Double crossover question: Why wouldn't you always throw all four switches?

We have a little semantic problem here.  The two crossovers in series were traditionally known as "double crossovers".

The crossover arrangement Mr. Burfle shows were traditionally known as a "scissors" crossover.  With a scissors crossover you might as well throw all four at one time, if it turns you on . . .

EdKing

Wikipedia bears out Ed's description. They even show a picture of a "scissors" crossover.

http://en.wikipedia.org/wiki/R...oad_switch#Crossover

Another site shows several examples of crossovers that appear to be in Europe and they are all called double crossovers. There are also many model examples that are all double crossovers.

http://www.google.com/search?q...biw=1280&bih=866

The model world appears to be influenced by Europe and or the Pacific Rim as far as nomenclature.

Yes Wikipedia does agree with Edward King.

On the other hand, several model railroad suppliers, including Kato and Walthers refer to the "scissors crossovers" as "Double crossovers".

"The Boy's Book of Model Railroading", by Rayomd F. Yates also refers to the "scissors" configuration as being a "Double Crossover" in a captioned drawing on page 40.

Hence the confusion.

I am just glad to have provided the picture.

We should also remember that Wikipedia and many other internet resources are not authoritative or particularly accurate (not that I'd place a bet based on the sources I named).  Look at this definition of a scissors crossover:

I believe that the most common definition of the switch pattern we are talking about, that is: two parallel tracks, four switches (aren't they actually called turnouts?) connected by a crossing.  If you separate the switches into pairs allowing for a crossover movement from only one track to the other, you have what we call a single crossover.

I have never heard, prior to reading the Wickedpedia description, of a "scissors" crossover.  I suspect that the terms is more European than American.

In either case, there are only two choices for switch alignment for this track arrangement as Rich points out; either both tracks straight or both tracks diverging. Ya can't have one track going straight and the other diverging.  You would have the type of an accident that makes news headlines as a "derailment" with trains lying all over the countryside!  So, to make control of the switch as simple as possible for the operator, the best way to control the whole "plant" is with one control switch with only those two options: straight or diverging.  How you do that mechanically is your own choice.

Interesting and informative discussion here. 

Another interesting track arrangement and somewhat similar to a double crossover is the double slip switch.  Now, on this device, you can only have one train passing through at a time, for obvious reasons.  But, just like the double crossover, you really can have only two possibilities: straight through the crossing or diverging in either direction.  However, many of the track manufacturers have their double slip switches set up requiring two switch motors.  This, of course, does then require two control switches.  It would be a great feature on a double slip switch to have all points move in such a way that they are either set for straight or curved.  Again, it would make control of the plant much easier.

Paul Fischer

Despite all the semantics, you still need to power the switch(es) so you can get a train across.  We are dealing with electricity here and three rails supplying it. 

The original question was about a Ross dbl crossover. There should be no confusion as to what that is.

Doug

In dealing with the prototype for all those years, I never heard a "scissors crossover" referred to as a double crossover.  The double crossovers I referred to in an earlier post were all four turnouts separated.

We modelers like to flaunt our fancy trackwork in areas where the prototype never would.  If there was room to do it, a real railroad would spread out a scissors crossover to get away from the troublesome diamond in the middle. 

Similarly, a real railroad wouldn't use a slip switch if there was room to put two regular turnouts facing each other.  But we like to show 'em off, so we do.

EdKing

Well said.  I wanted to limit the switches on my 2 mainlines and my thought process was to consolidate them in one spot.  In retrospect I was trying to get too fancy.  I would have been better served operationally and practicality wise to seperate them.  I do have it running like a Swiss watch right now, and I have had compliments that it looks cool, but I would do it different next time.  I laid track 10 years ago.  I wish I could say I'm wiser now, but I'd be lying.