Green Line Question

[JHB]

Hi!
I was wondering what the blue light on the side of the green line cars mean?
Today I was also on a train that the driver was pushing the tow-mode button the entire ride, what does that do?

[jwhite07]

The blue light indicates some sort of propulsion fault.

[F-line to Dudley via Park]

Sticking this here since it's a Q&A thread. . .


Interesting WBUR explainer article about new measures the T is taking to control the decibel level of wheels squealing through Boylston: http://www.wbur.org/news/2017/05/01/mbta-wheel-squeal" onclick="window.open(this.href);return false;

Just last week T engineers finished putting flange stick lubricators on all the newer model Green Line trains. Imagine a giant Pez dispenser that holds a stick of graphite pressed against a train wheel.

The flange stick lubricators add the graphite to the wheels as they turn, aiming to reduce wear to the wheels and rails, and, at the same time, to reduce that squealing noise the wheels make.

[parovoz]

Which reminds me of a question that I was asking myself 15 tears ago, when I was regularly using the D branch... I heard more than once how at some stops the car (was it a Boeing or K-S? do not remember) would transmit a sequence of digits using, believe it or not, Morse code. Was I hearing things? If not, what was the purpose of those communications?

[jwhite07]

I heard more than once how at some stops the car (was it a Boeing or K-S? do not remember) would transmit a sequence of digits using, believe it or not, Morse code. Was I hearing things? If not, what was the purpose of those communications?

It wasn't the car itself, it was a transmission over the Green Line's radio channel. I was told it was something to do with the requirement to occasionally transmit radio identification. Way back when, you would periodically hear a recorded voice message on the Green Line radio channel announcing "This is KTI 787" (I think it was, anyway). The Morse apparently replaced that recorded voice message as the means of radio ID. Now that the Green Line channel is digital, not sure if that's still a requirement - I don't ride it as much or for as long as I used to, but I haven't noticed any Morse or other radio ID for quite a while.

[CRail]

Police and Fire (etc) channels do the same thing.

[Diverging Route]

Call sign ID requirements can be met in many ways. Note that on the CR, "Keolis 302..." is a valid way to ID the mobile station. If the MBTA GL were to use the same system, I'd expect to hear, "MBTA 3600," but that's not done. So it may be the case that the MBTA has received permission under the exemption, "In those areas where it is shown that no difficulty would be encountered in identifying the transmission of a particular station (as, for example, where stations of one licensee are located in a yard isolated from other radio installations), approval may be given to a request from the licensee for permission to omit the station identification."