MBTA Commuter Rail (Operations, Keolis, & Short Term)

whighlander

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Providence is probably going to eventually glom off of Amtrak's high-bandwidth WiFi it's installing up and down the NEC. The catenary towers make a naturally great amplifier for focusing the signal, so they're able to draw out their signal strength linearly within the trackbed instead of wasting it in an all-around radius. The system they're using is specialized like that for narrow-but-linear transmission range.

The other lines...yes, something way better is needed. Although a justifiable reason for persisting this long on the take-it-or-leave-it gratis service is that the tower installations needed for broadcasting decent onboard WiFi of their own wouldn't come until Positive Train Control installation was substantially complete across the system. Now they've got those new towers erected for the PTC signals' radio spectrum and all those new telephone poles to carry the fiber cable to the towers. Once they're safely past the PTC deadline they've got a ready-made solution for mounting the WiFi transmitters that would form the basis of much more robust network than they've had to-date.
All -- a lot of what you are talking about is a temporary situation as personal communications technology is making a revolutionary transition to a highly dynamic network.

As 5G is deployed in the next few years -- the different technologies, different frequencies, etc. used by different devices -- will disappear into the background [at least in the urban / suburban areas] -- [not talking about rural Montana or most of Alaska]. Your personal device [smart phone, tablet, watch, etc.] will:
  1. Negotiate with the available network infrastructure for service
  2. Connect you with enormous instantaneous bandwidth do the task required
  3. Provide the access to up / down load / talk / transmit live video, etc. -- using a very short intense burst of connectivity
  4. Disconnect from you and go into a mode waiting for the next customer.
    1. which could be you if you are chatting and sharing video with someone

You will never know how the connection was made to what part of the infrastructure and you wont care.

The relevant technical terms are: low latency, wide instantaneous bandwidth, polarization, angular, code and frequency diversity and multiplexing
 

bakgwailo

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^ Most likely, not. It will be evolutionary over 4G and wireless companies will continue to limit things like tethering, and it will take years to fully get rolled out and get consumers onto upgraded phones that support 5G. WiFi isn't going anywhere and will still be a draw for people. Not to mention things like AT&T's "5G+" that is rolling out is... fake 5G, just like a lot of the 4G rollout (looks at TMobile) when it first started.
 

stefal

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5G service will also be more spotty along the commuter rail lines, unless the T does something about it, which will cost tons of money, likely equivalent to working wifi costs. There are several swaths of dead spots that render my phone useless on the Lowell Line, and that's with 4G/3G. 5G has lower frequencies and will need far more "cells." It's why both the fake and real versions are being tested in cities where they can attach the cells every 100-250 meters on telephone poles, light posts, and caternary poles, reaching and serving say a few thousand people and not suburban or rural areas where the same practice will maybe reach up to only say 100 people, or along a commuter rail line that will serve 100 people every 20-60 minutes if that.
 

HelloBostonHi

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5G service will also be more spotty along the commuter rail lines, unless the T does something about it, which will cost tons of money, likely equivalent to working wifi costs. There are several swaths of dead spots that render my phone useless on the Lowell Line, and that's with 4G/3G. 5G has lower frequencies and will need far more "cells." It's why both the fake and real versions are being tested in cities where they can attach the cells every 100-250 meters on telephone poles, light posts, and caternary poles, reaching and serving say a few thousand people and not suburban or rural areas where the same practice will maybe reach up to only say 100 people, or along a commuter rail line that will serve 100 people every 20-60 minutes if that.
There are two "varieties" of 5G, and the one TMobile has been working on (low band 5G) will likely offer gains on commuter rail.
 

whighlander

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5G service will also be more spotty along the commuter rail lines, unless the T does something about it, which will cost tons of money, likely equivalent to working wifi costs. There are several swaths of dead spots that render my phone useless on the Lowell Line, and that's with 4G/3G. 5G has lower frequencies and will need far more "cells." It's why both the fake and real versions are being tested in cities where they can attach the cells every 100-250 meters on telephone poles, light posts, and caternary poles, reaching and serving say a few thousand people and not suburban or rural areas where the same practice will maybe reach up to only say 100 people, or along a commuter rail line that will serve 100 people every 20-60 minutes if that.
Stefal -- I think you need to do more reading about 5G
It is true that 5G will be more personal so the cells will be smaller and more frequent. That actually works well for rail lines getting coverage early in Urban/ dense suburban areas as there are plenty of places to put antennas and the associated electronics and its easy to get the use of the ROW for installation of the background infrastructure such as the fiber optic cables used to connect the cells sites ["Backhaul"]

As to frequencies -- there will be a number of frequencies used depending on deployment and terminal considerations -- some of the frequencies will be much higher than are currently used for personal communications and some will be the TV frequencies currently being vacated [see the "need to rescan" if you don't have cable]

Finally

This is Christmas Eve -- Merry Christmas*1 to everyone on ABForum

Peace to all

We can resume the discussion later



🔔 🎄 🔔



*1

Happy Chanukkah

or if you chose to celebrate any other or any Winter Solsticial Commemorative Event -- then felicitous greeting for your celebrations in the appropriate manner for your culture [whether native or adopted]
 

stefal

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Perhaps I didn't consider the fact that the trains themselves can host rooftop antennas. In that case, they will likely work just fine for high speed service.

That actually works well for rail lines getting coverage early in Urban/ dense suburban areas as there are plenty of places to put antennas and the associated electronics
That is what I said. Urban areas work great. That's why the companies initiating 5G are doing it in cities. In terms of rail line coverage, you can certainly get a lot of people (not even those riding the train, mostly those living/working in the area) covered with a single antenna device, especially on the green line, parts of the blue line, and select bus routes where there are already catenary poles ready to host infrastructure. Where there aren't catenary poles, companies are replacing current light posts with 5G-ready antennas. But on the commuter rail, which is what we are discussing, venturing out past Zone 2 it starts to get exponentially harder to effectively/realistically (financially sensibly) cover as many people with the same amount of antennas. That's where we'll need existing infrastructure (towers) to get updated for 5G and install rooftop antennas on CR cars.

and its easy to get the use of the ROW for installation of the background infrastructure such as the fiber optic cables used to connect the cells sites ["Backhaul"]
No, its not. That is the hardest part.
 

JeffDowntown

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Perhaps I didn't consider the fact that the trains themselves can host rooftop antennas. In that case, they will likely work just fine for high speed service.



That is what I said. Urban areas work great. That's why the companies initiating 5G are doing it in cities. In terms of rail line coverage, you can certainly get a lot of people (not even those riding the train, mostly those living/working in the area) covered with a single antenna device, especially on the green line, parts of the blue line, and select bus routes where there are already catenary poles ready to host infrastructure. Where there aren't catenary poles, companies are replacing current light posts with 5G-ready antennas. But on the commuter rail, which is what we are discussing, venturing out past Zone 2 it starts to get exponentially harder to effectively/realistically (financially sensibly) cover as many people with the same amount of antennas. That's where we'll need existing infrastructure (towers) to get updated for 5G and install rooftop antennas on CR cars.



No, its not. That is the hardest part.
The other thing to bear in mind is that the mmWave service for 5G requires a lot of antennas because transmission distance is short (and blockage from things like foliage is severe) . In Boston Verizon has been siting antennas for 5G virtually one per block. That is a lot of expense for a commuter rail line.
 

Riverside

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According to WCVB, officials are blaming a worker, saying "a switch wasn't set properly".
 

jklo

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MBTA says on the website that the derailment caused damage to one of the tracks. Can still get by but only one track is available. That's going to cause lots of delays, even on a Friday.
 

cubalibre

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This makes at least six(?) significant derailments for the MBTA this year? Maybe there’s a disgruntled commuter’s blog out there who tracks this.

Edit: not broken down for 2019, but over the past five years there have been 43 derailments across the whole system.
 
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F-Line to Dudley

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This makes at least six(?) significant derailments for the MBTA this year? Maybe there’s a disgruntled commuter’s blog out there who tracks this.

Edit: not broken down for 2019, but over the past five years there have been 43 derailments across the whole system.
Reporting is separate for commuter rail and rapid transit because of FRA vs. non-FRA oversight. The worrisome stats were for rapid transit only, though the 43 tally is inflated vs. other systems because the T counts derailments of maintenance vehicles like hi-rail pickup trucks (which have an inherently higher derailment rate than rail-only vehicles), while other systems only counted derailments of the primary fleets during revenue + non-revenue moves. Without reporting parity it's hard to compare "bad" vs. "really bad".


Commuter rail hasn't had nearly as many, for sure, and most of them were probably during yard moves. It's kind of hard to split the switch nearest to Yawkey/Landsdowne because that's inside cab signal territory and there should've been auto-detection of the fault with automatic brake application preventing the train from even getting close to the switch. Either the signal system is at fault, or the engineer went into manual override at sub- 10 MPH (as you're allowed to do) and blew through a warning. Otherwise there's normally ample prevention for this type of scenario.
 

tysmith95

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Commuter rail hasn't had nearly as many, for sure, and most of them were probably during yard moves. It's kind of hard to split the switch nearest to Yawkey/Landsdowne because that's inside cab signal territory and there should've been auto-detection of the fault with automatic brake application preventing the train from even getting close to the switch. Either the signal system is at fault, or the engineer went into manual override at sub- 10 MPH (as you're allowed to do) and blew through a warning. Otherwise there's normally ample prevention for this type of scenario.
There was one near south station a few months ago from 2 trains bumping into each other, a Rockport train derailed earlier this year near Sullivan due to an failure in an engine, a Fitchburg train derailed at fairly high speed last year due to a wheel separation.
 

GP40MC

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Last night's incident appears to have started as a switch failure (probably one end of the crossover). C&S probably not on the scene as yet, so the crew would've been instructed to check and line the route for their move. This means taking the entire crossover off-power and hand-throwing the switches - leaving the power off. After that is done, then the dispatcher would give a Rule 241 - permission to pass the stop signal. Various things that could go wrong include only lining one end of the crossover, putting the power back on (which might actually cause the switch to go back to its "failure" position) among a laundry list of causes.
 

F-Line to Dudley

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Last night's incident appears to have started as a switch failure (probably one end of the crossover). C&S probably not on the scene as yet, so the crew would've been instructed to check and line the route for their move. This means taking the entire crossover off-power and hand-throwing the switches - leaving the power off. After that is done, then the dispatcher would give a Rule 241 - permission to pass the stop signal. Various things that could go wrong include only lining one end of the crossover, putting the power back on (which might actually cause the switch to go back to its "failure" position) among a laundry list of causes.
Icing issue at the switch, perhaps?
 

GP40MC

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There's a myriad of things that could cause a switch failure including ice in the points: Signal code failure, a relay failure, debris (other than snow/ice) in the points., point detector out of adjustment,
switch out of adjustment...

Based on what I just saw/heard on Channel 4 just now, it sounds like either one half of the crossover was not lined for the move or maybe put back on power after it was thrown by hand, thus flipping back as I described in the original post.
 

whighlander

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The other thing to bear in mind is that the mmWave service for 5G requires a lot of antennas because transmission distance is short (and blockage from things like foliage is severe) . In Boston Verizon has been siting antennas for 5G virtually one per block. That is a lot of expense for a commuter rail line.
JeffD -- Siting of 5G antennas involves a lot of factors -- so the answer to the question of siting is a book-length report not a couple of lines

Among other things the available height of an antenna makes a significant difference particularly for the 5G mmwave service as unless you have a really nice reflecting surface such as a old warehouse with galvanized metal walls -- everything is direct line of sight with minimal penetration through most structures

If you are in the midst of 3 Deckers and all you can do is put an antenna on a lightpole of Telephone Pole [about even with the rooflne of the 3 Decker] you can only see and connect with the houses on either side of the street -- the next street over is going to have connectivity which is erratic at best

On the other hand if you can put up a tall pole [say 50 to 75 feet high] along a stretch of the Commuter Rail ROW behind some older low [1 story or so] Industrial buildings where there will be less NIMBYist resistance -- you have the advantage of much greater coverage from above as the power levels are sufficient to reach out to at least 0.5km with good data handling characteristics @ 28 GHz *1

The important number from the table obtained from the paper is that @ 28 GHz you can achieve quite effective data transmission [3 GHz from the Cel Site and 0.3GHz back to the Cel Site from your modem at home or on the train] @ an operating distance of 0.5 km [Note that the model used to generate the table makes specific assumptions about foliage, atmospheric and weather and other losses outside of the 1/r^2 loss]

*1
Millimeter-Wave Communications: Physical Channel Models, Design Considerations, Antenna Constructions and Link-Budget
Ibrahim A. Hemadeh, Member, IEEE, Katla Satyanarayana, Student Member, IEEE, Mohammed El-Hajjar, Senior Member, IEEE, and Lajos Hanzo, Fellow, IEEE

Article in IEEE Communications Surveys & Tutorials · December 2017 DOI: 10.5258/SOTON/D0344

Link Budget
Downlink Uplink
Transmit power (dBm) 40.00 20.00
Transmit antenna gain (dBi) 25.00 17.00
Carrier frequency (GHz) 28.00 28.00
Distance (km) 0.5 0.5
Free space propagation loss (dB) 115.32 115.32
Other losses (shadowing, fading) 20.00 20.00
Receive antenna gain (dBi) 12.00 25.00
Received power (dBm) -58.32 -73.12
Bandwidth (GHz) 0.50 0.5
Thermal noise (PSD) (dBm/Hz) -174.00 -174.00
Noise figure 7 7
Thermal noise (dBm) -80.01 -80.01
SNR (dB) 21.69 6.89
Implementation loss (dB) 6.00 6.00
Spectral efficiency 6.20 1.2
Data rate (Gbps) 3.1 0.6
 

F-Line to Dudley

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OK...so, summarizing without the listicles:


The pretty tall towers the T installed for Positive Train Control and ran all that fiber cable out to: they make good WiFi and/or 5G mounts.

Which is probably exactly what they planned to do from the beginning, since pole real estate fetches reliable $$$ from telco companies who rent out mounts next to all the mission-critical public service stuff on the pole.

And this is all a generally agreed-upon good thing, we think.
 

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