I have never seen, or even heard of this before last week. We were headed down to Cape Cod for our church women's retreat and my friend told me this big truck-thing, it really looks like a locomotive engine, travels sideways and moves the brick wall. It is the divider for the carpool lane on the south end of Boston on I 93. They move it depending on the time of day for north or south. I thought it was pretty cool! I hope my son gets to see it some time.