Source Material…
Category: Structure, Diorama

Genre: Real World

Source: City of Chicago Public Transit System CTA

The Project…
Scale: 1:87 (HO Scale)

Size: Spread out across a broad area

Material: 3D printed parts and Laser cut acrylic

Approach: Completely Custom!

Software:

Autodesk Inventor
Autodesk AutoCAD

Specialized Tools: Laser Cutter, 3D Service Bureau

This is not actually the first time that I have designed and built a replica of Chicago's CTA. SMARTT was the model railroad contractor for the new Chicago Museum of Science (MSI) HO layout in 2002-2003. Part of the job was a model of downtown Chicago, and it required a replica of the elevated CTA train line. The design of this elevated support structure fell to me, and I spent a lot of time examining the extensive photos I was provided as well as whatever I could gather on the internet.

At the time, we had the parts laser cut in acrylic from my design, then our staff assembled them. The viewing distance is not close as the layout has a glass barrier and most of the tracks run further away through the buildings. As a result, stacked layers and quality paint were fine for that project. The new project, destined for a private collection, would be seen from as close as a foot away, with no barriers.

Customizations:

For this new CTA, technology had progressed in the decade since the MSI design, so we decided that the 3D printing technology available would give us incredible fidelity, as well as minute detail including hundreds of rivets per part that are only 0.015" each. I designed about a dozen or so different interchangeable components from the dimensions given to me, based on that extensive earlier research. Eventually, what we produced was a "Chicago EL Construction Kit" for our in-house use. Additionally, some joiner beams and plates that linked the supports were individually designed using Autodesk Inventor's parametric feature and these were also 3D printed.

The SMARTT staff assembled, painted, and installed functional track on the Elevated CTA that was then installed on the larger layout, producing a functional two-track replica. Later, I and a colleague designed stations that replicated several real world CTA stops to complete the set.

People who helped with this project: The SMARTT model making staff