Ted, interesting information in the referenced thread. I wish that I had it before I did the layout design. It’s a bit late now. So I’ just trying to determine what can be done with the pretty much cast in concrete plan (with four and one half spacing).
Russell, one point I should note is that all of the pictures in my first posting were taken with the trains on the O-81 and O-72 tracks. My plan is to run the larger locomotives and cars on the O-108 and O-99 concentric curves. I was checking to see if it was feasible to stick with Atlas’s four and one half inch spacing. However, your reply prompted me to do some additional testing. The new tests were conducted with the Big Boy midway through the O-99 curve and additional freight and passenger cars and locomotives run on the O-108 curve.
During these tests, the Big Boy boiler was nudged as far into the curve as it could go. The only close problems occurred with the 21 inch K-Line Amtrak passenger car, Weaver’s Bradley NH passenger car and the Atlas 89’ 4” flat car. The clearance with the K-Line 21” car was very tight; the Weaver Bradley a tad better, but still close. The Atlas flat without load was a no problem, especially because the Big Boy running boards are well above the flatcar deck. Loads on the flat car made it more interesting. With an Atlas trailer on the flat, clearance was close, but adequate. The issue arose if the flatcar load extended beyond the edge of the flatcar, such as the missile launcher on the USMC tracked vehicle. There was plenty of clearance with Lionel 18” streamliner and scale proportioned heavyweight passenger cars.
The Lionel ATSF 2-10-10-2 and 2-8-8-4 AC-9 Yellowstone steamers passed by easily. I checked a Lionel AC6000, without issue. The clearance distance is aided by the fact that most diesel cabs are well away from the middle of the engine, and the walkways provide extra spacing (the diesel’s handrails are below the Big Boy’s running boards). A Lionel JLC GG-1 had plenty of clearance. The only locomotives which could be problematic are the middle unit on the MTH Coal Turbine and a MTH or Lionel Centipede (none of which have walkways).
My conclusions are that, other than 21” passenger cars, Atlas flats with wide loads, Atlas articulated auto carriers, MTH Coal Turbines, Centipedes and Big Boys, locomotives, passenger and freight cars should be able to pass a Big Boy safely on O-99 and O-108 concentric curves. I would note that you have to be sure that you do not undershoot the four and one half inch center to center spacing.
All of the attached pictures were taken with the Big Boy on the O-99 curve and the other pieces on the O-108 curve:
Big Boy and Articulated Automobile Carrier, USMC tracked vehicle missile launcher too wide, Dinky Toy 10-Ton Truck on Atlas 89' 4" flat, Big Boy and Atlas trailer on Atlas 89" 4' flat, DD35A passing Big Boy, Big Boy and K-Line 21' passenger car and Beaver Bradley NH passenger car and Big Boy
