow toward a problem area. That would also help reduce cut-through traffic.

      It seems like most of your arguments about what should/shouldn’t be done rest on the assumption that the town wants more traffic through it, on Lake, Pleasant, and Mass. Ave., etc. Given the support for the Selectmen in terms of re-election after the Mass. Ave. project, and the recent Town Meeting decision to lower speeds to 25 mph town-wide, perhaps the majority of Arlingtonians don’t feel that it’s justified to try to increase the number of cars driving through town for its own sake.

    • Adam Auster on

      I’ll tell you, Mark. When I was drafting this post last week, I nearly listed you as a hidden winner under this plan, based on your past advocacy for widening Lake St.

      To the extent the signal succeeds in shifting the bottleneck from Brooks to Mass. Ave., you’ll have plenty of scope to do that again.

  2. Ray Jones on

    Thank you for such a concise and clear writeup.

  3. Larry Slotnick on

    The current bottleneck caused by the “necessary only when Hardy School has morning and afternoon pedestrian traffic” traffic signal should be one of the two primary objectives of any redesign efforts along Lake St. That signal, in its current operational form is , in my opinion, the greatest hindrance to the smooth flow of traffic during evening auto rush hour.
    The second greatest hindrance is the basic design of the Minuteman crossing of Lake St…. the improper signage (and lack modern signage), road and path striping (or lack thereof), obstructed views, etc all contribute to its inherent throughput inefficiency for automobiles. Make the proper upgrades and both motorists and cyclists will benefit once they adapt to the forced behavioral changes.
    I am not fearful of the Mass Ave/Lake St intersection…not of an increase in cut through traffic.

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