Dogbone Traction, Part 2
By Sanford Mace
The original "Dogbone Traction" article, now designated as Part 1, is at our sister site, V-Scaler.com.
A little while ago Al Barten produced a dogbone traction route and wrote about it in V-Scaler in an article entitled, appropriately enough, "Dogbone Traction." I read the article and liked the little route a lot. I wanted one. I am sure I could have asked for and received a copy of the route, but this is a Trainz route and I do not own a copy of Trainz. I do have MSTS and BVE though, so I decided to make versions for those simulators.
I know how to make routes for BVE, but at the beginning of this process I did not know how to do routes for MSTS. So we start with BVE.
Lets review what Al created. Look at his original article and the screen shots. He is using HO scale, or 1:87. The length of his route is about 8.5 feet by 1.3 foot with 9” (.75 foot) radius curves. Or 740’ (225.5 m) by 113 (34.5 m) with 65 foot (20 m) radius curves. This will give a total route length of about 2200 feet (670 m). Note there is a lot of round-off error here; we are just trying to get an idea of what we want to build. This is a dogbone-shaped loop running North-South (not specified in the original article, but will make sense later). There are 2 sidings running south off the East track, a station siding and a freight house/maintenance shed. The overhead support is old North American roadside trolley/interurban wood support poles. This gives us our general parameters. We are not going to produce an exact model of the model. We are going to produce the same type of layout that is close to the look and feel of the original.
Loops in BVE
Creating loop routes in BVE is easy. There are several routes that are loops. The Glasgow Subway (aka, Clockwork Orange), The London Underground Circle Line - Inner rail (Aldgate-Aldgate) are two that come to mind. There are others. Included in the reference material for this article, available at the Virtual Railroader Downloads) page is a route called Great Circle. Please pause now and run that route. (If you do not have the correct train, change it to one you have.)
Figure 1. Great Circle route.
Figure 2. Great Circle route from above.
Ok you are back. That looked like a 4-lap loop. Now the BVE loop secret: BVE does not do loops. BVE works by moving a digital world past a standing train in a 600 meter long by about 600 meter wide segment. Loops are created by repeating the same segment of track over and over. Pause here and run the Straight Circle route included in the reference material.
Figure 3. Straight Circle route from same view as figure 2.
Figure 4. Straight Circle route from above.
This is the same as the Great Circle route without curves. The Great Circle route looks like a loop because, as I told you, it was a loop and because it resembles a loop. Modeling 101: make the viewer see what is not there. This means all we have to do is make one copy of the loop track code and then just repeat it over and over. Look at the text of the Great Circle route. There are 15 lines of code from Begin Loop to End Loop that just repeat. You can make a VERY long route with a very small set of commands. This gives us an advantage. Because each lap of the loop is an explicit set of commands, we could change what is placed alongside the track for each lap. We could change the cars stopped at the crossing or station or the number and kind of people at the car stop. We are not going to do this for the basic loop, but we could.
There is only one more thing to consider. Pause here and run the Loop Back route in the reference material. Here you see that if a curve in front of the train is tight enough, the moving front of the world at 600 meters will move past the train in the opposite direction. You sometimes see this in a route that is long and flat. The front edge of the world appears in the distance. Further, once we are around the curve the track behind us is gone.
Figure 5. Loop Back route start.
Figure 6. Loop Back route with world front appearing in distance.
Figure 7. Loop Back route with world front from above.
Figure 8. Another angle showing the world front about to pass us.
Figure 9. Around the corner the track behind us is going away.
Now if we make the loop short enough so that the 600-meter world front is BEHIND the train, we do not see the world built.
With all of this, we now have the parameters of what we can build.
- A loop: repeating track and scenery code
- Length more than 600 meters and less than about 700 meters
- Tight curves at each end of about 20-meter radius
- Maybe some other more gentle curves to emulate the Trainz Dogbone
- Two spurs
- A station object, a freight house object, a road and a house object
- Miscellaneous other objects that make the route come alive; maybe some sounds?
Article and screen shots ©2006 Sanford Mace. All rights reserved.
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©2006 Sanford Mace. All rights reserved.