I keep seeing contract specs push for about 22 short ton coils; they fit under the 80,000 lb U.S. truck GVW once you net out tractor/trailer tare, which cuts lifts and freight touches. Trivia question for the ops brains here: was that trucking cap the real origin of the coil-weight norm, or did railcar loading rules from the 1970s drive it — and does anyone have a hard number on the handling cost delta per ton between 18 and 24?
In our service center, 20–22 ST was driven by both: one coil kept us under FHWA’s 80k on a 5‑axle and the same size let us load five in a 100‑ton coil car under the old 263k GRL (Truck Size and Weight - FHWA Freight Management and Operations). Small caveat: in Michigan/permitted lanes we’ve run 24–26 ST, but C‑hooks and OD clearances become the real limit, as @railrat will attest. Keeps the driver happy and the crane op’s blood pressure down.
But we targeted about 21.5 ST masters because one coil + gear kept a 5-axle under the “80,000 lb GVW” and, just as important, our 25-ton overheads/C-hooks could single-pick them without derate grief. If you chase 24 ST for rail efficiency, watch crane reach and OD; I’ve had to split lifts, , or rejig slitting just to stay inside hook charts. FHWA basics: https://ops.fhwa.dot.gov/freight/policy/rules_regs/weight/.
Quick data point: we standardized around 21.8 ST because the extra 300–500 lb of chains, bunks, and tarps will push you over “80,000 lb GVW” when the tractor shows up heavy. Rail-side, that size also kept us under older AAR blocking thresholds so we didn’t add another layer of cribbing. @e_jameson58 is right it’s a mix, but bridge-law axle splits drove it more for us — anything north of about 22 ST meant sliding gear to chase weights, which wastes time, .