The EGE wrote:Heavy rail was never a plausible option, for engineering reasons. A Blue Line extension was considered and rejected early in the alternatives; it would have been costlier to add a new tunnel under the Charles for no additional benefit.
An Orange Line branch would have been even worse. It would have halved frequencies from Community College north (a very big deal), cost more to build (heavier bridges, longer stations, etc), and also required a new Charles tunnel. The Green Line takes a tightly curved and very steep path to get from North Station to the viaduct; I don't believe you could run Orange Line stock in regular service on it. Orange Line trains may also be too heavy for the Lechmere viaduct. The Orange Line could not have possibly supported branches to both Medford and Union Square; in order to serve both, it would have required a tunnel under Winter Hill (an alternative rejected for the Green Line as being much more expensive). Additionally, using the Orange Line would have eliminated any chance of potential Green Line flanks to Porter, Sullivan/Everett, or the Grand Junction.
sery2831 wrote:This is not a GLX thread... lets get back to CBTC discussion.
jonnhrr wrote:Unless they are looking at it as a test bed for CBTC in the Central Subway which makes sense.
jonnhrr wrote:Given that the touted advantage of CBTC is to squeeze more TPH out of a line (whether it actually does this is another issue) wouldn't the T be better off just installing a conventional low-tech signaling system, something proven? After all TPH is not an issue on this line, it has more than enough capacity for the traffic.
Unless they are looking at it as a test bed for CBTC in the Central Subway which makes sense.
Jon
F-line to Dudley via Park wrote:-- A return to 50 MPH speeds on the D, and an expansion of 50 MPH territory to more places on the D and certain places on GLX.
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