I thought that turnpikes were just 2 long trailers, be they 53's,48's or 45's.

My theory is that there is an inverse relationship between population density and the permitted length of combination vehicles.

On one hand you have urban New York which won't even allow 53's and on the other you have the intermountain west where you can pull 100- 110 ft of vehicle. At the extreme you have Australia where there is no length limit whatsoever.

 

Here are a couple of examples of "Rocky Mountain" sets where the 28 ft pup is the lead trailer:





This combination made up with the pup as the lead box is a bit on the rare side. Here in the Reno, Nevada area carriers that use this regularly are both Yellow and Conway. I've seen Matheson Fast Freight and Reddaway use this combination, but very rare.

Jimmy B