Third rail and grade crossings on the Harlem Line

[aegrotatio]

I'm curious how the third rail is handled on grade crossings on Metro North's Harlem Line.  I didn't think of this until I realized there are several grade crossings there and the line uses EMU cars and third rail, not catenary.

 

[Dutchrailnut]

very simple, the third rail stops about 50 foot before crossing and continous about 50 feet after crossing.

 Real trains coast very well, and do not need continous power like model trains.

[blue streak 1]

For a grade crossing 50 ft each side of road and a 30 ft roadway is 130 ft. Even a 2 car EMU is 160 ft long and 140 ft from fartherest third rail shoe. so even if stopped on road still can get power and a 4,6 ,8 10 car EMU train will have many cars powered at any time. EMUs are set up so even if 1st car is not powered it can still control the rest of a train.

[aegrotatio]

I'm curious how many cars can one shoe provide power to?  Do they derate themselves to avoid burning out?

 

[Dutchrailnut]

• On MNCR's Harlem and Hudson line the cars are in pairs, on one pair there is 8 shoes, it only takes one shoe to touch rail to power those two cars.

 On New Haven line there are some triplets (M-4 and M-6) thuese  there are 12 shoes on 3 cars, it only takes one shoe to touch third rail to power 3 cars.

  third rail power does not trainline through electric couplers. the electric heads only handle control circuits..

 and no there is no power reduction for shoe situations, each shoe is good for around 1000 amps at 770 volt

[CSSHEGEWISCH]

Grade crossing gaps have never been a problem on the CTA and I've ridden through them frequently in the past on the Douglas Park Line.  The only gap that could have presented a problem was at Forest Park where the Garfield Park line crossed the B&OCT at a sharp angle.  This crossing was eliminated with the construction of the Congress (Eisenhower) expressway in the 1950's and the replacement of the Garfield Park Line with the Congress Line.

[tomikawaTT]

There are third rail gaps of similar length at specialwork, even in the underground portions of the New York system.  First time riders are sometimes startled when the lights in the car go out for a second or two as it crosses the gap.

Of course, the former NYC used third rail locomotives in the real puzzle palace throat of Grand Central, where the gap through specialwork could be several hundred feet long.  The solution was third rail suspended from the tunnel roof, contacted by heavily-constructed miniature pantographs.

Chuck