Turnpike Doubles
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Turnpike Doubles, Doubles and Triples, are trucking industry slang for what is known as "Tandem Trailer Operation". Tandem trailers are usually large hauling trailers connected with a single axle, wheeled connecting device known as a dolly.
The purpose of tandem operation is to allow trucks to carry two or more trailers bound for separate destinations. Shipping companies like UPS or FedEx, for example, use tandem trailers to "relay" trailers loaded with ground packages across the country.
In the United States, all states regulate the use of tandem trailer operations. Most states restrict operation of tandem trailers to interstates and specific routes, as they are inherently more difficult to control than a single tractor-trailer unit in an emergency situation and in adverse conditions.
Some states limit the length of trailers used in tandem to 28' in length. Most single trailers are 40-50' in length.
In more sparsely populated areas of western states, triple trailer operations (triples) are sometimes allowed. Also, some states allow the tandem operation of trailers longer than 28'.
Source: Don Corman, Former Trailer Fleet Supervisor, United Parcel Service, NNE
