I-90 Westbound Clarendon On-Ramp to Close

The I-90 Westbound Clarendon Street on-ramp will be permanently closed effective midnight Tuesday, Sept. 3, according to a Massachusetts Department of Transportation representative.

Andy Paul, a MassDOT state highway design engineer, told a small group of citizens in attendance at an Aug. 27 public meeting at the Copley Branch of the Boston Public Library that the closure, which has received approval from the Federal Highway Administration, was on account of the ramp’s structural and safety deficiencies.

Paul said it neither meet MassDOT’s minimum threshold of 1,000 feet between the next nearest ramp, nor did it satisfy the minimum required ramp length of 457 feet.

The “sight distance,” which Paul defined as “the speed of the roadway and distance you travel at that speed,” was only 240 feet – far below the minimum requirement of 1,030 feet.

Moreover, the ramp’s “merge length” of 100 feet is also “substandard,” Paul said, and “all of this leads to safety issues.”

Between 2013 and 2015, the I-90 Westbound Clarendon Street on-ramp had four times as many vehicular crashes, compared with nearby on-ramps at Arlington and Dartmouth streets (10 crashes per 1 million vehicles, compared to 2.5 crashes per 1 million vehicles), Paul said.

Moreover, Paul pointed to the ramp’s relatively low level of usage, with around 50 vehicles per hour, or slightly less than one per minute, during the morning peak hour; and about 130 vehicles, or slightly more than two vehicles a minute, during the evening peak hour.

To notify drivers of the closure, Paul said temporary signage and barriers to prevent access to the ramp would be installed around the site area during construction, which is expected to last about two weeks, while permanent electronic signage and a small permanent barrier would be put in place afterwards.

Paul also said MassDOT would notify GPS providers of the ramp closure, as it typically does to steer drivers away from work zones and bridge closures.

In response to an inquiry from a StreetsblogMASS reporter as to whether the ramp closure would benefit Boston Properties in its planned $1 billion redevelopment of the Back Bay MBTA station and the surrounding city block, Mark Boyle, of MassDOT, responded that it would be a boon for both the developer and taxpayers.

Besides already contributing $37 million to MassDOT and pledging another $20 million with the construction of the next major component of the project (i.e. the second of three potential towers), Boyle said Boston Properties has also provided space at another location to make upgrades to the Prudential Tunnel.

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