El Mongual Bridge Project - lifting the beams, part 2

Here we are, looking at the far end of the beam we're working to lift. You'll recall from the previous bridge post that we've already started building a tower under the other end of the beam. The front end loader has been moved, and is being connected to this end of the beam.

Of course, the logs which were used for rollers have to be taken out from under the beam.

The base for the second tower is carefully created, once again making certain that it is level and secure. Having the beam fall is the biggest concern of this job, and building an unstable tower would make this much more likely.

This tower is built up until it is taller than the previous tower.

You might notice, in these pictures, that Russell is able to lift the beam several feet at a time, while the workers are building beneath it, and you might wonder why he could only lift the beam a few inches at a time when it was still up on the hill where it was poured. The answer is a fun fact of physics, which Allen wanted me to be sure you knew. Think of an old-fashioned see saw, which might be a heavy wooden plank balanced across a log. If you tried to pick up the plank when it was lying flat on the ground (before it became part of the see saw), you'd probably have to use both hands to lift one end, and you might just barely be able to lift it. However, when the plank is balanced on the log in the middle, then you can lift one end of the plank quite easily, perhaps even with just one hand. That's because you're only trying to lift part of the weight of the plank, and because the other end of the plank is being pulled downward by gravity, which also helps make it easier for you to lift. At our bridge construction site, the towers are acting as the center log of the see saw, making it possible for the front end loader to lift an end of the beam much higher than it could previously do. It sure is handy to know about physics!

Now the guys have moved back to the first tower, and will make that one a few feet taller than the one they just worked on.

These huge, squared off logs, by the way, are from those trees which were mentioned in a previous post, which we cut down to use for this project. Some of the wood was left round, to use for rollers, and some was squared off for use in the towers.

I think you've probably got the back-and-forth process figured out now.

We're getting close.

The front end loader yanks one end all the way up!

With the front end loader moved to the other side of the river one last time, pieces from the tower which is no longer in use are put into place to raise the remaining tower higher.

Now we're really close!

Success! Now both beams are in place, and we can all say a prayer of gratitude and breathe a sigh of relief!