What country would have used this configuration? Looks pretty dangerous to me for anyone close! I can just picture someone trying to step over that rail... ZAP!
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Chicago uses this configuration for the L.
I remember something like this in NYC possibly Pen and Central station. There was a shoe that would drop from the locomotive truck sideframe and pick this up when the train would hit the city limit. This is also how the subways would pick up.
I remember it well being warned about the "3rd rail" as a kid growing up in NYC
@gunrunnerjohn posted:What country would have used this configuration? Looks pretty dangerous to me for anyone close! I can just picture someone trying to step over that rail... ZAP!
Well, it's only 600V DC, so the electric power doesn't "jump out at you" like AC high voltage would.
most I have seen usually have a wooden covers in populated areas , but not as dangerous as one would think they are not live all the time. most electrified areas had power dispatchers that turned section on and off as trains passed thru.
I believe DC voltage is a lot more likley to arc than AC voltage
Rick's correct.
Michigan Central Railroad tunnel, Detroit, Mich. | U.S. Library of Congress (LOC)
The shoe on the locomotive contacts the underside of the 3rd rail, which was up off the ground on stand-offs, and protected on its top by a wooden cover.
Mike
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Chicago CTA trains use it. 600V
What is important to distinguish is over-running vs. under-running third rail.
Under-running third rail is what is in Mike's post above, of the Michigan Central electrification. The third rail is mounted on curved brackets leaving the underside of the rail unobstructed and exposed, and the third rail shoes on locomotives / MU cars are spring loaded to force upward against it. This was the hallmark of the New York Centrals electrification (in New York City/Westchester and Detroit). The top and sides of the third rail are covered by an insulating material.
Over-running third rail is what is shown in Gunrunnerjohn's original post. The shoes on the locomotives / MU cars were spring loaded to push downwards against the top of the rail. This design was used in most third rail applications (Chicago's CTA as noted above, as well as the LIRR, the Pennsy's original Penn Station electrification, and the New York City subway system and SIRT). Most of the third rail is exposed.
The New Haven, which used both Grand Central and Penn Station in NYC, had to have their FL9s capable of using both types of 3rd rail.
What makes Gunrunnerjohn's photo unusual is there is no insulation around the rail at all. On the LIRR and SIRT, covers are suspended above the top of the rail to offer some degree of protection (mostly to prevent things falling on the rail from shorting it out, I doubt the covers could support a persons weight).
~C.Vigs
Scary configuration, interesting that they can still have exposed power like that.
Under running on NYC and related but over running on most rapid transit NY subways and the LIRR. Most do have a board over them.
Remember being on an MU train on the LIRR is a sleet storm and it would build up on the top of the third rail. We got down to one or two cars making contact several times but did get to Penn. Trainman was sent out to signal a couple of times. Must have been a miserable job.
CTA's ground level third rail tracks run in highway medians surrounded by concrete barriers. Street level trackage has fenced off right-of-way.
CTA and its predecessor companies have been using the system for over 100 years.
Rusty
What about SEPTA'S Norristown High Speed Line?
The "Roarin' Elgin", The Great Third Rail*, had open 3rd rail in Chicago and out across the prairies. City running in Aurora, Elgin, Batavia and others used trolly wire.
https://www.google.com/url?sa=...m_ICFQAAAAAdAAAAABAD
* Chicago Aurora & Elgin Railroad
@gunrunnerjohn posted:What country would have used this configuration? Looks pretty dangerous to me for anyone close! I can just picture someone trying to step over that rail... ZAP!
I have one of those insulators (from the Baltimore subway) on my desk holding my internet box:
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@PRRMP54 posted:I have one of those insulators (from the Baltimore subway) on my desk holding my internet box:
That's pretty cool, big suckers! 
Growing up in the Bronx near the New York Central, the only tracks I ever knew were 3rd rail powered railroad tracks. We all knew enough to stay away, even when we were acting "dumb and foolish" as most kids did on occasion.
When I moved to upstate NY, it took a while to get used to the fact that the railroad tracks themselves up here wouldn't kill you, but only what ran on them!!! 
By the way, in the Penn Central days when track maintenance wasn't always the greatest, many sections of those wooden covers would be missing leaving the under-running rail itself exposed. But, again, if you lived in the city, you knew better and it wasn't a problem.
Jim
@Fast Mail posted:I believe DC voltage is a lot more likley to arc than AC voltage
No, that's backwards. AC is more likely to arc than DC is.
Back when Edison and Tesla were arguing over the various merits of DC vs AC, Edison's argument against AC was that it was dangerous and could kill people, whereas DC was much safer. AC won out of course, because it is impossible to transmit DC over long distances without huge voltage losses. That's easy to do with AC.
Rich,
With respect and appreciation for your knowledge I would like to clarify my opinion. Voltage does not kill, current kills. Many will argue AC current is more lethal because of frequency and that it more effects the heart. The heart beats in the 60-100 Hz range } However some will argue DC is more sticky and harder to phsically release for the opposite reason, lack of frequency. There seems to be some dissagreement amongst physicists, electrical engineers, and medical professionals.
There is also the question of voltage and wether AC and DC should be compared with AC at RMS, Peak, or Peak to Peak when compared to DC levels, as regards shock and lethality hazard. All things considered I believe AC 60Hz measured at the same RMS value as DC is more dangerous and more likley to be lethal.
However I was commenting on the fact DC is more likley to produce a dangerous ARC than AC. Many DC switches and contact points need some type of arc supression such as a coil. AC by changing direction or polarity limits its arcing. When comparing open voltage (two conductors) of different values seperated by air at the same distance the DC will arc at approx. one half the value of AC at the same distance in like air. This is often noticeable in stick welding.
There is a lot of info written on this subject and I am not an Electrical engineer, the above is only my opinon formed from work experience and reading. regards, kevin
Fast Mail,
I will have to agree with Rich Melvin, as to the "reach out and grab you" effect of AC vs. DC. I spent most of my whole life working on diesel electric locomotives, for EMD, and have actually tripped the ground relay more than once. Since "early" diesels were DC traction, with 74V DC control systems (before computers), the high voltage system was protected against grounds, with a ground relay system, that would immediately drop all loading power. The wheel slip and transition circuitry was all connected to the high voltage system (max of about 1200V DC) through resistors. More than once I have inadvertently "touched" those HV resistors, while another part of me was contacting the electrical cabinet framework. Yes, I sure as the devil FELT it when I tripped the ground relay, but had it been AV, I would surely have been killed.
@Rich Melvin posted:No, that's backwards. AC is more likely to arc than DC is.
Back when Edison and Tesla were arguing over the various merits of DC vs AC, Edison's argument against AC was that it was dangerous and could kill people, whereas DC was much safer. AC won out of course, because it is impossible to transmit DC over long distances without huge voltage losses. That's easy to do with AC.
Here is the relevant physics:
WHICH IS MORE LIKELY TO ARC
AC at the same peak voltage as DC is less likely to arc, because the voltage is lower, and the shorter pulses make it less likely for streamers to cross from one conductor to the other.
AC at the same RMS voltage as DC is more likely to arc. Because the peak voltage (in the case of 60 cycle AC) is almost 50% higher. Its 170 Volts for a 120 Volt RMS system (This is what Fast Mail was describing)
LETHALITY
Assuming the electrical shock is not sufficient to blow you apart or induce a high current arc through your body, a momentary jolt of AC is more lethal than a momentary jolt of DC, because DC just momentarily stops the heart, which can start beating as soon as the DC is removed. AC cause the heart to fibrillate, which means it does not pump blood, and unless you have a defibrillator handy, you have a problem. So that was the basis for Brown (Edison’s henchman) challenging Westinghouse to a DC vs AC duel. Which is what Rich was referring to. The duel was settled using cats as surrogates.
Lethality has nothing to do with transmisison. For that, see the next part
TRANSMISSION
AC is preferable to DC because you can easily raise and lower the voltage at the input and distribution points using transformers. You can’t do that with DC. This was Tesla’s (correct) argument which is what led Westinghouse to champion AC systems and get rich off supplying them
For very long distances, AC is less economical because: a) It needs six wires to carry all the phases, b) AC current is carried only on the very outside of the wire (the so called skin effect for pulsed currents), whereas DC travels through the entire cross section of the wire. So for thermal management AC wires must be much bigger to carry the same current, and c) per the breakdown argument above, both types of wires must be rated for their peak voltage. Say 120,000 volts DC but 170,000 Volts AC. Because the AC average power is lower, an AC wire can only transmit around 70% of the power as a DC wire. I can not recall off hand what the break point is. But its not that far--200 miles or so.
Now back to the discussion of outside third rails
Hot Water,
I believe if I am reading it correct, you are saying on more than one occasion you came in contact with High DC voltage and that you were saved by ground relays opening? Much like a modern day GFI principle.
My point is DC voltage is more likley to jump (arc) through air than AC voltage measured in RMS at the same voltage as the DC. I believe ( "reach out and grab ya" ) is the arc I am reffering to.
However in the last 30 minutes I have read a study that says as far as being able to "let go" it is easier to let go of DC than AC. The threshold to still being able to physically release and above which voluntary release is not possible. is lower for AC at 60Hz. This study contradicts my earlier statement that I found DC stickier!
Side note, I am a USCG Licensed Chief Engineer, while affecting repairs on a weather deck VDC main feeder, during a mean storm on the Gulf of Alaska. The insulation was compromised when parts of the focsle hatch hit after a relly big wave. The feeder was accidentally re-energized for a couple of seconds. 250VDC. Oh bad scene! blew two holes in my coverall right were my cheeks were sitting on the wet deck. Left me a couple of burnt butt cheeks and slightly scrambled thinking. So you see I have seen that light as well....and it is bright.
K
@gunrunnerjohn posted:What country would have used this configuration? Looks pretty dangerous to me for anyone close! I can just picture someone trying to step over that rail... ZAP!
GRJ - the "what country" made me laugh... have you not looked in your own backyard?!
SEPTA's Norristown High Speed Line (formally owned by Red Arrow Lines, and P&W RR before that) uses semi-exposed 3rd rail like that - see this picture here. While it does have a cover, it is still relatively exposed to the point where there are no grade crossing and ROW access if extremely limited.
The problem with DC transmission is simple, you said it yourself. It's not easily jacked up to the high voltages needed for long distance transmission! So, DC isn't really more economical for long distances because it's simply not practical to use it for power distribution!
@Prr7688 posted:GRJ - the "what country" made me laugh... have you not looked in your own backyard?!
SEPTA's Norristown High Speed Line (formally owned by Red Arrow Lines, and P&W RR before that) uses semi-exposed 3rd rail like that - see this picture here. While it does have a cover, it is still relatively exposed to the point where there are no grade crossing and ROW access if extremely limited.
That's great, I never noticed, and I've actually been on that a few times.
Lets keep the record accurate as it relates to DC transmission. It is widely used throughout the world. Most offshore windpower in Europe is brought back to land on subsea DC cables. Here in the US the largest and best known DC line is the Pacific DC Intertie between The Dalles at the Columbia River and the Sylmar Converter station in LA county. It carries 3.100MW at 500KV DC.
The break even distance for high capacity DC transmission is generally greater than 300 miles. The major advantage beyond lower cost is it allows large power transfers between electrical systems that are not synchronized.
DC does arc pretty good
@AmFlyer posted:Lets keep the record accurate as it relates to DC transmission. It is widely used throughout the world. Most offshore windpower in Europe is brought back to land on subsea DC cables. Here in the US the largest and best known DC line is the Pacific DC Intertie between The Dalles at the Columbia River and the Sylmar Converter station in LA county. It carries 3.100MW at 500KV DC.
If you actually want to keep the record straight, let's do that. As for "widely used", it's a fraction of the power transmission that uses AC.
The reason that DC transmission isn't more widely used is it's considerably more expensive to implement, and it's not as reliable as AC transmission. The conversion equipment is both costly and not as reliable as a big transformer.
Most underwater crossings built in the last 25 years are DC, including in US western states. Most energy moves on AC lines since they are easier to build and are more economical for transmission lines 220kv and above less than 300 miles long and for all distribution lines. Globally there is more than 100GW of HVDC in use with another 270 GW in construction or in the permitting process. Admittedly much of the new construction is in China. Converter stations are now as reliable as needed, unlike a decade ago. Wind power and battery storage are driving rapid developments in converters and DC transmission.
@SLQ32 posted:I remember something like this in NYC possibly Pen and Central station. There was a shoe that would drop from the locomotive truck sideframe and pick this up when the train would hit the city limit. This is also how the subways would pick up.
I remember it well being warned about the "3rd rail" as a kid growing up in NYC
Nyc subways hsve a shield over the 3rd rail plus the third rail in the picture is upside down track rail. Nyc subway 3rd rail is right side up like track rail.
It must be european as the rail itself is BOLTED to the ties, not spiked or Pandrol clipped.
@prrhorseshoecurve posted:Nyc subways hsve a shield over the 3rd rail plus the third rail in the picture is upside down track rail. Nyc subway 3rd rail is right side up like track rail.
I think i know, there was no shielding in the tunnels when i was a kid. We frequently hide and would throw scrap metal and watch the fireworks.
I think the DC (the Capital, not the current) Metro has the type of rail where the top is exposed, but they have a white shield a few inches above it.
As for what’s more dangerous, I don’t know. I do know the voltages involved are enough to overcome the resistance of your skin and allow lethal currents to flow. Whether the current stops your heart or fuses your joints together, matters not. Just avoid at all costs.
DC has steadily risen in popularity for extremely high voltage transmission lines from my research on the subject. It’s mainly used for really long distances and for connecting AC grids that do not sync with one another (say 50Hz and 60Hz AC grids). DC is a higher arc risk though, since AC crosses zero twice per cycle it will often extinguish itself.
@gunrunnerjohn posted:What country would have used this configuration? Looks pretty dangerous to me for anyone close! I can just picture someone trying to step over that rail... ZAP!
An educated guess, based on the high mounting of the third rail and possibly narrow gauge track, it might be the line of the "Yellow Train of the Pyrenees" in France. The line dates from 1909 and uses 850vdc. Or some other vintage line in Europe.
The London Underground and former Southern Railway network of England use exposed third rail electrification extensively, but their third rail is not mounted that high off the ground. The higher mounting might be for snow country.
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@SLQ32 posted:I think i know, there was no shielding in the tunnels when i was a kid. We frequently hide and would throw scrap metal and watch the fireworks.
You must be pretty old because New York City subways have had Third rail protection boards since the verrrry early 1900's
@bluelinec4 posted:You must be pretty old because New York City subways have had Third rail protection boards since the verrrry early 1900's
Don’t know anything about the history of it. But i know what we did as kids in Queens.
There is a lot of interesting expertise in this group, not all in agreement, and it has made for interesting reading, but we still have not determined the location of the photo, except to posit that could be in Europe.
It has that European look to it, that's for sure. I am familiar with many of the examples posted, but not something as exposed and high as that one.
Philadelphia subway and elevate use outside third rail.
The early electric train service from Philly to Atlantic City used overhead wire at each end but used outside third rail across the barren central South Jersey flat lands.
I have photos of NJ grade crossings where the outside third rail is interrupted for auto and pedestrian traffic.
Wandering kiddos or pets could have easily entered eternity. 
@John Sethian posted:...AC at the same RMS voltage as DC is more likely to arc. Because the peak voltage (in the case of 60 cycle AC) is almost 50% higher. Its 170 Volts for a 120 Volt RMS system...
And this is precisely why I stated that AC is more likely to arc than DC.
The typical voltmeter that a layman would use shows the RMS voltage. If you stick that voltmeter on an AC circuit and read a voltage, then measure a DC circuit that shows the same voltage, the AC circuit is more likely to arc.
