The US army currently uses an APC called Stryker which weights about 19 Tons. It has 2 crew and carries 9 soldiers. The Arvus Lighter in Into the Storm says it'll carry 12 people or equivalent in cargo. That's less than 1.5 tons even if those are pretty big people carrying quite a bit of kit. So it's basically a flying minibus.
The Halo Barge on the other hand is a mass hauler. It can carry 40 people or 40 tonnes of cargo. Quite how that equates I don't know. So it might be able to carry two (relatively small) APC's. Probably not 2 Chimaeras or Rhinos. The permitted gross weight of an articulated lorry in the UK is about 44 tons. That's the type of lorry they use to deliver food to supermarkets.
I am having difficulty seeing either of these vehicles as realistic cargo haulers. Should they not be significantly larger in order to supply ships which have tens of thousands of men aboard?
Here's some info about the old warhorse the Hercules transport plane:
"Cargo Compartment - The C-130 can carry more than 42,000 pounds (19,051kg) of cargo. Rollers in the floor of the cargo compartment enable quick and easy handling of cargo pallets and can be removed to leave a flat surface, if needed. Five 463L pallets (plus a ramp pallet for baggage) may be loaded onto the aircraft through the hydraulically-operated main loading ramp/door assembly located in the rear of the aircraft. The ramp can also be lowered to the ground for loading and unloading of wheeled vehicles. Tie-down fittings for securing cargo are located throughout the compartment.
In its personnel carrier role, the C-130 can accommodate 92 combat troops or 64 fully-equipped paratroopers on side-facing, webbed seats. For aeromedical evacuations, it can carry 74 litter patients and two medical attendants.
From 10 August 1990 to the cease-fire, Air Force C-130s flew 46,500 sorties and moved more than 209,000 people and 300,000 tons of supplies"
The Arvus in my mind equates to a Ford Transit van or 2 ton lorry. The Halo Barge is a mere articulated lorry (the size capable of carrying a shipping container for instance). Surely the Imperium of Man would rapidly tire of such relatively small vehicles for equipping such large ships? Not to mention that you couldn't fit a tank in either of those. The British Armys Challenger 2 tank weights about 70 tons. I see no reason the Imperiums tanks would be any smaller or lighter.
As it stands a Rogue Trader wanting to land a battallion of 1,200 Imperial Guard would end up making 30 trips in Halo Barges to drop his men. That wouldn't include any support vehicles or personnel, armoured personnel carriers, rations, extra ammo and so on.
I'm afraid I couldn't find an article that quoted the consumable supplies a modern army needs on a daily basis but I'd be willing to bet it's quite a lot.
There have to be larger vehicles than this available else the Imperial Guard simply can't operate. Are there any mentioned in the fluff? Does anyone recall if Arvus Lighters or Halo Barges are noted as shifting tanks and the like?