The bridge shuddered, delighted, as a short freight train rumbled across its span. It was a clear, warm sunny day, not hot enough to need expansion joints, but nice, overall. Felt good to get a little work in, it supposed.

The light changed for the road beneath it just as the last train car cleared. No caboose, the bridge noted. Those had gotten rare. Cars streamed underneath it; the sun shone...

And then it caught the telltale profile of an oblivious approaching box truck from a couple blocks away.

Work was over.

Now it was time for a little fun.