DCC Polarity question

[ndbprr]

I am building the corridor through a section of Philadelphia. This is basically 6 tracks wide with three in each direction. The outside track on each side is used for switching the industries and the four inside tracks are the mainline. However, on either side of North Philadelphia station is the ability to cross over from track 1 to track 6 and at the other end from track 6 to track 1. This is critical for the switch crews to get to track one from Margie Yard on track 6 west of the station. Since the layout is to be a big dogbone with loops at the ends it makes sense to wire it accordingly as a loop. Here is the dilema and the question. If I install one of those automatic current reverser modules so when one of the switch crews crosses all the way over what happens when it gets to the normally wired sections at either end? Would I be better off to have a spring loaded double pole toggle for the crews to use while they cross over and then return to the normal wiring? Thank you.

[cacole]

You're going to need two auto-reversers -- one where the trains cross from track 6 to track 1, and one on the reverse loop.

Read about the PSRev from Tony's Train Exchange at http://www.tonystrains.com/technews/new_pscombo_details.htm

[ndbprr]

But if I isolate the turnouts across the three tracks eastbound and enough of track 1 so I can run the while train across and then stop it, release the double pole switch and the restart the train wouldn't that be the same thing a lot cheaper?

[ClinchValleySD40]

QUOTE: Originally posted by ndbprr

But if I isolate the turnouts across the three tracks eastbound and enough of track 1 so I can run the while train across and then stop it, release the double pole switch and the restart the train wouldn't that be the same thing a lot cheaper?

Cheaper yes, but you're missing one of the great advantages of DCC - auto reverse. I've got four of them and crews don't slow down or think about it, just keep running. Like the ads say "operate your train, not your railroad".

[ndbprr]

There is no reverse loop becasue the three eastbound tracks basically make a 180 degree loop and come out as the three westbound so there are just three loops of track totaling the six tracks. I was planning to have the bus lines loop with the tracks so I don't see the purpose of the second auto-reverser.

[cacole]

If the polarity on all six tracks is identical, you don't need an auto reverser at the crossover. I thought one of the tracks was coming back from the reversing loop. Sorry about the confusing answer.

[ClinchValleySD40]

QUOTE: Originally posted by ndbprr

There is no reverse loop becasue the three eastbound tracks basically make a 180 degree loop and come out as the three westbound so there are just three loops of track totaling the six tracks. I was planning to have the bus lines loop with the tracks so I don't see the purpose of the second auto-reverser.

Three eastbound tracks turn back and become three westbound tracks? If so, if you have any crossovers between the eastbound and westbound tracks you will have a short circuit situation. Am I understanding the track layout correct? Simple solution if this is the way you have it set up.

[nfmisso]

QUOTE: Originally posted by ndbprr

Since the layout is to be a big dogbone with loops at the ends it makes sense to wire it accordingly as a loop.

No !

The easiest wiring scheme is to have all six tracks in the same polarity, and isolate the turnaround sections at each end using autoreversers.