Under Connecticut General Statue 14-262, the maximum legal length of the semi-trailer portion of a tractor-trailer combination is 48 feet. When “legal length” is cited, it means the maximum length that can be operated without a permit. Whether a particular load requires a permit because of oversize or overweight concerns is further defined under the 14-270 section of the CGS. The law under CGS 14-270-1 specifically defines the length of a vehicle (trailer) as the “total longitudinal dimension of any vehicle or combination of vehicles, including the load, or load holding device thereon.”
What this means is that any trailer and its load exceeding 48 feet cannot move without a permit. Technically, a one-inch “overhang” on the back of a 48-foot trailer requires a permit. Conversely, if you had a 40-foot trailer and 8 feet of overhang, the trailer and load would be legal because you did not exceed the 48-foot maximum. Naturally, you would have to light and flag the overhang according to State and Federal regulations, but the trailer and load itself would not be illegal.
The same logic is applied to straight trucks. The maximum length of “truck and load” is 45 feet. Any combination of truck and load that does not exceed 45 feet from front to back can travel without a permit.
You cannot obtain a permit for any truck or trailer exceeding the maximum legal lengths if the load being carried can be broken down. For example, a 50-foot beam that is bolted together in the middle to give it the length would not be given a permit because it could be separated into two 25-foot pieces that could easily be carried on the back of a 48-foot trailer.
There are some exceptions. Truck-trailers and tractor-trailers carrying utility poles can carry a 50-foot pole provided the overall length including the poles does not exceed 80 feet.
There are also some exceptions for 53-foot trailers. Why can a 53-trailer be operated without a permit when a 48-foot trailer with 1-foot overhang is illegal without a permit? Because 53-footers operate under the authority of CGS 14-262 with some very specific restrictions. The maximum allowable measurement from the center of the kingpin to the center of the rear-most axle in contact with the road cannot exceed 43 feet. The 43-foot measurement is critical: We estimate that 99% of the 53-foot violations involve an improper kingpin measurement. There are also route restrictions on where these trailers can travel (although the list of restricted routes gets shorter each year), and they are allowed to travel only 1 mile from the allowed routes for pick-up, delivery, repair, food, etc.