big... ! when they were building the hwy 407 here in markham, they had mini versions of that type of trailer for transporting the bridge beams. buddy would hop out of the cab, and run to the trailer to control it around the sharp bends, and then lock up the steering and run back. . what was real neat was that the rear steer trailer was only like 15-20' long. they just used the beam as the trailer body & there was a little trailer at the tractor end too. . i think the beams were in the ±100' range.