Milepost Prefixes

I started hearing MBTA using prefixes for their mileposts on the radio.

Here are the ones I know right now:
Providence Line - AM
Worcester Line - BL
Needham Line - NB
Fairmount Line - FB
Franklin Line - DB
Fitchburg Line - BF
Haverhill Line - BV (south of Everett Junction) WR (north of Everett Junction)
Lowell Line - BW
Newburyport/Rockport Line - BV (south of Everett Junction) BE (Everett Junction to Newburyport) GB (Beverly to Rockport)
Grand Junction Branch - GJ

Anybody know the prefixes for the old colony lines?

I'd like to know what (if anything) those prefixes mean and where they came from. Just looking at the list, they seem pretty random.

Some uninformed guesses:
"BE" for Boston East
"BW" for Boston West
"WR" for Western Route
"BF" for Boston Fitchburg
The others? Dunno.

Haven't heard them, but "BeeEee," "BeeGee," and "BeeVee" can sure sound the same on a radio in a high-noise environment, although the MP numbers would be a distinguisher.

GB= Gloucester-Beverly?
BV=Boston eVerett?
BE=Boston-Eastern Division?

What was the usage before? I assume Amtrak is still dispatching the Providence line, if so then Amtrak & MBTA would have to agree. AM would be Attleboro something I would think, then there would have to be designations in RI. GJ is obvious. BL - could that be Boston Line?

They are a mix of either the Line Prefix, or the PTC induced milepost designation for each line. The prefix of B was to denote the milepost form Boston, yet a large exception remains from that logic.

Milepost Prefix
BY - Boston North Terminal
BE - Eastern Route
BF - Fitchburg Route
BG - Gloucester Branch
BH - New Hampshire Route
BW - Western Route
BC - Wildcat Branch

BD - Dorchester Branch
BK - Franlin Branch
BB - Greenbush Branch
BQ - Kingston Branch
BM - Middleboro Main Line
BN - Needham Branch
BP - Plymouth Branch
BT - Stoughton Branch
BL - Worcester Main Line

Line Abbreviations
BNT Boston North Terminal District
ER Eastern Route
FR Fitchburg Route
GB Gloucester Branch
NHR New Hampshire Branch
WB Wildcat Branch
WR Western Route

DB Dorchester Branch
FB Franklin Branch
GRB Greenbush Branch
KB Kingston Branch
MM Middleboro Main Line
NB Needham Branch
PB Plymouth Branch
SB Stoughton Branch
WML Worcester Main Line

nomis wrote: ↑Mon Apr 27, 2020 5:47 am They are a mix of either the Line Prefix, or the PTC induced milepost designation for each line. The prefix of B was to denote the milepost form Boston, yet a large exception remains from that logic.

The exception is the Dorchester Branch, which is in mileage from NYC like the Corridor is. I don't believe Amtrak uses any mileage prefixes on the NEC.

By the way these were not PTC induced. It's good practice. When you have the same dispatcher issue something at MP 15 on two different lines in close proximity it can be confusing. Pan Am has been using mileage prefixes for years for everything not on their standard 'Keag mileage chain. The change just happened around the same time PTC was introduced.

What would the milepost prefix have been for the Marblehead Branch? I see BM was used for Middleboro Mainline

BV is Boston Valley. Worcester was Conrail's Boston Line.

So, what's the Grand Junction Milepost Prefix?

The Grand Junction is a Running Track so is self-identified and does not have/need any milepost prefixes. The prefixes only apply to what is consider Main Track or Controlled Siding.

Trinnau wrote: ↑Mon Apr 27, 2020 8:34 am

nomis wrote: ↑Mon Apr 27, 2020 5:47 am They are a mix of either the Line Prefix, or the PTC induced milepost designation for each line. The prefix of B was to denote the milepost form Boston, yet a large exception remains from that logic.

The exception is the Dorchester Branch, which is in mileage from NYC like the Corridor is. I don't believe Amtrak uses any mileage prefixes on the NEC.

By the way these were not PTC induced. It's good practice. When you have the same dispatcher issue something at MP 15 on two different lines in close proximity it can be confusing. Pan Am has been using mileage prefixes for years for everything not on their standard 'Keag mileage chain. The change just happened around the same time PTC was introduced.

Actually, the MBTA mileposts on the Dorchester Branch were renumbered to start from Boston a few years ago. Amtrak doesn't necessarily respect them in the NEC timetable, but all of the bridges/crossings were redone to start from MP 0 at South Station as of at least 2016 , based on the MBTA track chart I have.

Joshua

RenegadeMonster wrote: ↑Mon Apr 27, 2020 9:10 am What would the milepost prefix have been for the Marblehead Branch? I see BM was used for Middleboro Mainline

Back when the Swampscott -Marblehead Branch existed (up until the late 1950s), the Boston & Maine numbered Eastern Route mileposts from North Station with a "B" prefix, and I suspect that carried over to the branch. But since I was in my single-digit years back then I won't swear to that.

B&M Track Charts available from nmro.org show a 'P' prefix on Eastern Route automatic signal designations, e.g. 'P85' for the eastbound stagger block at Pines River. Western Route used a 'D' prefix, apparently for 'Dover' vs. 'Portsmouth'. Updates on these charts go to perhaps 1965, but I believe those prefixes remained in use at least through the end of B&M commuter operation in the mid-80s. The B&M didn't apply prefixes to NH or Fitchburg Division signals, and they remained without prefixes at least through 2010.