You never store boxes unless you have to, you always reposition them (usually to Chicago, which is where most containers go to sit, be repaired, or scrapped) to reduce the dwell. The only time you ground a box (if you're storing it long-term, you usually ground it to free the chassis, which will have flat tires if it sits too long anyways) is during a downswing on freight. Look at the intermodal numbers from this year and you'll see things are a bit down across the board for domestic freight, but until you see containers on the ground they aren't being stored. More likely they are slowing the flow of MTs cycling back to the midwest. This sounds like an EMP specific problem too (which is NS owned), they might just be leveraging other RR assets to use as a trailer yard to ease capacity in the terminal.
The holiday freight was delivered in October, a little bit in early Nov. For the most part its already done with, but yes it does create a freight bubble.
There is plenty of outbound freight but not as much as inbound like you suggested. However, to say little to no outbound is far from reality (NS wouldn't run on train on just inbound loads, thats not how intermodal makes money, you gotta move about 50-60 loads over 600 miles each way to make money). Don't worry, with attractive spot rates they keep the train more than 50% loaded outbound... besides the EMP equipment is all leased or brokered freight, doesn't sound like the IMCs are participating in this scheme. You don't want to run a train of all empties for intermodal when you have plenty of outbound freight, just tack some onto the existing outbound service here and there, they'll trickle out eventually and you'll keep everything in the black.
The problem at Ayer is a simple geometry one -- not enough space to handle the freight... could be an RR induced problem too... if trains stack up in bunches and all show up at once, the pathetically small Ayer yard will be choked. Similarly, could be a driver problem... Always had issues getting drivers to move empties around, they only want to move loads and be done with it. It's an ongoing battle to keep things fluid. Good thing they are doing work at Ayer in the spring to release some pressure. Maybe all of EMPs contract guys decided to take extended vacations...
Never let your containers pile up at RDCs or warehouse (they typically don't go directly to stores) for more than a few days because they'll get 'lost'. Had some before that consignees decided to use as storage units and were moving to an off site yard... A container is a more valuable asset than a trailer in this day and age, but also keep in the mind the chassis it sits on is usually much more valued as that is what keeps the boxes actually moving besides just the train, and they are always in some kind of shortage.
Have a great holiday.
