Promotional literature touting the advantages of overhead wires for electric transmission versus underground conduits that often failed in heavy storms.
Jim Vrabel looks at the history of downtown Boston's busiest intersection. He also discusses the deadly 1897 gas explosion that occurred here during the building of the Tremont Street subway line (4 min).
This 2017 paper from Harvard's Kennedy School of Government "presents rough order-of- magnitude estimates for the capital cost of the North South Rail Link (the “Link”), a proposed infrastructure project to connect the commuter rail and Amtrak lines that currently terminate at Boston’s North and South Stations via underground tunnels."
This video compares the subway system of Boston to that of Paris and finds that the lack of ring lines that connect subway lines to one another makes the MBTA far less efficient (26:30 min).