The Big Dig Tour / Tunnel Construction 3K. M. Peterson
Here's a transporter moving one of the steel girders. They are taking it back out of the tunnel to be reused or recyled. You can imagine, from the scale of the workers walking next to this machine, the weight of the payload. This had very large tires that are clearly carrying a great load - and the thing was moving at a slow walking pace. This is looking back out towards the area that we'd previously passed through.