Small tweaks led to major changes in Mass. Ave. design

The Mass. Ave. design open house at the Hardy School on April 4

Sweeping amendments to the design for Mass. Ave. in East Arlington stemmed from two small technical changes instigated last summer, according to those involved.

The decision to add an unneeded travel lane to Mass. Ave. eastbound between Pond Lane and Linwood Street, and the removal of safety features from the Wyman St. pedestrian crossing there, began as a desire for extra queuing capacity for cars waiting at the Linwood signal.

Similarly, the consolidation of two pedestrian crossings in East Arlington into a single crossing with no pedestrian island is solely a consequence of a decision to honor a request by the owner of the Arlington Restaurant to move the proposed bus-stop location, freeing up two parking spaces in front of the diner.

These two minor changes had major consequences when the consulting engineers and the town’s Transportation Advisory Committee began to fit them into the existing design framework and philosophy.

These decisions were made in obscurity and even secrecy, and the changes were filed in February with Mass. Highway without any public notice until nearly a month later.

The Arlington Diner decision, before its greater consequences were known, had been discussed by the Mass. Ave Review Committee at its July 20 2011 meeting, but the staff elected to ignore the Committee’s advice that the bus stop should remain at the restaurant as the best location.

Linwood to Pond Lane: According to various members of TAC, the committee became concerned last summer that the queue for the Linwood St. signal would be unacceptably long on some mornings, based on traffic counts made by the Town’s consultants in 2008 and 2009. The committee’s solution was to add a lane to the approach to the intersection in front of Walgreens.

Subsequently, the Committee decided that the change had rendered the distance between the start of the one-lane segment at Pond Lane and its end in the approach to Linwood “too close,” so they made the whole thing two lanes.

However, no one connected to the plans believes that the extra lane is needed to accommodate traffic volume, the number of cars. By contrast the eastbound segment from Bates Road to Lake Street requires two full lanes to accommodate am traffic volume, according to the Town’s Functional Design Report.

There’s still a lot I don’t understand about this, but its clear that the traffic-queue issue is based on actual traffic counts and engineering principles. By contrast the “it’s too close” rule looks to be at best more of an intuitive thing, aesthetic preference, or habit.

Marathon to Milton: The Marathon St. crosswalk is heavily used and has been problematic. The 25% design filed last year would have made several important improvements here, including bump-outs and a pedestrian refuge island.

The proposed crosswalk at Milton would have been new and would have included two curb bump-outs.

Laura Wiener, the senior town planner assigned to the project, confirmed at Thursday night’s open house that the sole reason for the loss of these pedestrian safety features was to preserve two parking spaces in front of the restaurant by relocating the bus stop proposed there.

The simple relocation of a bus stop then collided with other design criteria and goals. These probably included such things as as maximizing parking for other businesses, locating bus stops at the far side of intersections, and keeping bus stops near crosswalks.

When the bus-stop move met those criteria it ramified into another major design change.

The Transportation Advisory Committee was involved in the Linwood decision but not this one, according to its vice chair, Ed Starr.

This project has been plagued by people who consider themselves qualified to know better than trained planners and engineers what can work and what can’t. I have no wish to join their ranks.

You and I are clearly qualified to judge, however, whether it’s worth giving up a pedestrian crossing and some safety features so that the Arlington Restaurant can have two parking spaces directly in front. That is not a technical matter, it’s a question of priorities.

At Linwood, I think we are qualified to understand the benefits of the “not too close rule,” if someone can articulate that, and similarly weigh those against the very real costs to pedestrian safety entailed by the new design there.

Update: Thanks to an alert reader for spotting an error. In the second paragraph I described an eastbound lane as “westbound.” I plead fatigue–and have fixed the error.

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7 comments so far

  1. Mark Kaepplein on

    Arlington Restaurant has a significant aged customer base. Supporting people with disabilities and impairments makes more close parking a priority. Any answer why pedestrians can’t get high intensity activated crosswalk signals? Not enough money left from curb widening in front of apartments between Grafton/Orvis and Winter/Lake?

  2. Mark Kaepplein on

    Queuing is straightforward. Two lanes can store about 2x the vehicles as one lane, resulting in a backup half as long waiting for a green light. This is good, resulting in less blockage of side streets and driveways and that traffic which might want to turn away from the red light. Long queues create a ripple effect that propagates downstream, creating more blockage and flow restriction.

    Screwing up the queuing and storage 25 years ago is why Pleasant Street backs up to Rt. 2 from Mass Ave. Pleasant has one lane of flow capacity in each direction. When a traffic light is inserted, traffic flows for about half the time, reducing the total flow rate to half. To get back close to the uninterrupted single lane flow rate, put two lanes of flow through the intersection with the traffic light. That alone won’t help until there is storage space for vehicles enough to keep flowing two lanes during the green light, because one feeder lane isn’t enough to maintain two lanes of flow.

    When Pleasant and Mystic were changed from two flow lanes each way with storage to just one through lane each way, the efficiency of the intersection crossing dropped by nearly half, resulting in backups in both directions and more traffic diverting through Jason Street(*). That extra traffic on Jason Street will become a much bigger problem when the Mill Street apartments are occupied and more vehicles try to turn left on Mass Ave from Mill.

    Since selectmen objected to any paint or traffic barrier trials of lane reduction, fail-proofing the design is more important. More so when they decided to make changes expensive to undo if they don’t work. Smarter lane reduction would have just been done with paint, so Arlington residents don’t have to pay so much to fix it afterwards. Instead, the road crown is not centered along with raised medians, and sidewalks are needlessly and excessively widened in many areas at apartment buildings with their own setbacks and landscaping.

    * – Pleasant and Mystic did not quite have two through lanes each way prior to the right lane being made for right turns only. The right lane was for going straight or right, making the total 1 1/2 lanes each way.

    I know queuing from computer science and packet networking. People with a physics background see roads with fluid dynamics principals, recognizing ripple and shock waves when flow is interrupted by a turning vehicle or traffic light. Particle and wave views both have their place.

    • Mark Kaepplein on

      Another example of how a single traffic lane going to two at signaled intersections are a win is where Broadway crosses Rt 16. Broadway on both sides of the light has storage area and 1 1/2 crossing lanes – the right lane is also used for right turns. After the light, traffic has an area for the two lanes to merge back to one. A return to this is what is needed at Pleasant and Mystic where crossing Mass Ave.

  3. Mark Kaepplein on

    I wish government and transportation projects would join the Internet era. There is no reason why documents, drawings, issues, mini surveys, and suggestions can not be available online, tracked, and responded to by many. Now comments enter a black hole, and if answered, its not documented for everyone to get the answer. When a new drawing is put online, more questions than answers get generated because the whole process is opaque to citizens. There is a huge opportunity to build community through project involvement instead of mistrust when all is hidden. All these tools are already written and available, many free as open source.

  4. Jean B. on

    I am reminded of a thought I have had. There is concern re the morning backup into Arlington, but no concern about the lengthy evening rush-hour backup into Cambridge, in spite of the fact that many of the folks in that line will be going home to Arlington.

    Some years ago, there were temporary barriers at the intersection of Park Ave., Lowell St., etc. I thought it was brilliant to assess the affect of a plan on traffic BEFORE it became a fait accompli. Why is there no similar trial planned before the Mass. Ave. redesign is implemented?

    • Adam Auster on

      Jean, I understand why people are skeptical about traffic counts (which in this case indicate that the westbound traffic at that point only needs one lane).

      I invite you to do as I have done: stand on the sidewalk on the Arlington side of that intersection and see for yourself.

      It’s really clear from there that the bottleneck in Cambridge is caused by the signal at Route 16, that a great deal of traffic stopped there turns north and does not enter Arlington, and that another lane (in the design) would be superfluous.

      Don’t take my word for it, go see for yourself!

  5. Donna Janis on

    Jean, you are right. Your commonsense suggestion of doing a traffic mock up with temporary barriers has been made to the Selectmen and Planning Department many times since 2009, to no avail. Personally, I think they dread the results any temporary barriers would reveal. I think this is also why Greeley et. al. declined to allow voters to express an opinion about the Corridor Plan traffic lane removal on the April 10 ballot.

    I often return to my Mass. Ave. home via Cambridge and agree with you that the back up in Cambridge at the Route 16 light is going to be horrendous. Crossing into Arlington westbound, we’ll merge immediately to one lane and soon encounter the first bus stop on the right. How often do buses pull all the way into a bus stop? If the rear of the bus sticks out, it will block traffic and the bike lane. There are driveways and streets on the left, and each time a car stops to take one of these lefts, traffic will be in a conga line behind it. For instance, my driveway is on the left. My vehicle is 6 1/2 feet wide. The westbound lane at this point looks to be approx. 11 feet wide. So, when I sit with my left turn signal on, waiting for the eastbound traffic to clear to let me into my driveway, cars will not be able to go around me as (assuming I’m just 6 inches from the middle yellow line) there will only be 4 feet or less of remaining traffic lane to my right. Allowing for my side mirror, cars that insist on going around me will have to pull at least two feet or more into the bike lane, which is illegal and dangerous. And, if there is a bus or truck behind me, they will be unable to pass by and everyone will have to sit until I make it into my driveway. Now, multiply this scenario times the many left-turning homeward bound commuters who live on the east side of Mass. Ave. Anyone who thinks there won’t be back ups with one westbound lane is dreaming.


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