The Bridge

We need a bridge to connect the farms to the city. The grade crossing has been installed as well as some abutments. What I want to copy is this:

I have no idea as to the build date, but probably early 1900s. It connected a park once owned by the Horne family in Pittsburgh -- the same folks who owned the Horne's Department Store chain. The picture was taken after Ivan tore through the area in 2004. If you look closely, you can see debris against the left side of the deck, in fact, the center deck has been spring sideways about 4 feet by the rush of the water. The span length was about 60 feet. Some beams were under the floor, and three steel cables dipped down to provide the suspension on each side. It was demolished about 6 months after the photos were taken.

I'm thinking about four H columns (Plastruct), some wire (Clover House 285 stranded cable) and cedar (Garden Texture).

Here's the deck:


You might notice the four holes in the tops of each H column. The suspension wires will be threaded through these. You can also see the brass pins that hold the side rails, and planking of the deck, to the stringers underneath. And, yes, the bridge will be 2 inches higher at one end.

The cables have been strung. Their shadows against the white background make it seem like more than one in each place. Not so.

Bridge is in place. H columns were shoved down into pockets of mortar box. Likewise, the tensioning rods that come off of the tops of the columns. The wires will need to be tightened in a few days after things get accustomed to the weather. If you look at the underside of the stringers, you might see the heads of brass pins. The wires are fixed to the tops of the columns, then threaded down thru the hole in the stringer, around the pin, up again and then to the opposite end of the bridge. If I twist the pins a turn or two, it should tighten up the wires. (At least that's the theory!)

So, that's the project. Not very much time or material required in construction, and it makes (in my humble opinion) a somewhat unusual structure.

Note:  Well, it sort-of worked as planned. First mistake was I put a strip of foam board under the decking. This caused the planks to rot prematurely. Second error was planting the columns in mortar mix. Frost heave actually snapped one of them off. Final goof was not having a better way to keep the cables taught. I think we fixed these errors in the 2015 rebuild.