Editing Big Dig (section)

=== Lighting fixtures ===
In March 2011, it became known that senior MassDOT officials had failed to disclose an issue with the lighting fixtures in the O'Neill tunnel. In early February 2011, a maintenance crew found a fixture lying in the middle travel lane in the northbound tunnel.<ref name="Moskowitz-lights">{{cite news|first=Eric |last=Moskowitz |title=State says some light fixtures in Big Dig tunnels are flawed |url=http://articles.boston.com/2011-03-16/news/29350222_1_tunnels-fixtures-fluorescent-lights |work=[[The Boston Globe]] |date=March 16, 2011 |access-date=July 11, 2011 |url-status=dead |archive-url=https://web.archive.org/web/20110426004212/http://articles.boston.com/2011-03-16/news/29350222_1_tunnels-fixtures-fluorescent-lights |archive-date=April 26, 2011 }}</ref> Assuming it to be simple [[road debris]], the maintenance team picked it up and brought it back to its home facility. The next day, a supervisor passing through the yard realized that the {{convert|120|lb|kg|abbr=on}} fixture was not road debris but was in fact one of the fixtures used to light the tunnel itself. Further investigation revealed that the fixture's mounting apparatus had failed, due to [[galvanic corrosion]] of incompatible metals, caused by having [[aluminum]] in direct contact with [[stainless steel]], in the presence of salt water.<ref name=CorrosionGraphic>{{cite web |title=The Mysterious Corroding Big Dig Light Fixtures |url=https://www.boston.com/news/local/massachusetts/20110710_tunnels_light_fixtures/ |work=boston.com |publisher=The Boston Globe |access-date=April 9, 2012 |url-status=live |archive-url=https://web.archive.org/web/20120407223210/http://www.boston.com/news/local/massachusetts/20110710_tunnels_light_fixtures/ |archive-date=April 7, 2012 }}</ref><ref name=ENR-Salt>{{cite journal|last=Knapschaefer|first=Johanna|title=MassDOT Study Blames Salt For Big Dig's Fallen Light Fixture|journal=Engineering News-Record|date=April 27, 2011|url=http://enr.com|url-status=live|archive-url=https://web.archive.org/web/20151221233320/http://www.enr.com/|archive-date=December 21, 2015}}</ref> The [[electrochemical]] [[potential difference]] between stainless steel and aluminum is in the range of 0.5 to 1.0V, depending on the exact alloys involved, and can cause considerable corrosion within months under unfavorable conditions.

After the discovery of the reason why the fixture had failed, a comprehensive inspection of the other fixtures in the tunnel revealed that numerous other fixtures were also in the same state of deterioration.<ref name=Mullan-Light>{{cite web|last=Mullan|first=Jeff|title=Tunnel Safety Ceiling Light Fixture Update|url=http://www.massdot.state.ma.us/portals/8/docs/TunnelSafety/TnnlSafetyBoardRpt040611.pdf|work=Report to the MassDOT Board of Directors|publisher=MassDOT|date=April 6, 2011|access-date=April 9, 2012|url-status=live|archive-url=https://web.archive.org/web/20130701232403/http://www.massdot.state.ma.us/portals/8/docs/TunnelSafety/TnnlSafetyBoardRpt040611.pdf|archive-date=July 1, 2013}}</ref> Some of the worst fixtures were temporarily shored up with plastic ties.<ref name="54m-fix" /> Moving forward with temporary repairs, members of the MassDOT administration team decided not to let the news of the systemic failure and repair of the fixtures be released to the public or to Governor [[Deval Patrick]]'s administration.<ref name="Murphy-lights">{{cite news |first1=Sean P. |last1=Murphy |first2=Scott |last2=Allen |title=Worries about lights were kept in the dark |url=http://articles.boston.com/2011-07-10/news/29758587_1_light-fixture-tunnels-state-engineers |work=[[The Boston Globe]] |date=July 12, 2011 |access-date=July 11, 2011 |archive-url=https://web.archive.org/web/20110720145746/http://articles.boston.com/2011-07-10/news/29758587_1_light-fixture-tunnels-state-engineers |archive-date=July 20, 2011 |url-status=dead }}</ref>

{{As of|2012|April}}, it appeared that all of the 25,000 light fixtures would have to be replaced, at an estimated cost of $54 million.<ref name=54m-fix>{{cite news|last=Murphy|first=Sean P.|date=April 5, 2012|title=Big Dig needs $54m light fix|url=http://articles.boston.com/2012-04-05/news/31295327_1_new-fixtures-entire-fixture-light-replacement-project|work=boston.com|publisher=The Boston Globe|access-date=April 9, 2012|url-status=dead|archive-url=https://web.archive.org/web/20120406184648/http://articles.boston.com/2012-04-05/news/31295327_1_new-fixtures-entire-fixture-light-replacement-project|archive-date=April 6, 2012}}</ref> The replacement work was mostly done at night, and required lane closures or occasional closing of the entire tunnel for safety, and was estimated to take up to two years to complete.<ref name="54m-fix" />