Subject: Why do dump trucks have long tow bars separating front and rear containers

In Western Washington there are many dump trucks with 2 containers. The 
front part is a regular dump truck but they pull a second container behind 
them. The tow bar between the two is telescopic and can extend probably 
30ft. Why would they not want to use the shortest tow bar possible to get 
the best turning radius? What is the reason for the variable length tow 
bar? We have pondered this for years and have several theories but would 
like a definitive answer please. Thank you.

Re: Why do dump trucks have long tow bars separating front and rear containers