Bowser Manufacturing is catering to the more modern modeler with this offering. It took me a while to figure out what it was when I first saw the photo but finally, after looking at it for a while, the trailer hitch gave it away. It's the unit for the first trailer in a RoadRailer train.
I'm not sure about the current status of RoadRailer today as I see more and more intermodal shipping containers on the rails but the whole concept of running modified trailers on the rails was revolutionary when it was introduced several years ago. Trailers equipped with some special modifications for "ridin' on the rails" were filled at the factory then pulled to the rail yard. There, they were assembled into trains by attaching some special wheels units that allowed them to be linked into a long chain. The unit shown above was first in line then a regular road diesel could latch on and haul these trailer trains wherever they needed to go.
Upon arrival, the trailers were placed on the ground and hauled to their destinations by a conventional tractor.
I still see RoadRailers on the NS line that travels through Fostoria so I know that they are still in use today. But by far, the special trailer has been pretty much replaced by the shipping container that is simply placed on a trailer frame then hauled to its destination from the nearest intermodal yard. That appears to be the direction that shipping is going today but we can't forget the contributions that RoadRailer made to the shipping industry when it was first introduced. A train that is made up of 60-80 of these trailers makes an interest looking sight along the rails. Perhaps the biggest drawback is that unlike container carrying cars, RoadRailers cannot be mixed with other rail carss; they are truly "unit trains."
For those interested in modeling RoadRailers, Bowser Manufacturing offers serveral different trailer types to allow you to make your own. Their web site for the roadRailer equipment is http://www.bowser-trains.com/hocars/roadrail/roadrail.htm
RoadRailer doesn't fit my middle 1950s era but for those of you modeling any time over the past 25-30 years, a string of these trailers would probably fit your pike.