The Geologically Improbable Railroad, Mountain Division is an indoor large scale railroad built in the basement of a mountain cabin in Green Valley Lake, CA. This railroad started in 1990 with a Bachmann Big Hauler set and grew from there.

I knew when I started this railroad that I was not going to be able to keep to a formal era so I dreamed up creation story for it. The railroad was a branch of a major railroad, the ATSF, that was cut off and forgotten by the mother railroad by some undefined calamity sometime in the late 19th century in the style of the "Petticoat Junction" railroad of TV fame. It continued with the equipment it had for years. Since there is an electric trolley line, it can't exist earlier than Frank Sprague's first electric trolly in 1888 or so. There is also gas mechanical equipment that didn't exist until the 1920's, hence the era the squishy "era" of about 1920.

Most of the motive power is steam and mostly Bachmann. Almost all of the rolling stock is Bachmann as well.

The railroad consists of three lines on three levels interconnected at a fairly complex interchange such that a train can get from any line to any other line without fouling the third line. The "inner" and "outer" lines can be interconnected with the scissors crossover into a "twice around" configuration. Branching off the crossover is a branch that climbs a 1 3/4 turn spiral inside a plaster mountain to the "upper" line which is really a loop to loop arrangement.

The outer line, which goes around the perimeter of the basement, has a 6 track switching yard, a small engine yard, several sidings and a wye. The inner line circles the town and has a passenger station siding, a hidden staging siding, a spur at a freight station, an industrial/mine siding and two reversing cutoffs. The inner line is a folded dog bone with about half of of the trackage hidden. The upper line contains another 4 track switching yard, two stub sidings, a passenger station siding, and two reversing loops. In the town, there is also a standalone loop to loop automatically operating trolley line that goes into and out of the town to a hidden holdover stop under the scenery.

I set this railroad up with two yards to allow a source and destination for manifest traffic. There are two passenger sidings, one on the inner level and one on the upper level. There are also several industry sidings, a freight station siding and a stockyard siding. Even though it was in the original plan, a mine siding and loading track has just recently been added. The "interchange" between the three lines is set up to all the steep grade in the spiral to be doubled as needed. This can be done from either the inner or outer lines without fouling the other line. There are five reversing features, two loops at the ends of the upper line, a wye on the outer line and two reversing cutoffs on the inner line. The inner line can be run loop to loop but it's operation is not automatic.

These features allow the line to be actually operated with a timetable type system but I have never deveoped a formal timetable or car card system to do it. Since this has been a single operator railroad since 1994, I just make up operations on the fly.

All of this track, about 400' including yards and sidings, is crammed into a 16' x 26' basement.

The layout is a work in progress, intended to be a never-ending project. All the track and wiring is in as is most of the hardshell and part of the scenery. I intend to be working on this one for many years to come.

Many construction photos are presented in the links below, but I also collected some of them into a QuickTime Slideshow.

• This version of Geologically Improbable Mountain is studded with 7 tunnels. A full spiral is enclosed within.
  
  
• Parts of all three lines, the interchange and the control panels are shown in this view.
  
  
• The interchange.
  
  
• A town site is under development. A dedicated trolley line serves the town.
  
  
• A six yard track serves the main line
  
  
• A small engine yard is adjacent to the main switching yard
  
  
• The "outer" loop punches right through the stairs to the basement
  
  
• A sample of GIRR, Mtn Division rolling stock
  
  
• The GIRR Mountain Division Equipment Roster 3 Jul 08
  
  
• GIRR Mountain Division Layout Diagrams and Configuration 28 Sep 08
  
  
• GIRR Mountain Division Early Versions 24 Oct 09
  
  
• GIRR Mountain Division Construction Photos
  
  
  • This is the location of the GIRR Mountain Division.
    
    
  • Sometimes you park in unusual locations
    
    
  • Construction of the GIRR Mountain Division began with a single wall bracket
    
    
  • The space between the workbench and the cabinets will soon become the main yard.
    
    
  • Initial framing went in quickly
    
    
  • The spiral was the first track laid is it determined the final elevations of the outer and upper levels
    
    
  • After the spiral was installed, a mountain was built around it
    
    
  • Tunnels were first cast over a wire frame with Hydrocal and paper towels so that the final tunnels would have depth
    
    
  • When the going gets tight, we employed some smaller workers
    
    
• GIRR Mountain Division Photos If you are a basically neat person, then the clutter in these photos might offend you.
  
  
• GIRR Mountain Division Structures 17 Aug 08
  
  
• GIRR Mountain Division Town Photos 17 Aug 08
  
  
• GIRR Mountain Division Scenery Updates 17 Jul 10
  
  
• GIRR Mountain Division Mine and Mine Train 20 Nov 09