Do you think the push for twin 33-foot trailers is dead? It was two years ago, when the idea was squelched by members of Congress on safety grounds. But it’s been revived by some of the same interests that backed it then, primarily less-than-truckload carriers and shippers who argue that twin 33s would boost productivity over the current double 28-foot pups.

Revival might be riding on enthusiasm over President Trump’s pro-business beliefs and his promise to improve America’s infrastructure. On Feb. 1, Fred Smith, chairman of FedEx, testified in favor of twin 33s before a House committee, arguing that the same amount of LTL freight can be carried by fewer trucks. Gross weight would be the same and so would stopping distances; and limited experience with double 33s shows that they’re more stable and therefore safer.

FedEx has joined a new group, Americans for Modern Transportation, that’s promoting the idea. It’s composed of other LTL carriers, including UPS, plus shippers and retail companies, like Amazon. A predecessor organization, the Coalition for Efficient and Responsible Transportation, seems to have gone dormant since the twin-33s idea was shot down.

We know of no new legislation that would legalize the longer rigs, but the Truckload Carriers Association wants to kill the idea before it finds more strength. TCA’s president, John Lyboldt, last week wrote a letter to heads of Congressional committees arguing that allowing twin 33s would be a mistake. He said that truckload shippers will want to send their goods in two 33s instead of a single 53-foot van. They’ll see it simply as 13 more feet of cargo space.

But it’s not that simple, Lyboldt said in his letter. Truckload carriers would have to switch their fleets to 33-foot vans and alter operations. This would be tremendously expensive, similar to conversions in the 1980s and ‘90s from 45-foot vans to 48s and then to 53s. Most carriers then got nothing in return for their investments, because shippers expanded their idea of a “truckload” to what fit into the longer and longer trailers and paid little if any more in freight rates.

And, whereas single 53s are backed into loading docks, a pair of 33s would have to be broken down and then backed individually into docks, Lyboldt noted. Drivers would have to be trained for this. Beyond that, we can add converter dollies and changing from tandem-rear-axle sleeper-cab tractors to single-axle types with sleepers, which don't have much resale value.

As for operations, LTL carriers manage doubles and triples with multi-door terminals and dedicated lot space for separating and assembling the rigs.But much truckload freight travels directly from suppliers to consignees, bypassing terminals, so shippers and receivers would have to accommodate the additional maneuvering and equipment parking. How many of them would spend the money for that? Much more likely, motor carriers would be expected to set up special lots for this purpose.

Now, it is possible to build converter dollies that would lock a set of double trailers into a single unit that could then be reversed into docks. A small company in Washington State designed such a dolly back in the ‘80s. It was a modified C-dolly with double drawbars, says Gary Gaussoin of Silver Eagle Manufacturing. Its wheels caster-steered to minimize tire scrub during maneuvering. Trailer noses needed doors and ramps to pass cargo through from the lead trailer to the rear one and onto the dock, and vice-versa for loading.

But imagine backing a 66-foot trailer into some of the tight quarters that a 53 now just barely fits. The concept didn’t catch on then, and neither might the idea of twin 33s for truckload freight now. But for LTL freight, it seems to have an overwhelming number of positives. Let's see what happens.