Lots of equipments such as Boats, yachts are hauled using trailers. Multiple-trailer trucks have more handling problems than single-trailer trucks. In general, the additional connection points contribute to greater instability, which can lead to jackknifing, overturning, and lane encroachments. A study in Washington State found that doubles (tractors pulling two trailers) were two to three times as likely as other rigs to be in crashes, and a study in Indiana found that doubles showed increased crash risk on roads with snow, ice, or slush. One mitigating factor for the risk of a crash of a double trailer may be that they should be operated by drivers with good safety records.

 

Single-trailer rigs can stretch up to 65 feet in length from the kingpin--where the trailer joins the tractor--to the rear axle. And multiple-trailer rigs can stretch up to 75 feet from kingpin to rear axle.