the real use of the north south rail link

[totient]

Buried in this article is a bombshell of a lede: there is a regulatory limit on how fast a locomotive can switch "ends" from inbound to outbound and this is by far the limiting factor on operations at Boston's two terminal stations. Through running trains are not subject to this timing constraint and can make several times more efficient use of available station tracks. Four through tracks at South Station, even if they were conversions of existing tracks, would do much more to improve capacity there than the currently-planned expansion from 13 dead-end tracks to 20.

Our current state Governor has a strongly suburban base that would greatly benefit from improved operational efficiency at South Station. I can only imagine he doesn't know -- as I didn't -- how much more impact the North South Rail Link would have; it's really the only explanation for his advocacy of the South Station expansion.

Comments

[paradoox]

So, this quote appears to be what you are talking about: "(Railroad regulations require crews to perform a brake test when changing ends in this manner, which can take several minutes.)"

However, I should point out that at least at South Station the MBTA locomotives don't actually switch ends. They always push into South Station and pull out of South Station.

[totient]

"Changing ends" means exactly what you describe: the train consist is the same, in the same order, but going the other direction. This requires a type III brake test to be performed. I know that sounds crazy, but why else would the T need to expand from 11 to 18 tracks at South Station when they're only serving 18 trains an hour?

[drwex]

That's whacky. Interesting find.

[totient]

What's extra wacky is the T would still use the Somerville and South Boston yards for storing trains between morning and evening rush -- but they'd use Somerville for the South Shore lines, and South Boston for the North Shore lines.

[i_leonardo]

whoa! that seems so obvious now that it's been pointed out.