Dual Blog: *RMAN (Retain My Asset Names) Asset Renaming Utility* & * Fostoria Ohio, "The Iron Triangle" Project*

Avoiding a Norfolk Southern - CSX Collision

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Both ASB and ATLS are needed to control rail and road traffic at the South Main Street grade crossing
near one of the Norfolk Southern-CSX diamonds in Fostoria

Using the Fostoria terrain only map and Google maps, the true alignment and location of the western Fostoria diamond takes shape. In the above screenshot, the Norfolk Southern's Fostoria District between Bellevue, Ohio, and Fort Wayne, Indiana is shown with the blue hoops ("ASB correctors"). This was originally constructed by the Nickel Plate Road. The yellow hoops are on the CSX's double-track Willard Subdivision, part of the B&O's main line, which runs east-west through Fostoria, and is the railroad's main artery for traffic moving between Chicago and the Northeast.

The ASB (Active Signal Block) system is designed to prevent virtual collisions between trains on crossing mainlines. Fostoria, however presents a configuration beyond the design of ASB, in that there are three main line crossings in town which form a triangle.

If one were to apply three independent ASB set ups to each of the three crossings in the triangle, the risk of grid lock would be instigated. If three trains were to enter each leg of the triangle, they could obstruct each other from exiting the triangle.

In reality, the CSX "F" Tower, located at the B&O-C&O diamond, controls the traffic through town by radio. Engineers radio the tower in approach to Fostoria, and correspond similar to what is done with air traffic control. The objective in this Trainz version, is that portals will feed the Fostoria triangle from each direction with predesignated consists, and an automatic control system will prevent collisions in the triangle, thereby giving the "feel" of radio control tower management.

Fostorians are very patient people!

In practice, Fostoria trains often stop on the diamonds and grade crossings, and speeds can get rather slow, especially since two diamonds also serve to feed yards! It is not uncommon that a grade crossing on a fairly important street be obstructed with a train dead stopped, waiting for mainline or yard track clearance. Also trains "turning" between the C&O and B&O lines, which are about 30% to 40% of the CSX trains, are only moving at 15 to 20 mph, also delaying those gates from going up quickly.

Cam and Radio Observations of the actual triangle...

show that two trains are permitted in the triangle at once, but a third would be forbidden. To have that happen with an automatic control system, it would be necessary to have a "comparative" operator which processes signals from two different trigger channels. The outer triggers on the triangle would detect the approach of a train into the triangle, while an inner trigger set would confirm the presence of a second train in the triangle. If both inner and outer channels are tripped, the red signals would light up which prevent a third train from entering the triangle.

Unfortunately, there is no device in ASB which can compare and react to two incoming channels. Therefore, a simplification will need to be made to use the ASB system in Fostoria. The most apparent alternative is to combine the two closer intersections with the same ASB set up (that is two double mainline diamonds be treated as if four tracks crossed by two tracks). Any comments or thoughts on this problem are welcome.

Updated November 10th, 2018 at 10:18 AM by deneban



  1. boyerm25's Avatar
    GAH! --- Just use the trigger multiple signals thingy - way easier
  2. deneban's Avatar
    Quote Originally Posted by boyerm25
    GAH! --- Just use the trigger multiple signals thingy - way easier
    Hey boyerm25, thanks for the suggestion, I have looked into it.

    I am afraid I am not seeing how using that rule would not cause the same problems. If I added three such "trigger multiple signals" rules to the session to control the three intersections, there is still a potential to develop gridlock (i.e. three trains entering the triangle can obstruct each other from leaving the triangle.)

    Both systems can stop all traffic if one train enters the triangle, but that is not how the real thing operates, because the triangle is too large and too busy for one train at a time.

    As with ASB, without a way to compare two inputs, neither control system can simulate the real mode of operation of 2 trains permitted in the triangle at once, and a third prohibited. A viable control system would stop all traffic from entering the triangle if condition "A": a train is in the triangle, exists and condition "B": a second train has entered the triangle
    , are both happening. That requires a comparison device. Neither the ASB controller nor Magg's rule controller can accept an input from another controller in addition to trigger input, which is what is needed for this objective.

    Also, I don't agree that rule is easier to use then ASB, with Magg's rule, you have to name all the triggers. In ASB you just assign your triggers to the same channel.

  3. boyerm25's Avatar
    Ah, well, I've never understood ATLS or ASB.
  4. deneban's Avatar
    ASB also offers "on triggering" and "off triggering" for a single track. With Maggs' rule, all signals in the rule must clear to trigger the off (all green). This means that if you use Magg's rule on double track diamonds, one of a pair of parallel trains would have to stop for no reason because its counterpart tripped all red.
  5. boyerm25's Avatar
    Actually, say you have a double track crossing. With TMS, you could add two copies of the rule, and have trains on Main1 only trip the signals on Main2, and vice versa. I see how it wouldn't work for fostoria though. If you download Sniper297's chicago metro 3 and the corresponding session (I forget what it is called, something about 40th 2030), you can see how he used TMS to control western ave. (4 track by 4 track) so parallel trains can pass at the same time but no collisions will happen,
  6. deneban's Avatar
    Yes I see your point, I stand corrected. Every approach to the diamond would need its own rule to accomplish that (yikes!).
  7. boyerm25's Avatar
    Yeah, but I see how it wouldn't work for fostoria. It wouldn't allow more than one train to enter at the same time.
  8. deneban's Avatar
    I think I am going with making the two closest 2 x 2 intersections a 4 x 2 intersection, until something else better pops up. This in fact accomplishes the goal of allowing 2 in the triangle.