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alligator412 t1_j938i2n wrote

Just curious, why is it safe to cross the tracks on the park street station? I assume those are protected somehow?

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andr_wr t1_j9390lp wrote

There's no third rail on the Green Liner - it's overhead power.

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Trpdoc t1_j93lgs9 wrote

What the hell does 3rd rail mean. Everyone talks about it like it’s so obvious

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enyopax t1_j93ln6z wrote

It's a live rail, meaning it has an electrical current running through it. It's what powers most subways. There is usually a plate that contacts it from the train but if you accidentally (or purposely) touch it, it will light you up.

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75footubi t1_j93qj5k wrote

Fun Fact: the third rail on the Boston systems (red, blue, orange) almost always don't have covers. This is not something that's a part of their design standards. On every other subway system I've done work for, they at least attempt to keep covers on the third rail.

As someone who's worked as a consultant/contractor for several different transit and rail agencies, MBTA's approach to ontrack safety is downright terrifying.

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TiredCr0codile t1_j93vsvs wrote

What's the deal with no covers? Does it require retrofitting the train?

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75footubi t1_j93w7wk wrote

I don't know the exact details of why MBTA doesn't have them, but in the other systems I've worked for, the little paddle on the rail car that contacts the third rail does it on the underside, so a cover doesn't interfere with that

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TiredCr0codile t1_j943ho9 wrote

The MBTA is probably the poorest run govt agency I've encountered so far.

3rd rail incidents on MBTA are pretty rare however. If someone illegally enters right of way and falls on one, that's on them.

They typically de-energize whenever contractors need to work on ROW.

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75footubi t1_j94ds7e wrote

>They typically de-energize whenever contractors need to work on ROW.

The procedures/"lock out/tag out" process, at least from the contractor POV seems very loosey goosey and there's a lot less emphasis on exclusive track occupancy and defined on track protection methods than I'm used to.

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TiredCr0codile t1_j94rv77 wrote

I don't even know what their lockout tagout procedure is. Whenever I work out there I work as if it's live

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75footubi t1_j95ect8 wrote

Yeah, always work as if it's live, but still, when you're on a hirail vehicle, not being 100% certain that another train isn't going to come on to your track is terrifying

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SilentButtDeadlies t1_j95tikq wrote

They deenergize it for non revenue hours service I think, but you still are supposed to act like it's live otherwise you get in a bad habit. Most of the work I've done was during revenue service so it was active. I've met some people who have touched it and lived.

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TiredCr0codile t1_j95z0ar wrote

Due to staffing, it's pretty tough to get access during ROW these days

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SilentButtDeadlies t1_j9628xv wrote

Yeah, I don't work on mbta projects anymore thank God, but we had several projects get cancelled around the time of the orange line shutdown due to all the staffing shortages.

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Bald_Sasquach t1_j965yop wrote

I would guess so actually. I haven't looked for the contact pads on the orange or red lines but you can easily see the blue line's plates rubbing along the top of the third rail, sparking every now and then. They stick down and out from the train so yeah a cover would be in their way.

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AccomplishedGrab6415 t1_j96mk75 wrote

"pickup shoes" as they're called use the top of the 3rd rail on all of our heavy rail lines.

Blue of course only uses 3rd rail between downtown and Bowdoin. It switches to overhead catenary at airport.

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hannahbay t1_j943kw1 wrote

I didn't even know you could cover those, seems like it would be a no-brainer for safety?

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75footubi t1_j94efwy wrote

It's less about rider safety and more about trackside worker safety. Even platform barriers are more about protecting the train drivers from the trauma of someone stepping out in front in a suicide attempt than protecting riders from doing so.

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AccomplishedGrab6415 t1_j96mw0j wrote

It's one more thing they'd have to maintain and reinstall when doing track work. I've heard stories from the inside about parts being deliberately left off trains after being repaired that don't risk safety or operation, but will protect the mechanicals from premature failure and weather corrosion. I'm told they leave them off because "it's easier."

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Tedroe77 t1_j93q43v wrote

Or pee on it. Don’t pee on it either.

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GtrMike20 t1_j93sy4x wrote

🎵 Don’t whizz on the electric rail! 🎶

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TiredCr0codile t1_j93vy8u wrote

You could walk on it as long as you don't have one foot on the ground and jump onto it (not recommended) haha

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andr_wr t1_j93qu04 wrote

Subway trains get electric power from an electrified rail or line placed somewhere in the tunnel. Many trains get power from a third rail because they run inside short/small tunnels. Other trains get their electricity from an overhead power rail or power line because the tunnels are taller/larger.

The third rail is a rail that is usually built next to and higher than the two rails that support the train's wheels. The third rail will be on one side of the train but doesn't always stay on the same side of a train. Typically at stations, the third rail is farthest from the platform.

No matter if a train gets its power from a third rail or from an overhead wire, most subway train's get about 600 volt direct current electricity. Some subway lines have lower voltage power and others slightly higher. Because of this high voltage it is very dangerous. (For reference, car batteries are 12 volts, for example.)

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Trpdoc t1_j93yj3f wrote

Ding ding ding best answer!!

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wcruse92 t1_j93lnn9 wrote

It's the rail that powers the train.

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Trpdoc t1_j93mgwv wrote

Seems kind of unnecessary, like why can’t they just hide it

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trowdatawhey t1_j93mzof wrote

It is hidden after the 2nd rail. You didnt even know where it was until now

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Trpdoc t1_j93nb2f wrote

Didn’t even know there was a second rail!

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NotAHost t1_j93s2rj wrote

Did you think all trains were unicycles or something?

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Trpdoc t1_j93ytzl wrote

Nah bro thought the mice biking were powering it!

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Justtryme90 t1_j93x1rw wrote

I mean.. there are two tracks... those are rails.

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Trpdoc t1_j93ywni wrote

That all sounds like 1 rail where I come from

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Justtryme90 t1_j941hrv wrote

Do you come from somewhere other than earth....?

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dogs-and-snacks t1_j93p4d6 wrote

They do hide it that’s why up until an hour ago you didn’t know what or where it was

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bakgwailo t1_j93nt46 wrote

It's fairly obvious to anyone who uses a subway.

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Trpdoc t1_j93o3i2 wrote

Used a subway for 5 years had no clue

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bakgwailo t1_j93q37g wrote

I mean you never noticed all the big signs warning about death and the third rail over the third rail?

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Trpdoc t1_j93uqif wrote

Yes I saw it. I just have no idea what it is and apparently nobody else here does either

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Se7en_speed t1_j943vee wrote

So an actual answer. There are two rails that the train rides on, these are a few feet apart and you can see them if you look down at the tracks. These are just metal and would be safe to touch (if there isn't a train coming). On heavy rail subway lines (not the green line) the train gets power from an energized third rail that is slightly to the outside of these two riding rails. It's also slightly elevated off the ground so that it doesn't short circuit to the ground. That is how you can tell which one is the third rail.

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bakgwailo t1_j94huq4 wrote

I mean pretty much everyone responding to you knows what a third rail is and is explaining it to you.

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Trpdoc t1_j94mve4 wrote

The god responses came later

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TheSukis t1_j94q1da wrote

They’re not sending their brightest

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General_Liu1937 t1_j9z9ujt wrote

Fun fact: Blue Line uses catenary power when above ground after passing Airport. It is dual modular because it is said there was problems with the third rail use being so close to the ocean (Revere Beach and Wonderland).

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The24HourPlan t1_j93rtof wrote

Cutting medicare

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andr_wr t1_j93zqk7 wrote

What a Boston answer. 😅

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The24HourPlan t1_j94d1mk wrote

Every category has it's third rail. For instance, the third rail of r/Boston is asking a serious question with the expectation of receiving a serious answer.

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damariscove t1_j94c4ho wrote

Why are we downvoting this comment? Don't we want to encourage curiosity? Especially the life-saving kind?

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Trpdoc t1_j94mrr6 wrote

Thank you that was kind of the point of posting the question.

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hce692 t1_j9655a4 wrote

Because in the time it took them to write that whiney comment they could’ve googled it

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TiredCr0codile t1_j93vnnr wrote

It's on the inner side of track typically (far from the platform). The train has a shoe which pulls power from 3rd rail.

Red line and orange line are powered by 3rd rail. Blue is overhead and 3rd rail. Green is overhead.

About 1 ft tall, very noticeable if you look for it.

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hannahbay t1_j943gbw wrote

If you look at the track, there are the two rails that form the track, that the wheels rest on. And then there is a third rail, separate, that provides power to the trains.

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Gorlitski t1_j95b6vw wrote

you could have typed fewer words in to google and gotten the answer faster

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DickBatman t1_j95dq96 wrote

> Everyone talks about it like it’s so obvious

There's a reason for that

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what_comes_after_q t1_j94bbqb wrote

Trains travel on two rails, this is what you think of as a railroad track. Subways can have a third rail. This is not for steering the train, but for carrying electricity.

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spektyte t1_j94ynwm wrote

So you have the two rails the train travels on, and then a third "rail" which is really just a thick (like, several inches thick) wire carrying about a thousand amps of current. The train has another wire that drags along this third rail as it moves, drawing current and making the motor moves.

Since it takes about 1 amp of current to kill a person, touching the third rail is usually a pretty quick way to get yourself killed.

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Jackpicks51 t1_j95inws wrote

The third is not live constantly only gets you if you touch the third rail and another metal completing the circuit and shocked to death As kids we used walk the third rail for a hits and giggles . . you can walk it just don't touch anything else . 2 feet on the third rail no problem 1 foot on one foot on another rail huge mistake. Did he fall or !!!???. Walking the tracks still safer than train surfing!

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Trpdoc t1_j95jq8w wrote

What the hell is train surfing?!!

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LadyCalamity t1_j992syy wrote

Riding on the roof of the train. Not really possible in tunnels but dumb kids do it on elevated/outside trains. You can find videos on youtube of kids doing it. I know it was popular in NYC in like the 80s/90s or something, died out for a bit, and now seems to be having resurgence. And yes, kids have lost limbs and even died doing this.

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General_Liu1937 t1_j9z99bu wrote

3rd rail is where the train gets its electric feed from. If you see on the tracks, there are 2 rails where the train runs on and a "third rail" that is raised up and parallel that has an electric current running through. The train has a few contact shoes on each car that basically rub against it and gain electric current, allowing it to operate. This is for the red, blue, and orange lines. The green line uses catenary, which has direct contact from overhead wires and uses a pantograph system, rubbing under the wire to gain an electric current.

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KawaiiCoupon t1_j93qy22 wrote

It’s so easy to miss and I’m not even 100% sure it’s the one I think it is lol. It also doesn’t seem to be the literal third rail depending on which way you’re looking at it? Idk. Why isn’t it painted red or with like lightning bolt symbols???

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eladts t1_j93tx68 wrote

Paint is not a good conductor, so it will render the third rail useless.

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KawaiiCoupon t1_j93ubhb wrote

Thank you lol. Well someone more educated than me in this should still find a better solution!

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hopefulcynicist t1_j9395vu wrote

Wires are overhead, no third rail.

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wittgensteins-boat t1_j966nea wrote

For the Green line.

Orange. Red, Blue lines have an electrified 3rd rail.

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hopefulcynicist t1_j96cqn6 wrote

Yep, they were asking about the GL ‘grade level’ ped crossing at Park St.

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