Mill Creek Central
Trestle Tower Construction I
A construction company would build the trestle by first doing all the foundations, then erect the towers, than install the beams, etc. The folks who volunteer at MCC are multitalented but none are structural engineers and none of us have undertaken a similar project. We decided to erect one tower first to make sure we liked the design and that we were actually able to erect it.
We decided to start with the third tower from the north end which is about 20.3 feet tall. (We initially though that tower 3 would be the tallest. However, after the foundation for tower 4 was poured we found that it will be about 6 inches taller then number 3.) Tower 3 is in the flat part of the valley (we later recognized how nice this was when working on the foundations of the towers on the steep north slope). We figured that if we could erect #3 , the rest would be easy (or at least easier).
This is the top of tower #3. The two 4 inch channels closest to the camera are the caps on which the beams will rest. Below the channels is a pair of short panels only 6 inches high with the bracing oriented horizontally. Next is a pair of 5 foot high panels orientated with the bracing vertical. Further down, the next pair of 5 foot panels has the bracing horizontal, then a pair with the bracing vertical. The bottom 5 feet of the tower is best seen in the next photo.
The bottom 5 foot panel was the correct length but had bracing only
horizontally. The ends of the panel had 1 inch long stubs of 2.62 inch OD tubes
that were intended to fit into the next panel. The lower 6 inches was cut off
both panels and the pieces reattached with the braces orientated
vertically and with the stubs inside the tubes at the joints. Note that
both ends of the tower have short pieces of panel with the bracing running
90 degrees to the adjacent panels. This orientation assures that the
towers are stable squares.
The foundation for tower number 3 was being constructed at the same time the tower was being finished and painted. The photo above shows the foundation for the 4 leg core which was made first.
This is the entire 8 leg foundation with the base channels in place ready for the tower to be set in place.
The photo above shows Dick moving the core tower from the assembly area to the tower site.
Check out the Constructing Towers II - Status page where we'll be posting photos of progress on the towers.