A Study in Murphy's Law and Reverse Engineering!


On Saturday November 26, 2005 the Seattle Monorail cars collided, yes, the monorail cars collided. The story is when they were installing the tracks they allowed them to come together without the clearance necessary to pass, this was done to allow for the loading ramps to extend to the outer car. For 40 years they made sure the trains would never run at the same time. But one driver decided to leave early and the rest is history. We as engineering professionals know “It’s all about Murphy’s Law”.

I was hired by Jon Jacobson Engineers to help design and document the engineering. Dr. Jacobson was the engineer when there was a fire on the Blue Train and because of this experience was hired to do the engineering on both the Red and Blue cars. The damage was very extensive to both cars, and required massive rework. One problem was that quite a few of the doors were torn off. The original door manufacturers were contacted and could not provide the doors in the require time frame. So I was assigned to reverse engineer the doors.

We did not have original door drawings, but we had a couple of door installation drawings. Both of these drawings showed a slightly different configuration for the doors. These were paper drawings. Dr. Jacobson had the drawings scanned and converted to the DXF format. I was quite surprised at the accuracy that we got from the scan. I could actually use the graphics in my new design. I imported the the DXF data and proceeded to create the doors. Oh, yes, the drawing was first angle projection and in German!!

Since we didn’t have the door drawings we also had to do an extensive physical study of the doors. We disassembled one of the doors and I took the parts and started to work. There was a complex mechanical interface between the doors and the cars. The doors are operated by a pneumatic system. I created most of the components of the door in IRONCAD to start the mechanical design. Reverse engineering is basically two steps. First you create the basic configuration. Then you make sure the parts fit and provide the functionality and look for ways to enhance the original design, after all it was designed over 40 years ago.

This was a fun and interesting project. The renderings and drawings were generated in IRONCAD.

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