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| Re: PHOTOS: MBTA MPXpress Locomotive #010 In Delivery (1024595) | |||
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Re: PHOTOS: MBTA MPXpress Locomotive #010 In Delivery |
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Posted by aem7ac on Wed Jan 12 01:24:51 2011, in response to Re: PHOTOS: MBTA MPXpress Locomotive #010 In Delivery, posted by AEM-7AC #901 on Wed Jan 12 01:14:31 2011. The problem is that in the United States, the choice ends up being between the Red Line at 45 mph MAS and direct access to downtown, and a EMD-powered diesel locomotive with higher MAS, but awful acceleration performance with a terminal at some out of the way place.Since when was South Station Boston a out-of-the-way place? In commuter rail core cities, terminals are basically within 0.5 mile of downtown. This is true in Boston, New York (Penn and GCT), Philadelphia, Washington D.C., Chicago, and San Francisco. Terminals that aren't downtown leads to cities that aren't real commuter rail cities (e.g. Baltimore). As for the 45 mph MAS, I'd like you to plot a speed profile for one typical line on the MBTA network (pick any of them -- Greenbush, Kingston/Plymouth, Readville, Franklin, Needham -- just not the Providence Line). See how many percent of the time the train really spends cruising at more than 45 mph. The commuter rail experience on British Rail was that except for express services that skip the inner urban zones, acceleration is far more important than MAS. This influenced the decision to design the Networkers for a 75 mph MAS (compared to 90/100 mph MAS that was the standard on most of the network). So to make a half-assed example, I'd probably be content with MBTA if they ran some service from one side of Rt 128 to the other via the Washington Street tunnel without building some specialized and separate tracks. Why would you ever do this? The demand density outside Route 128 tapers off pretty quickly. So right now Orange Line runs something like an every-12 minute service in the off-peak hours, whereas on most of the Southside commuter rail lines off-peak service is less-than-hourly. If we were really going to join the service together, you'd have to take an average -- just so that you aren't carrying air by the time you hit Route 128 -- so you'd sanction every 30 minute daytime service on the Orange Line, with every other train turned at Route 128 because there simply isn't enough demand beyond that station? |
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