Supply Chain Action Points
Read this first — the conclusion, and the moves to make:
- By July 31, get a written weekly allocation from your rail provider and a written weekly commitment from your drayage carrier for the same lane, and plan on the lower of the two numbers, because that is your real capacity.
- Count loaded and empty boxes on the ground at your Mexico ramp on the same day each week for four weeks, and if empties pass 15% of the stack, add evacuation before you accept any new volume.
- Put a chassis commitment in writing, with a daily minimum and a substitution clause, before you accept any volume increase above 20%.
- Re-quote every door-delivery promise into or out of Mexico with a three-day buffer on the rail leg for the next 60 days, and move the promise date rather than the cargo when the buffer is gone.
- For the next two AAR prints, track the four-week moving average instead of the single week, and only change your capacity plan if the four-week figure moves more than 5%.
AAR data for the week ending July 18 showed Mexican railroads moving 14,408 intermodal units, up 53.0% year-on-year, and 13,058 carloads, up 12.2%. North American combined weekly traffic rose 3.6% to 710,760 units, with intermodal up 6.3% - signaling nearshoring-driven volume shifts toward Mexico.
The Analysis
Laredo is where the number turns into a truck. The Association of American Railroads counted 14,408 intermodal units on Mexican railroads in the week ending July 18, 53.0% above the same week a year earlier, plus 13,058 carloads, up 12.2%. All of North America moved 710,760 units that week, up 3.6%, with intermodal up 6.3%.
Fifty-three percent is not a train problem. A train is the cheapest thing in that chain to add, because a railroad can put on a second section once the tonnage justifies it. The scarce items sit at both ends: a chassis under the box, a tractor to pull it through the gate, a slot on the bridge, a door standing open at the receiving plant. Growth of this size lands on the road, not on the steel.
If you move anything into or out of Mexico this quarter, walk your own chain backwards this week, from the plant door to the ramp. The volume is already booked. The trucks are not.
Put the arithmetic next to the headline before you do anything with it. At a 53.0% gain, 14,408 units implies a base near 9,417, so the increase is roughly 4,991 boxes. The continental gain for that week is 3.6% of 710,760, about 25,600 units. Mexico's intermodal jump therefore accounts for something close to a fifth of the total weekly increase while sitting on about 1.3% of the base. The carload line behaves the same way: 13,058 at plus 12.2% is a base near 11,638 and an increase near 1,420 cars. Those figures are derived off rounded reported numbers, and I am showing the work so you can argue with it.
What actually moved, in physical terms. Nearshoring is not a slogan, it is a plant opening on the Bajío and a supplier two borders away deciding that the box now rides the rail instead of the water. That is why the intermodal line and the carload line split so hard, 53.0% against 12.2%. Intermodal means containers, and a container needs a chassis and a drayage tractor at each end of the rail leg. Carload means auto racks, tank cars, covered hoppers, and those need a private siding at the plant, which takes years and money to build but then moves tonnage with no truck per unit attached. A corridor growing its container share is a corridor pushing its bottleneck off the rail network and onto the road, and the road is the piece nobody forecasts.
Who feels it first. A large third-party provider with a contracted drayage fleet, its own chassis pool and a yard near the border will swallow a 50% week and barely blink, because it bought that flexibility in a soft market two years ago. A mid-size importer buying door delivery into Monterrey gets the volume without the flexibility: the rate holds, the transit does not. A plant taking components on a fixed line-side schedule is exposed the day the ramp runs out of ground slots, because a box that cannot be grounded cannot be pulled. An exporter shipping northbound out of Mexico is exposed in a different place, since all the empties generated by this southbound flood have to go somewhere and the cheapest somewhere is the same stack your export box needs. Bulk shippers on carload service, and anyone whose Asia sourcing still runs through a West Coast port, can treat this as somebody else's week.
The weekly print is a lagging indicator by construction. What you will feel arrives in a sequence, and the sequence matters more than any single date. The lift and the grounding at the ramp go first, because a terminal has a fixed number of ground slots and a box waiting for a chassis is sitting in one. Chassis goes second, and that shortage always looks sudden even when it has been building for a month. Gate appointments go third, and by then your drayage carrier is quietly choosing which customers to serve first. The plant door goes last, and that is the only one your customer can see. Six weeks is the realistic lag between a week like this one and a service failure at the receiving end, which puts the pressure squarely into the fourth quarter.
Here is the part the table does not carry. Intermodal growth is a two-way physical obligation: every loaded box that comes in has to go out, loaded or empty, and the empty is what quietly eats the ramp. A corridor taking 50% more containers inbound is also taking 50% more empties outbound or stacking them, and stacking them burns ground slots the next loaded train needs. Nobody publishes that number and it binds before the track ever does. The percentage also hides its own base. A 53% week on 9,417 boxes is a real signal about direction and a useless capacity plan. Half the value of a number like this lies in knowing what it does not license you to do, and it does not license you to sign a volume commitment you cannot dray.
Run a small account on it, with my assumptions on the table. Your program moves 60 FEU a week into Mexico, you own no chassis, and your drayage carrier runs three and a half turns per tractor per day. At the reported run rate the corridor handles 2,058 boxes a day, which is 14,408 divided by seven. Suppose a tenth of that gets pushed off the ramp and onto the road in a bad week: 206 boxes, a move at each end, 412 tractor moves a day, and at three and a half turns that is 118 tractors that have to exist that morning.
Your own share of the squeeze is three trucks. Whether those three exist is not your decision, it is the corridor's, which is exactly why you want your drayage contract to name a substitution clause rather than a rate. The turns figure is mine and not from the article, and it is the one I would argue about hardest, because a border dray is not a three-and-a-half-turn day.
The trap is a door-delivery quote built on a rail transit that assumes the ramp works. Most weeks it does. The week it does not, you are short a chassis, a gate slot and a plant appointment at the same time, and the penalty clauses in your sales contract do not care which one broke first. The other trap is reading one week as a trend and buying capacity you will have forgotten about by October. Neither mistake costs much in a normal month. Both cost plenty in the same month.
So do the cheap thing today. Call the ramp, ask how many empties are on the ground, and ask what the gate appointment lead time was last Monday against this Monday. Two numbers, one phone call, and you will know more about your fourth quarter than the AAR table will ever tell you. The table reports what moved. The ramp tells you what is about to stop.
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