• What is a diamond in train lingo?

  • General discussion about railroad operations, related facilities, maps, and other resources.
General discussion about railroad operations, related facilities, maps, and other resources.

Moderator: Robert Paniagua

  by Sir Ray
I guess you're asking about the crossing (intersection) of two rail lines, the middle rails at the intersection forming a 'diamond' shape.


If not, we need more info on what you do want to know...

  by JacobBruce

  by AmtrakFan
Thanks for sharing Mr. Vondrak.

  by ACLfan
"Diamonds" are also referred to as "interlockings".

  by eddiebear
Go out to Palmer, MA. There's a new diamond on the ground and the one in place is scheduled for replacement within next few weeks.

  by ACLfan
Yep, these days and times, any "diamond" worth its name is an "interlocking".

Crossovers and things like that aren't diamonds.

We're talking about diamonds and interlockings.


  by ACLfan
Yup, OK.

I'm not familiar with places like East Podunk and similar scenic places that don't have interlocked diamonds.

Didn't know that such places existed!

How many trains a day? 1/2 ? [Just kidding!]


  by thebigc
David Telesha wrote: There are non-interlocked crossings - so therefore not all are "interlockings". It depends on the territory - Brighton Park is an example of a non-interlocked and a mandatory stop is required.
Are you referring to Brighton Park on the CJ in Chicago? It's interlocked, or protected by home signals, but a stop is mandatory regardless of signal indication. I believe Center St. in Youngstown, OH was set up much the same in it's old configuration with movements controlled by the towerman using a colored lamp for each RR involved there. Don't remember the colors.

  by Aji-tater
Since the question was first asked by someone fairly new, let's try to spell it out in terms most folks will understand.

A Diamond is a piece of trackwork whereby one track crosses another. Think back to the old Lionel sets, many had a 90 degree "X" so the train could go in something of a figure 8. In real life there are 90 degree diamonds, and there are also diamonds at various angles OTHER than 90 degrees. Sometimes diamonds are used in tight industrial trackage, and in those cases there is usually no protection for trains moving in different directions - the idea being that the area would probably be used by one crew, at low speed, and they are not likely to collide with themselves. When a diamond is on a track with heavier usage such as two branches of a railroad or a crossing between main lines of 2 different railroads, there needs to be a system to keep trains from running into each other.

Rulebook definitions of an interlocking may vary slightly in wording but are all essentially the same idea: "An arrangement of signals and signal appliances interconnected so their movements must succeed each other in a pre-arranged sequence and for which interlocking rules are in effect. It may be operated manually, remotely, or automatically".

So at a diamond where protection against conflicting movement is desired, some sort of system is set up, with rules governing their use. It may be a train stops at a certain place, a crewman pushes a button, and when his signal goes green the train may proceed. Obviously it would be arranged so when his signal is green, the OTHER track would have a red signal.

Or the whole thing may be controlled by a dispatching system hundreds of miles away, with the interlocking part of a larger signal system allowing trains to proceed across the diamond non-stop.

And an interlocking does not necessarily involve a diamond; as a couple folks have mentioned above it may be a location where a branch diverges from a main line and may involve one or more switches but not a diamond.

I hope this helps answer your question.

  by ACLfan
ZZZZZZZZZZZZZZZZZZZ...... Wow! This is a lot of type just to answer a simple question.

Let's not try to make it confusing with a lot of wordy definitions and rules.

What it boils down to is a "diamond" is the physical hardware for two sets of tracks to cross each other at an angle.

For goodness sake, leave other situations such as "crossovers" out of the discussion, as "diamonds" and "crossovers" are two different topics!

Because of the significant concern for safety, virtually every diamond is protected by some form of "interlocking" measure.

It is extremely bad for two trains to meet at the diamond at the same time. Really tragic things usually happen.

"Interlocking" applies to the protection of all four directions toward the diamond. Perhaps a better word would be "Interprotection".

Interlocking devices range from manually-operated stop boards to remotely-controlled CTC signal lights, with a lot of other examples in between these two examples. Because of this design, these crossings are generally referred to as interlockings. I can't remember the last time that I heard someone call those things "diamonds".

But, if calling them "diamonds" helps you row your oars, then have at it! It don't scratch me none!

I've been working for over 30 years, and in all of those years, I've seen a lot of "diamonds", but I've only seen one (1) diamond without some form of interlocking protection. It was on a private industrial property that both the ACL and SAL served back in the 60's. The two sets of tracks crossed each other on the property to serve the various loading docks. We treated the operation as two customers from a work standpoint (since we had to use two sets of rails to access each portion of the property), but one customer in terms of billings.

Since there was only one switch job assigned to that customer, there was very little chance that two trains would try to use the diamond at the same time.

So, if you see a "diamond without some form of interlocking protection, take a picture of it! ---cause you won't see many of them!

As always!


  by BlackDog
I can think of 2 diamonds right now that are used by 2 different railroads that are not protected by an interlocking. One is Newtons crossing in East Superior where the UP (former Omaha) crosses the BNSF (former NP). No stop signs, just special instructions to stop and procede. At one time there used to be a tower there, but now both lines are in yard limits and their status of mainline and high traffic density has diminished quite a bit in the past few years.

The other is in David City NE, where the Nebraska Central (former UP) crosses the BNSF (former CB&Q). Not yard limits, both roads have a stop sign and must stop and ascertain that the way is clear before they can procede. There is a book written about the UP branch, called "The Stromsburg Branch" and it shows a pic of the UP and the BN after neither one stopped for the sign, wasn't pretty.

  by steemtrayn
ACLfan wrote:
So, if you see a "diamond without some form of interlocking protection, take a picture of it! ---cause you won't see many of them!

As always!

A diamond without an interlocking:

http://community.webshots.com/photo/465 ... 3842EYHYMN