Big Dig, Central Artery/Tunnel Project (CA/T)

Big Dig or the Cen­tral Artery/Tunnel Project (CA/T) is a mega-project in Boston, Mass­a­chu­setts and it’s con­sid­ered one of the biggest civ­il engi­neer­ing projects in the USA. It con­sists of sev­er­al project tasks, includ­ing the depres­sion of Boston’s Cen­tral Artery (I‑93) and the con­struc­tion of a 3rd tun­nel to Logan Air­port under the Boston Har­bor. It turned the ele­vat­ed high­way I‑93 into a 3.5‑mile tun­nel under the city, while at the same time, the traf­fic with­in the city remained uninterrupted.

The main pur­pose of the big dig is to alle­vi­ate the pres­sure of high­way traf­fic. In late 20 cen­tu­ry, the traf­fic con­ges­tion rate of Boston become so high that the traf­fic crawled for more than 10 hours a day and the asso­ci­at­ed acci­dent rate is 4 times the nation­al aver­age, which leads to a con­sid­er­able annu­al cost for the high­way. Under this cir­cum­stance, Fred­er­ick P. Salvic­ci came up with the idea of an under­ground trans­porta­tion route, rather than increas­ing the num­ber of lanes or build­ing anoth­er high­way cut­ting through the heart of Boston.

The project plan of Big Dig was offi­cial­ly start­ed in 1982 and the envi­ron­men­tal assess­ment began in 1983. Con­struc­tion began in 1991 and the offi­cial end date of the project is Decem­ber 31, 2007. The project is owned by Mass­a­chu­setts Turn­pike Author­i­ty, which was cre­at­ed in 1952 to over­see the Turn­pike sys­tem. The main con­trac­tor of Big Dig is Betchel/Parson Brinckerhoff. 

There are oth­er key orga­ni­za­tions involved in this project, as list­ed below:

• Fed­er­al High­way Admin­is­tra­tion (FHWA): with­in the US Depart­ment of Trans­porta­tion, pro­vide gen­er­al over­sight and ensure the expen­di­ture of fed­er­al funds
• The Boston Trans­porta­tion Plan­ning Review (BTPR): re-design and plan the entire high­way and tran­sit sys­tem in Boston
• Mass­a­chu­setts Exec­u­tive Office of Trans­porta­tion and Con­struc­tion (EOTC): role as a state Depart­ment of Trans­porta­tion, over­see statewide planning
• Non-gov­ern­men­tal orga­ni­za­tions: Bridge Design Review Com­mit­tee, Sier­ra Club
• Local envi­ron­men­tal and trans­porta­tion groups: Charles Riv­er Water­shed Asso­ci­a­tion, the Com­mit­tee for Region­al Trans­porta­tion and Cit­i­zens for a Liv­able Charlestown
• Ad-hoc orga­ni­za­tions: the Artery Busi­ness Com­mit­tee and the Boston Cham­ber of Commerce

In gen­er­al, var­i­ous stake­hold­er groups par­tic­i­pat­ed in the project plan­ning process. One orga­ni­za­tion to high­light is the Bridge Design Review Com­mit­tee (BDRC). It’s a com­mit­tee made up of 42 stake­hold­ers from var­i­ous back­grounds with dif­fer­ent inter­ests, knowl­edge and con­cerns. There are lawyers facil­i­tat­ing the whole con­sul­ta­tion process, rep­re­sen­ta­tives from local com­mu­ni­ties, nation­al orga­ni­za­tions and ad-hoc orga­ni­za­tions and pro­fes­sion­al engi­neers offer­ing tech­ni­cal sup­port. The com­mit­tee con­sid­ered sev­er­al pro­pos­als of project con­cep­tu­al design. Even though none of them could sat­is­fy all par­ties involved, these pro­pos­als incor­po­rate dif­fer­ent stake­hold­ers’ inter­ests to a large extent and is a valu­able expe­ri­ence for mega-projects afterwards.

How­ev­er, the con­struc­tion of mega-projects is doomed to be dif­fi­cult and indeed all kinds of prob­lems emerge dur­ing the process. Ini­tial­ly pro­ject­ed to cost $2.5 bil­lion dol­lars, the Big Dig turned out to cost $14.8 bil­lion and the time­line is longer than expect­ed as well. Reflec­tion by Vir­ginia A. Greiman notes that more trans­par­ent orga­ni­za­tion­al, financ­ing and gov­er­nance struc­tures are lack­ing in the project. Besides, shared val­ues should be built among all stake­hold­ers in order for a stronger and more trust­wor­thy relationship.

Regard­less of the long times­pan and exces­sive bud­get, the project turned out to be a suc­cess. Green­land cre­at­ed by the high­way decon­struc­tion becomes pub­lic parks and tree lanes. The noise in the neigh­bor­hood is great­ly reduced. Traf­fic con­ges­tion is alle­vi­at­ed and peo­ple find it more con­ve­nient to go to Logan Air­port. The local shell­fish pop­u­la­tion has increased due to the con­struc­tion of an arti­fi­cial reef in Boston Harbor’s Sculpin Ledge Channel. 

CEE sub­jects: Con­struc­tion Engi­neer­ing and Man­age­ment, Envi­ron­men­tal Pol­i­cy and Sus­tain­able Infra­struc­ture, Trans­porta­tion Engineering

• What do you think of the project plan­ning process and com­mu­ni­ty engage­ment? What aspects are wor­thy of praise and what else needs to be improved?
• Trans­paren­cy was a great con­cern when the project con­tin­ued con­struc­tion. What can we do, as engi­neers, to improve trans­paren­cy to ensure the smooth oper­a­tion of construction?
• What lessons can we learn from this mega project?

• Peer reviewed articles
  • Boston’s Big Dig Project: A Cau­tion­ary Tale
  • The Cen­tral Artery / Third Har­bor Tun­nel Project (‘The Big Dig’)
• Pop­u­lar media/news references
  • Boston’s Big Dig | Extreme Engineering
  • Nation­al Geo­graph­ic MegaS­truc­tures Boston Big Dig Doc­u­men­tary 2016
  • The Big Dig: Learn­ing from a Mega Project
  • Boston Big Dig, Cen­tral Artery / Tun­nel Project, Massachusetts
  • State to Address Declin­ing Con­di­tions in Boston High­way Tunnels
  • The Big Dig: project back­ground — Mass.gov
  • What Lessons Can Be Learned from the Boston Big Dig?
• Books/memoirs
  • “Megapro­ject Man­age­ment: Lessons on Risk and Project Man­age­ment from the Big Dig” by Vir­ginia A. Greiman
  • “Com­plet­ing the ‘Big Dig’ : Man­ag­ing the Final Stages of Boston’s Cen­tral Artery/Tunnel Project”