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 NUMBER NINETY TWO

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© SEPTEMBER 16, 2007  

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The Automation of Adobe City

 

 


 


Written by Jim Brown

At Maricopa Live Steamers in Phoenix Arizona we have fully automated the signal system and routing of trains in and out of the Adobe City area by the use of a PC based computer. In recent times Bill Lowe has written an article on how we build switches. Al Ford has written on the automation of those switches. This is next installment from Maricopa Live Steamers signal department.
If you look at the track plan (left), you will see how all five of the branch lines and Schnyder Yard come into and out of Adobe City (click image to enlarge). With all this action that goes through the interchange in front of Adobe Tower, we need a system to control all of the trains.

The initial integration of the system was researched and installed by Robbie Diehl. As time went on the system was expanded and improved and a fully automated system was developed.

We have developed three different computer programs for our signal system in Adobe City. They are 1: Dispatcher on duty, 2: Operations (when we are running an operation session on the railroad), and 3: Automatic.

Let me explain a little about each program. For dispatcher on duty, which we use when there is high traffic (for example during our meets), the dispatcher has control of all trains entering and leaving Adobe City. By pushing one key on the computer keyboard for a train arriving or two keys for the trains leaving the dispatcher can align routes and turn signals to the appropriate indication. The computer performs a "check" for opposing traffic and will not allow the dispatcher to route two trains into each other. In the Operation modes, a lot of the "fail safes" have been removed which gives the dispatcher even more control over traffic. In this mode it allows for moves that are needed during operations, but not during a simple run. The last and coolest is the automatic program. With this there is no dispatcher required to be on duty. The computer, through track detection, knows when trains are arriving and can automatically align the inbound route turning signals and switches to the appropriate indication and alignment. The computer sees what traffic is present and selects which train gets to proceed. When a train wishes to leave Adobe City the engineer pushes one of five buttons, relative to which branch they want, next to his departure track. This notifies the computer where a train is and on which branch they wish to go to. When the route is clear the computer aligns all switches and changes the departing train’s signal to green.


click image to enlarge

This photo (above right) shows the electronics that are used inside of the Adobe Tower . The large rectangular boards are IO 48 boards produced by Oak Tree Systems (may not be available) We use a total of 7 of these boards to control 34 individual signals, operate 23 switches machines, show track detection in 23 separate blocks, receive information from 45 push buttons, show switch alignment from all 23 switches and align numerous routes. This may sound very complicated but the basic system is quite simple.
The second key to our system after the circuit board is the computer software. Here is the track diagram that appears on the computer screen (left) which is used by the dispatcher inside of Adobe tower (click image to enlarge). The software that we use is Railroad and Company Train Controller, found at www.freiwald.com. The beauty of the software is it that it is a point a click program. You design your track diagram by clicking on the track section needed and place on the diagram. Programming each item is as simple as choosing the item, i.e. a two color signal, placing it on the diagram where you need it and then setting the properties. I will get into this shortly.
To control the switch machines that Al Ford talked about in the previous article, we run 18 gauge 7 conductor direct burial sprinkler wire. We use two of these conductors for the plug which plugs into the switch motor. We use three conductors to connect the switch alignment circuit and the other two for spares. If you look (right photo) you will see two magnetic switch relays that are mounted to the turnout (click image to enlarge). The magnet is mounted on the throw rod. This is the type of relay used in the home security industry on doors. They are extremely reliable and cheap. When the turn out is thrown the magnet moves activating the relay to show which way the points are aligned for. If the correct indication does not light on the computer screen we know that the points are not all the way over.
As Al Ford talked about in his article we use a very short pulse of DC power to activate the switch machine. The length of time that the power is on is set in the property menu on the computer. We simply use two relays (left) in the tower to switch the polarity of the power to the motor (click image to enlarge).
For each of the signals we again use 18 gauge sprinkler wire. We use super bright LEDs for the lights, so it takes very little power compared to bulbs. There is also the added benefit that they are longer lasting. We simply put a resistor in line with the circuit on a small board made for this purpose from Oak Tree (right) then use the software to control the signal (click image to enlarge).
So far we’ve discussed the outputs. The inputs of our system are the track detection and the push buttons. Both of these, obviously, are run to the input side of the Oak Tree boards. For track detection we run 14-2 with ground direct burial wire. One wire is connected to each side of the track. When the wires come into the tower they go into a board designed by our electronics guru Bill Pardee (right).  This board simply has a small reed relay and drop down resistors. The resistors are used so we can "fine tune" each block so it is not affected by water (it does rain once a year here in Phoenix), or due to the length of distance from the tower to each block. The relay simply sends a signal to the Oak Tree board by closing the contacts telling it whether it is activated (train in block) or not.


click image to enlarge

The pushbuttons we use (left) help make our system engineer friendly. Which pushbuttons are active is dependant upon whether we are running in a dispatch mode or automatic mode. The pushbuttons once again are connected with 18 gauge sprinkler wire. The pushbuttons allow the engineer to select which route they would like when departing Adobe City or, upon return, to select the freight or passenger route around Adobe City and then one of four passenger tracks in the station or the main yard.
The software is very user friendly. Once you have designed your track diagram and placed all of your items on the track, for example signals, switches and track detection the programming can start. You simply select any item and open the properties for that item. In the properties menu you select items that can be affected by the item being programmed by either choosing items on the right side of the properties screen or by using the record function where you simply click on the affected items. Let’s use the signal at the yard entrance (Engine Lead, just past switch 14) (see computer screen image above) on the diagram as an example (see computer screen image right). Selecting record mode, click on any other signal that would allow trains on the same track. By clicking on them the computer is programmed so that this light can only be changed to green if the other lights are red. You continue programming this with track detection. Now the computer will not allow a train to proceed from the yard unless the lights and track detection are showing the correct color and no occupancy. Continue programming your other signals in the same fashion.


click image to enlarge

The other main function of the software is the aligning of routes. To program a route, pull up the property on the route icon and click the beginning of the route and the end of the route and the computer will program the correct switch alignments and signal indications for the route. Once this is completed to operate the program if a train is inbound simply select the in bound route by clicking on the route icon or the "hot key" which was assigned and the computer does the rest.  For a train leaving the dispatcher simply selects a departing route and the track the train is on and the computer does the rest.
This is a very good and reliable system. Because of this the training of new dispatchers has been found to be very easy requiring only a short amount of time. New dispatchers are generally not shown how to access the edit mode to make changes simply to limit the number of people who make changes, but the system is easy enough to use that they could be should it be required.
I would like to thank other members of the club, Al Ford, Jim Manley, Bill Pardee, Pete Pennarts and numerous others which have done so much in helping to build our system such as digging trenches, placing wire in the ground or providing feedback on how the system has been operating.

 

Written by Jim Brown

 

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