Heavy Rail Transit grade crossings

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Heavy Rail Transit grade crossings

Postby MattW » Mon Aug 15, 2016 4:40 pm

I've heard that the FTA basically prohibits grade crossings for new heavy rail extensions, but most heavy rail extensions use third rail. Third rail isn't necessarily the issue as shown by the LIRR, MNRR and CTA (though two of the three are railroads, and the third's crossings are legacy), but would the FTA allow grade crossings if new HRT used overhead catenary instead of third rail? I'm guessing not due to the lighter construction standards, but they do allow lighter LRT vehicles to have grade crossings and at-grade segments.

Thanks!

Moderator's Note: edited thread title, 08/20/16
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Re: Heavy Rail grade crossings - catenary?

Postby DutchRailnut » Mon Aug 15, 2016 4:58 pm

why not, for example some of NJT lines have crossings and Catenary, so does MN New Canaan Branch.
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Re: Heavy Rail grade crossings - catenary?

Postby mtuandrew » Mon Aug 15, 2016 5:22 pm

I'd feel far more comfortable designing a railroad crossing with overhead wire than third rail. Overhead wire in some parts of America (Philadelphia CSX ex-Reading, off the top of my head; maybe NS around Jersey City?) is 20' off the ground, and you'd have to really try to hit that with a truck! You wouldn't have to try nearly as hard to weld your car to a 750 vdc third rail at fender level, even if it's 200 feet down the track.
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Re: Heavy Rail grade crossings - catenary?

Postby Backshophoss » Tue Aug 16, 2016 12:13 am

Parts of the NEC still has grade crossings,in the former New Haven shoreline area.
Amtrak closed off all the grade crossings between Philla. and DC.
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Re: Heavy Rail grade crossings - catenary?

Postby Jeff Smith » Tue Aug 16, 2016 10:35 am

Catenary is superior for power transmission, so why not? DC requires a lot of sub-stations, and the MNRR Valhalla grade crossing accident revealed a risk likely not previously known. Unless you're limited by clearance (e.g. Park Avenue Tunnel to GCT) or legacy issues (New York Central or LIRR) why use DC anyway?
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Re: Heavy Rail grade crossings - catenary?

Postby DutchRailnut » Tue Aug 16, 2016 10:50 am

Ok now your confusing things, DC does not just mean third rail, plenty of overhead power systems are powered by DC.
for example Metra in Chicago, and Dutch national railroads at 1500 volt DC and Italy, Belgium at 3000 volt DC.
And with AC propulsion the feed to inverters is DC, so in essence what AC catenary saves you in transmission cost, penalizes the weight on traction equipment for transformers and rectifiers.
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Re: Heavy Rail grade crossings - catenary?

Postby electricron » Tue Aug 16, 2016 11:20 am

Yes, overhead catenary can be both ac or dc, but most, if not all, third rail systems used dc. I'm not aware of any third rail systems using ac, but there may be one I'm not aware of.

And I'll repeat this rule of thumb again just for FYI reasons, it takes 1kV per mile to push ac selectricity from a source.
So, on a 25kV catenary, gaps in the catenary can be up to 50 miles apart with the feed in the middle. On a 12kV catenary, the gaps can be up to 24 miles apart with the feed in the middle.

Also, on ac systems you see gaps because one can't guarantee synchronization of the different voltage supplies, while on do systems gaps aren't needed as long as the supply polarities are correct.

There are advantages and disadvantages for both ac and dc systems, but in general ac systems become better the longer the railroad corridor is.
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Re: Heavy Rail grade crossings - catenary?

Postby MattW » Tue Aug 16, 2016 4:02 pm

Perhaps I should have phrased my question better. The question really doesn't have much to do with the electrification. Really I'd just like to know if Heavy Rail is allowed to have grade crossings at all. I only mentioned the electrification because at one time I had heard that it wasn't allowed, but I don't know if that's because most HRT is third rail, or because HRT just can't have grade crossings regardless of power supply.
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Re: Heavy Rail grade crossings - catenary?

Postby DutchRailnut » Tue Aug 16, 2016 5:06 pm

only restrictions on Heavy rail and rail crossings is they are not allowed in territory where track speed exceeds 110 mph.
as for Catenary it can be installed high at crossings with physial truck clearance of nearly 25 feet high, 14'6" for basic single level and a pantograph reach of 10 to 12 feet.
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Re: Heavy Rail grade crossings - catenary?

Postby mtuandrew » Tue Aug 16, 2016 6:16 pm

MattW wrote:Perhaps I should have phrased my question better. The question really doesn't have much to do with the electrification. Really I'd just like to know if Heavy Rail is allowed to have grade crossings at all. I only mentioned the electrification because at one time I had heard that it wasn't allowed, but I don't know if that's because most HRT is third rail, or because HRT just can't have grade crossings regardless of power supply.

MattW, are you talking subway-style opposite-of-Light Rail Transit, like the Chicago L or the Washington, DC Metro, or are you talking FRA-compatible common carrier railroads like Amtrak's NEC?
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Re: Heavy Rail grade crossings - catenary?

Postby MattW » Tue Aug 16, 2016 8:01 pm

mtuandrew, yes, I am, more specifically Atlanta's MARTA. But, if the proposed extensions used catenary. So basically the MBTA Blue Line north of Airport, or Cleveland's Red Line. It's still heavy rail, but it's using catenary; would public, revenue-trackage grade crossings be allowed? What triggered this general question, is the new MARTA car order. MARTA's own RFI indicates the possibility of pantograph capability and some of us are debating if that means they're looking at allowing grade crossings on any of the planned extensions.
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Re: Heavy Rail grade crossings - catenary?

Postby mtuandrew » Wed Aug 17, 2016 6:29 pm

Interesting question, MattW.

I'm inclined to say that MARTA could include grade (level) crossings, but that would pretty much throw their Automatic Train Operation out the window. Chicago has a number of grade crossings on its outlying branches, all with third rail, but they may be the only such American system with grade crossings. New York's last crossing was eliminated ca 1973, and I can't see any others on heritage (Boston, Philadelphia), "bicentennial" (SF BART, DC WMATA), or new-build (LA, San Juan PR, Miami) systems.
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Re: Heavy Rail grade crossings - catenary?

Postby bdawe » Wed Aug 17, 2016 8:25 pm

mtuandrew wrote:Interesting question, MattW.

I'm inclined to say that MARTA could include grade (level) crossings, but that would pretty much throw their Automatic Train Operation out the window.


I believe Muni Metro is ATO inside the Market Street Subway, despite being light rail/streetcar operation outside of it, so presumably you don't have to abandon ATO to have manual operation segments
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Re: Heavy Rail grade crossings - catenary?

Postby ExCon90 » Thu Aug 18, 2016 2:26 pm

True--a train coming from Caltrain or the "T" must stop on the ramp leading to the tunnel portal, then "advance and be recognized" before getting a signal to proceed into ATO territory. For some reason this often takes a few minutes, but this is presumably a glitch that could be straightened out. For some reason it doesn't seem to be a problem for trains in the opposite direction at West Portal and Church & Duboce. I think I've read somewhere, however, that the FTA may simply be opposed to new grade crossings in principle, as MattW mentioned upthread, and with good reason considering the behavior of many motorists at grade crossings.
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Re: Heavy Rail grade crossings - catenary?

Postby bdawe » Thu Aug 18, 2016 9:04 pm

I was also under the impression that the FTA wasn't a regulatory agency, rather a funding agency like the FHA, and while they might whithhold support form operations they do not approve of, they don't regulate directly like the FRA
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