►1990 The state commits to completing the Green Line extension project by 2011, after the Conservation Law Foundation threatens to block the Big Dig. The organization says Somerville and Medford need the project because the communities will suffer environmental impacts from the massive highway project.
►2005 The Conservation Law Foundation files suit, saying the state is reneging on its environmental commitments, including the Green Line extension. The state agrees to finish the project by 2014, in order to settle the suit.
►2007 Governor Deval Patrick says he wants to pursue federal funding that would pay for a large chunk of the project.
►2010 A Department of Environmental Protection report shows that the project could be delayed further, into 2015.
►2013 The state begins construction work on early aspects of the project, such as widening bridges and demolishing MBTA facilities in Cambridge to make way for the project.
►2014 Officials agree to make a paved trail for bikers and walkers part of the project, running along the extension. The state also submits its final application for a federal grant that could fund up to half of the project.
►2015 The federal government makes its funding official for the project. But as soon as contract negotiations begin on one of the largest portions of the project, the MBTA and the construction firm it has hired cannot come to an agreement on a price. The MBTA’s fiscal control board halts new work on the project.
►2016 The MBTA’s fiscal control board and the Massachusetts Department of Transportation board on Monday will receive a report on a dramatically slimmed down version of the project. Ultimately they will decide whether to pursue that plan or pull the plug.Nicole Dungca can be reached at email@example.com. Follow her on Twitter @ndungca.