Editing Interstate 93 (section)

===Boston===
{{further|John F. Fitzgerald Expressway|Big Dig}}
[[File:Boston-big-dig-oldtraffic.png|thumb|left|Route of the original Central Artery, as well as other roadways affected by the Big Dig]]
[[File:Boston-big-dig.png|thumb|Route of the new Central Artery after the Big Dig]]
[[File:Tunnel-large.jpg|thumb|right|I-93 through the O'Neill Tunnel]]
[[File:Leonard_P._Zakim_Bridge_view_from_Causeway_Street.jpg|thumb|right|I-93 passing by [[TD Garden]] as it travels on the Zakim Bridge]]
[[File:South Bay Interchange.jpg|thumb|right|The [[South Bay Interchange]] (looking south) to the [[Southeast Expressway (Massachusetts)|Southeast Expressway]] with [[Great Blue Hill]] visible in the background]]
[[File:South Bay Interchange Closeup.jpg|thumb|right|alt=South Bay Interchange Closeup|A closer view of the South Bay Interchange]]

The [[Central Artery]], officially the John F. Fitzgerald Expressway, was a section of highway in Downtown Boston constructed in the 1950s and was originally designed as a fully [[elevated highway]]. This new highway was greatly disliked by the citizens of the city because it cut the heart of the city in half; cast long, dreary shadows; and was an eyesore to the community. Because of the public outcry, Governor [[John A. Volpe]] ordered the southern half of the highway redesigned so that it was underground; this section became known as the [[Dewey Square Tunnel]]. With the cancelation of the highway projects leading into the city in 1972 by Governor [[Francis Sargent]], the Central Artery gained the designation of I-93 in 1974. It has also carried the local highway designations of [[U.S. Route 1|US&nbsp;1]] (since 1989) and [[Massachusetts Route 3|Route&nbsp;3]].

By the mid-1970s, I-93 had outgrown its capacity and had begun to deteriorate due to a lack of maintenance. State Transportation Secretary [[Frederick P. Salvucci]], aware of the issues surrounding the elevated roadway, proposed a plan conceived in the early 1970s by the [[Boston Transportation Planning Review]] to replace the rusting elevated six-lane Central Artery with a new, more efficient underground roadway. This plan was merged with a long-standing proposal to build a third harbor tunnel to alleviate congestion in the [[Sumner Tunnel|Sumner]] and [[Callahan Tunnel|Callahan]] tunnels to [[East Boston]]; the new plan became known as the Central Artery/Tunnel Project or the [[Big Dig]].

These new roadways were built during a 12-year period from 1994 to early 2006. The massive project became the largest urban construction project ever undertaken in US history.<ref name="The Associated Press">{{cite news |url = http://edition.cnn.com/2006/US/07/12/bigdigdeath.ap/index.html |title = Review Begins After Big Dig Tunnel Collapse |publisher = CNN |date = July 12, 2006 |access-date = July 25, 2006 |archive-url = https://web.archive.org/web/20060715075257/http://edition.cnn.com/2006/US/07/12/bigdigdeath.ap/index.html |archive-date = July 15, 2006 }}</ref> Construction on the new I-93 segment was not without serious issues: a lengthy federal environmental review pushed the start of construction back from approximately 1990, causing many inflationary increases, while funding for the project was the subject of several political battles between President [[Ronald Reagan]] and Representative [[Tip O'Neill]]. Major construction on the new roadway was done while maintaining the old roadway, a step that also greatly increased the cost of the project. The original [[Charles River]] crossing, named Scheme Z, was the object of great public outcry similar to that of the building of the original highway. The outcry eventually led to the replacement of Scheme Z with a newer, more sleek [[cable-stayed bridge]] and complementing exit for [[Cambridge, Massachusetts|Cambridge]], increasing the cost even more.

In Downtown Boston, I-93 is made up of the [[O'Neill Tunnel]] and [[Leonard P. Zakim Bunker Hill Memorial Bridge]], which spans the Charles River. The underground construction of the tunnel system was completed as of October 2006; however, repairs continue to many parts of the tunnel due to water leakage because of improper construction of the [[slurry wall]]s supporting the O'Neill Tunnel. The former route of the above-ground Artery, so named "the other [[Green Monster]]" by Mayor [[Thomas Menino]], was replaced mostly by open space known formally as the [[Rose Fitzgerald Kennedy Greenway]].{{citation needed|date=December 2019}}

Additional improvements were done in the [[South Bay Interchange|South Bay]] section of the highway: the I-90/I-93 interchange was completely redesigned, a new [[HOV lane]] extending from the zipper lane in Quincy was added and the South Boston Haul road that was constructed to bypass truck traffic around residential streets in the South End was opened to general traffic.{{citation needed|date=December 2019}}

Hazardous cargos are prohibited from I-93 in Boston over safety issues in the tunnels; these cargos must exit at either the [[Leverett Circle]] connector when traveling southbound or at the Massachusetts Avenue exit when traveling northbound.{{citation needed|date=December 2019}}