Electrified Pony Express on wheels may look interesting but it is not a practical solution for long haul cargo.

Using existing railroads to move trailers and local e-delivery truck units at each end on a 24-hrs/day basis would be more practical and would remove most of those long haul trucks from highways.

Another acceptable alternate solution may be with Nissan's bio-fuel FCs and a few batteries for acceleration and hills.

The oil companies and auto companies have depended a hundred years on fossil fuels for their profits and electric drive is very very disruptive to their ability to satisfy the Wall Street crooks with positive quick profit numbers. Their histories show they care less about what their products do to people or the Planet.
These factors are the nemesis to moving quickly to any other form of transportation unless they are forced to do so by Government. Attacking their bread and butter products, i.e., fossil fuel guzzling trucks, amounts to war.

The Republicans, backed by oil money, have already forced their candidate, Trump, to denounce electric drive and have directed him to embrace the continued use of fossil fuels by threats to not pay for his campaign using their oil money.

See Nikola Motor Company at https://nikolamotor.com/one

Todays Heavy Trucks get 5-6 mpg (http://www.forbes.com/sites/stevebanker/2015/06/01/new-heavy-truck-epa-regulations-to-require-increased-fuel-economy/#6e30da16131b)
So todays cost of fuel per hour is $22.15 @6 mpg.

If you want to make sense, as you declare, start with electrification of short haul trucks.

Roger Pham, since I'm trying to approach this from an economic rather than environmental view, the Supertrucks are worthy adversaries, and relatively equal in economic benefit/cost. This begs the question; why aren't Supertrucks taking over the market if they are so much cheaper to run? An answer to this would help me decide whether the Pony Express (or EHighway for that matter) is worthwhile pursuing. Perhaps it is because as Mr. Wilder mentions, natural gas is the most economic alternative at the moment?

EV trucks, I think, can only make over the road if they go with grid ties as they are running down the road.

The battery would have to be impossibly big for a tractor to make it in a long haul scenario, Its more of a weight / size issue in my mind. (if efficiencies are there, cost might not come into play.

Like others said, being able to drive point to point without much stopping or switching tractors is a big deal. If semis could go with swappable batteries the paradigm might change but again, the infrastructure is a challenge to implement. Cars are a personal space, not everyone views them as strict utility. Pony express might work for some companies. But owner operators are a big market, and it won't work for them. (I think its far fetched to say that people would be accepting of it) Battery swaps would be more logical.

Big cars, light duty trucks, and semi's, are neglected. I understand why we don't have any vehicle that tows that are primarily BEV, but hybridization should be goal. Taking advantage of the braking waste heat is the easiest way to improve efficiencies, also if LD trucks went FWD with a rear E axel, there could meet another 3-7% increase. Its just how they implement it.

No one really wants to stop on vacation/work towing a trailer every 100-200 miles to charge it for 30 mins(assuming huge break through in charger technology).

Autonomous trucks would be a game changer, especially if it included an autonomous rail yard.

Natural gas trucks are harder to implement, its a cryogenic fuel, and its not much more efficient. Its just cheaper than most alternatives because its abundant and its fairly easy to capture(it floats up). Truckers basically fuel up before a run, otherwise its wasted as the fuel climbs in temperature. I think LP is better but that's me. Both are much cleaner to burn than diesel and gasoline due to their shorter carbon chains.

Besides the infrastructure expense of having tractor-swapping stations spread all over the interstates, the Pony Express model requires you to purchase many more tractors for the same amount of hauling than currently required. If the tractors can recharge in 2 hours to be ready for the next truck needing to swap, and the next truck always arrives just in time, then you need at least 2X the number of tractors. Load balancing, slower charging and dead-ending issues would undoubtedly require a higher multiple. I don't see how you avoid big infrastructure/capital expenses with this model.

Sure, the Pony Express only ran for two years, but its demise was primarily caused by the telegraph. The Pony Express was closed two days after the telegraph connected California to Nebraska. I very much hope the Pony Express method of tractor swapping will meet the same fate, with some magic battery giving 1000 miles of range to electric long haul trucks. However in the meantime, tractor swapping may be a useful stopgap measure in electrifying long haul trucks. Since the profitability increases as the difference in cost between electricity and diesel widens, we will implement this first in countries such as the UK and Sweden. The UK because it has high diesel taxes and reasonable electricity rates, and Sweden because it has fairly high diesel prices and extremely low electricity rates. The US probably needs a carbon tax to make electrification of long haul trucks economically attractive, because then natural gas loses its cost advantages. Powering trucks with natural gas is an unfortunate environmental choice, since burning NG emits plenty of CO2, and the inevitable methane losses counter any CO2 gains over burning diesel. As to the infrastructure expense of Pony Express tractor swapping, it is much less than you might imagine (Opbrid makes charging stations you know), and the added expense of having 1.5X the number of tractors is actually not an expense. The extra tractors will be have the same mileage put on them, the fleet will simply last a couple years longer before needing replacement. If you compare tractor swapping to any other method of electrification of long haul trucks, it is by far the most cost effective. Plus, it meshes perfectly with driverless trucks, since a computer doesn't care how many times it stops. Pony Express tractor swapping can be implemented immediately, no new technology is needed. Of course, it favors large fleets, but so will driverless fleets. In a few years owner-operator will no longer exist as a business model.

I'm thinking this "Pony Express tractor swapping" could be used as a wedge for something more effective. Once a critical mass of electric trucks are on the road it will make more sense to electrify the highways so the time taken to swap tractors can be by-passed.

@C-88:

Yes, FC-PHEV long haul heavy trucks and intercity buses could use on-board FCs to keep batteries charged.

Near future clean bio-fuel FCs would have an advantage over current diesel units. The total range would be limited to the size of the ethanol tank.