The answer to this question could determine the fate of Kelley Square redesign

Discussion about the redesign of Kelley Square has focused on the "peanut" design, crosswalks and bike lanes. But there's a more fundamental question that could determine whether the project succeeds or fails.

With MassDOT preparing for its May 22 public hearing on the final design, it's a good time to highlight an often overlooked element of the redesign and see if we can figure out what the effect will be.

Page 21 of MassDOT's presentation for the 25% design public hearing in February dealt with Vernon Street at I-290. The page contains this note, which has appeared in nearly every public record about the project, "Left prohibited from I-290 WB off-ramp."

Uh oh.

The big question is how do the people who live south of Vernon Street and Winthrop Street (see below) get where they want to go?

MassDOT assumes, in public documents, that it expects the traffic that would normally take a left turn on the Kelley Square off ramp to go over the bridge and up Vernon Street would exit I-290 on Harrison Street.

OK, let's start there (below).

There are two choices, left or right. Let's make a left.

Option 1

A left on Harrison Street brings traffic to Providence Street. For those needing to get south of Vernon or Winthrop streets this requires three four-way intersections, at Harrison and Providence streets as well as Dorchester Street (below) and at Winthrop Street (far below). [Thanks to JOSEPH Losapio, who points out there is also a four-way at Harrison and Providence streets.]

After that, traffic to a street such as Alpine Street has two choices, continue down Providence to Spur Street or drive down Winthrop and make a left turn of greater than 45 degrees to continue on Vernon Street.

Neither of those options is great, but overall the biggest traffic increase would be on Providence Street, the biggest backups at the Providence Street intersections at Dorchester and Winthrop streets, and the intersection of Winthrop and Vernon.

Now let's go back to the Harrison Street exit.

Let's look at Option 2, making a right turn.

Option 2

Drivers could head to Kelley Square to cross the Vernon Street bridge as they currently do. That traffic would cross Water Street and take a left onto Harding Street (below).

At this point it's worth noting how busy Harding Street already is. MassDOT, in its October public meeting presentation, points out that Harding Street carries the third-highest volume of cars into Kelley Square after Madison Street and Vernon Street (below). As an aside, if you zoom in on the photo below, notice there six cars on the off ramp, five of which are preparing to make a left turn to go up Vernon Street.

The layout of the "peanut" roundabout (below) suggests that traffic heading to Water, Vernon or Millbury streets should be in the left lane. The photo below was taken from MassDOT's "Kelley Square Reimagined" video.

Each car that enters Kelley Square from Harding Street that does not continue on Green Street or down Madison Street will slow traffic heading into either the Canal District or to Polar Park. MassDOT apparently understands where the Harding Street traffic will go because in its video, beginning at :12, all three cars that enter Kelley Square from Harding Street loop around to either Vernon Street or Water Street.

The upshot is that it's possible that blocking the left turn off 290 could increase traffic in Kelley Square. And while it's possible much of that traffic would go to Providence Street, there are two additional reasons to believe traffic in Kelley Square will still increase.

First, Jefferson Street, which is the first street after you cross the Vernon Street bridge (below). Jefferson Street is one way, up hill. It's hard to believe traffic would loop around Providence to Winthrop to Vernon to head uphill, although the city could make it a two-way street.

Second, with Millbury Street set to change direction, heading away from Kelley Square, it's possible the preferred way home for people who live south of Vernon Street would be to travel down Millbury Street and use the tunnels on Endicott or Seymour streets (below, left and right).

As bad as all these options may be, they are all still preferable to the nightmare scenario.

Nightmare scenario

For drivers used to taking a left off the Kelley Square off ramp, it's possible they avoid the Harrison Street exit all together and continue to exit at Kelley Square. The proposed traffic light at the end of the off ramp should lessen the likelihood of a free-for-all and make entrance to Kelley Square easier than entering it from Harding Street.

The upshot of that would be that the effort to reduce congestion in Kelley Square would actually increase it since those currently turning left and avoiding Kelley Square would now be entering it.

The bottom line is that no one will know for certain how the seemingly minor change (no left turn off I-290) meant to make Kelley Square easier to navigate will work until it's done. And while it's possible that traffic will steer clear of Kelley Square, it's not out of the realm of possibility it makes congestion worse.

(Update: Pauline Madera made these important points: "In all of the pictures there are no tractor trailers that are so common in Kelly Sq. since the CSX terminal destroyed Grafton Hill. So when the 18 wheelers can't take a left turn from the I-290 WB off ramp, now they will be in the residential areas of Vernon Hill as they try to find their way back to Grafton St. For those who will exit at Harrison St and use Providence St., to navigate south of Vernon St. you can get prepared now for back ups on Harrison St. when school is in session and the school crossing guard intentionally stops traffic on Providence and Dorchester Streets to allow children to get to Union Hill School on Dorchester St. But then again that only happens twice a day for 9 mos. of the year.")