The Indigo Line is actually the Fairmount Bbranch of the commuter rail that runs from South Station to Readville in Hyde Park. It only makes 5 stops, but it runs through a very densely populated area of Boston and Dorchester.
The MBTA and local community groups have decided to upgrade the CR service and add more stops. This is where it gets interesting. Some people want the line to be fully
converted to Rapid Transit while others (mainly the MBTA) want it to be just CR with more stops and more frequent trips.
Construction of Phase 1 of the "Indigo Line" is under construction now. This will rebuild Uphams Corner and Morton St stations so they are ADA compliant, high level platforms, and better shelter from the elements. Phase 2 will construct new stations along the route at Newmarket, Five Corners, Talbot Ave, and Blue Hill Ave. I propose adding two more at Columbia Rd and River St. What will be interesting is what type of rolling stock is used. This stretch of track is too valuable to be completely converted to rapid transit as it is
the only other alternative route into Boston from the south west (the other being the rail along the Southwest Corridor/Amtrak/Orange Line.) Standard commuter rail engines are not that good at stopping and starting at close intervals so the best two options are to electrify the line and run electric commuter trains or a new technology called Diesel Multiple Units (DMU). The idea is that each car will have its own diesel engine instead of one large engine pulling the entire train. This would work well for short distances that require many stops and starts. Think a trolley but with a diesel engine instead of over head wires.
Route 128 and Dedham
I think that the current proposal isn’t enough. At the very least the line should be extended to Route 128 where it would connect to commuter rail to Providence and Amtrak to New York. It would also add better transit to a new development adjacent to the station.A second line should head to Dedham along an abandoned spur from Readville to Dedham center with 2 or 3 stations.
West Medford and Woburn
Currently there are only proposals to extend either the Blue Line or the Green Line to West Medford. While one of these, preferably the Green Line, is bound to be constructed, my idea is for the Indigo Line to serve this route. This all depends on one thing first, the North-South Rail link. This would link the commuter rail lines from the north to the ones coming from the south. This is probably one of the best ideas for transportation, not just in Boston, but in the entire northeast. The problem is that we just built a tunnel for cars in the exact same spot where the rail tunnel will go, and that cost $14.6 billion. The NS Rail link is supposed to travel under the highway tunnel from Back Bay and South Station to just past North Station. If this was to be constructed, the Indigo Line could become a full, real, rapid transit, subway line.
The tunnel to be built would go under the highway and therefore under all the other subway lines. The Boston stops would be South Station, Aquarium, and North Station. The Indigo Line tracks would run parallel on the outside of two commuter rail tracks. Because the Indigo Line would be using existing commuter rail stock or new DMUs, the out tracks could be used for commuter rail if needed.
The current proposal to extend the Green/Blue Line to West Medford is fine but I think that an extension through Winchester to Woburn Center (and then maybe to Route 128). The stations would remain the same but after Winchester Center the line would follow an abandoned ROW into Woburn Center. Due to a constrained ROW in Winchester center and development on the abandoned ROW in Woburn, this extension would be expensive but would allow the reconstruction of old bridges and allow a much better connection for the people of Woburn to the Boston area.