Those do not mark chains, they mark surveying stations. A station is 100 feet. Stations tell the distance to a reference point; sometimes a real point, sometimes a fictitious point.
In the old days (until about 8 years ago) the Green Line base point was Lechmere which was station 1000. All distances were measured west from Lechmere. The Fenway portal was at station 1223+00 so it was 22,300 feet from Lechmere. These were done with black letters on white and usually faced the track. Many still exist. (If you're waiting for a C train at Park Street, station 1098 is on the wall in front of you)
Today, they use a new system. The markers are usually perpendicular to tracks so there is writing on both sides. The lettering is in the color of the line (e.g. blue, orange, etc.). So, for example, "CE078+00" in green at Coolidge Corner, means the C line, eastbound, station 78. B & C tracks are measured westbound from Kenmore Junction. D tracks are measured from Beacon Junction. E tracks are measured westbound from Copley Junction (as far as Brigham Circle). Kenmore to Lechmere are measured eastbound with zero at Kenmore junction. Somewhere between GovCen and Haymarket, there is a 130 foot "adjustment" to the northbound survey markers because the northbound route is about 130 feet longer. How this is accounted for is unknown.
Survey station signs are usually two letters (R=RedLine, O=Orange, E=Heath). The 2nd letter is the direction of travel (W, E, N, S), thence three numbers measuring the distance, sometimes followed by "+00" or ".nn".
The painting on the "new" signs is fading fast. Just about all on the "B" line are unreadable, despite being less than 10 years old. See the photo below which shows both old and new. In addition, on the Riverside line, I've seen several markers that (I believe) mark the old B&A Highland Branch with the distance to the main-line junction now at/near Yawkey Station. For example, at Waban, there is "new" marker "DE422+00" (42,200 feet to Beacon Junction) next to old marker "1638" (63,800 feet to Lechmere) next to very-old marker "428" (42,800 feet to Yawkey).
In the old days (until about 8 years ago) the Green Line base point was Lechmere which was station 1000. All distances were measured west from Lechmere. The Fenway portal was at station 1223+00 so it was 22,300 feet from Lechmere. These were done with black letters on white and usually faced the track. Many still exist. (If you're waiting for a C train at Park Street, station 1098 is on the wall in front of you)
Today, they use a new system. The markers are usually perpendicular to tracks so there is writing on both sides. The lettering is in the color of the line (e.g. blue, orange, etc.). So, for example, "CE078+00" in green at Coolidge Corner, means the C line, eastbound, station 78. B & C tracks are measured westbound from Kenmore Junction. D tracks are measured from Beacon Junction. E tracks are measured westbound from Copley Junction (as far as Brigham Circle). Kenmore to Lechmere are measured eastbound with zero at Kenmore junction. Somewhere between GovCen and Haymarket, there is a 130 foot "adjustment" to the northbound survey markers because the northbound route is about 130 feet longer. How this is accounted for is unknown.
Survey station signs are usually two letters (R=RedLine, O=Orange, E=Heath). The 2nd letter is the direction of travel (W, E, N, S), thence three numbers measuring the distance, sometimes followed by "+00" or ".nn".
The painting on the "new" signs is fading fast. Just about all on the "B" line are unreadable, despite being less than 10 years old. See the photo below which shows both old and new. In addition, on the Riverside line, I've seen several markers that (I believe) mark the old B&A Highland Branch with the distance to the main-line junction now at/near Yawkey Station. For example, at Waban, there is "new" marker "DE422+00" (42,200 feet to Beacon Junction) next to old marker "1638" (63,800 feet to Lechmere) next to very-old marker "428" (42,800 feet to Yawkey).
Attachments:
0_Survey2.jpg (44 KiB) Viewed 1755 times
Attachments:
(17.64 KiB) Downloaded 1699 times
(30.23 KiB) Downloaded 1699 times
