Two Portable Tanks and a T-Only CDL
Dana has a Class A CDL with a T endorsement only; she has no N or H endorsement. Her dispatcher assigns her a run from a fertilizer plant to a farm supply depot. The power unit is a three-axle tractor. Behind it she will tow two flatbed trailers in a double-trailer combination. Each trailer carries one 600-gallon DOT portable tank designed for liquid transport; each tank is secured to its trailer with chains and hard lines. The tanks contain a non-hazardous liquid fertilizer. The aggregate capacity is 1,200 gallons, and each tank is over 119 gallons. The dispatcher tells Dana that because the tanks are portable and not built into the trailers, the N endorsement does not apply, and because the load is not hazardous, the T endorsement is the only one she needs. Dana has not pulled doubles in eight months. The route includes a 6% downgrade and a weigh station.
1. Identify each endorsement required for the exact combination described and state whether Dana's T-only CDL authorizes the run.
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Two endorsements are at issue. The T endorsement is required because she will tow two trailers in a double-trailer combination. The N endorsement is required because the vehicle meets the tank-vehicle definition: each portable tank has a rated capacity over 119 gallons, the aggregate rated capacity is 1,200 gallons (1,000 or more), and the tanks are designed to transport liquid and are attached to the vehicle for transport. The H endorsement is not required because the fertilizer is non-hazardous. Dana has T but not N, so her CDL does not authorize this run. She cannot legally drive it until she adds N or the configuration is changed so it is no longer a tank vehicle.
2. The dispatcher argues that portable tanks are not 'built in' and therefore do not trigger N. Evaluate that argument.
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The argument fails. The tank-vehicle definition does not require the tank to be permanently mounted or built into the trailer. It covers tanks temporarily attached to the vehicle or chassis if they are designed to transport liquids or gases, each over 119 gallons, with an aggregate capacity of 1,000 gallons or more. These are DOT portable tanks designed for liquid transport and chained to the trailers, so they count. The narrow exception is for an empty storage container that is not designed for transportation and is temporarily attached to a flatbed. That exception does not fit tanks marketed and used as portable transport tanks. The dispatcher is confusing 'portable' with 'not a tank vehicle.'
3. What if each tank were rated at 450 gallons instead of 600? How would the endorsement analysis change?
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The aggregate would be 900 gallons, which is below the 1,000-gallon aggregate threshold. Each tank would still be over 119 gallons, but the definition requires both an individual rating over 119 gallons and an aggregate rating of 1,000 gallons or more. So the combination would not be a tank vehicle for N purposes, assuming the tanks are not otherwise part of a tank vehicle and the load is non-hazardous. The T endorsement would still be required because she is still pulling two trailers. If the cargo were a hazardous material requiring placards, the H analysis would change separately, but the tank-vehicle N analysis would not.