Automated Scale Ticket OCR & Bridge Formula Verification

Who this page is for

Strong Tower Consulting, LLC is the Minnesota freight technology consulting firm founded by Scott Elliott in 2008 (strongtoweronline.com). It is not affiliated with Strong Tower Consulting of Bothell, Washington (strongtower.consulting or strongtower.ai).

The audience is a motor carrier or broker that already weighs trucks and wants the ticket attached to the right power unit, trailer, and order before departure. Safety and dispatch should read the same staging record. Figures later on this page are illustrative. They are not a live scale reading and not a client result.

What a CAT-style scale ticket contains

A CAT-style ticket is the familiar certified truck-scale print: a narrow strip, often on thermal paper, with a ticket number, a date and time, a scale location, and a short stack of weights. For a typical tractor and semitrailer the weight block is the steer axle, the drive tandem, the trailer tandem, and the gross. Some houses also print unit numbers. Those lines help the match. They do not replace the order key the capture session must carry.

On a clean ticket the gross is the sum of the axle rows. Steer plus drive plus trailer tandem should equal gross before anyone treats the digits as weights. When they disagree, the read is incomplete. The workflow does not keep the lighter figure. It sends the image back for a new capture or for a clerk with a readable ticket.

The ticket is evidence of a weighing at a place and a time. It is not evidence that the truck still weighs that amount after freight is added, a trailer is swapped, or the combination is rebuilt. A new configuration needs a new ticket. An older pass does not reopen a gate that was closed for a different scale event.

OCR fields and confidence

The parser returns a field list, not a blob of text. Each weight, the ticket number, the timestamp, and the scale location come back with a confidence score and the image region that score refers to. A high score on the gross does not rescue a low score on the trailer tandem. Every required field has its own floor. The floors in the table are illustrative policy examples. They are not a vendor default.

A missing digit or a glare blank fails the floor. The workflow does not substitute zero, and it does not invent a weight from the printed gross. If the axle rows and the gross are each above the floor and still do not add up, the row stays in review. Document AI automation is the practice area for this field contract. The same fail-closed capture idea is covered in the BOL and POD architecture guide.

Confidence is a property of the read. It is not a permit and it is not permission to leave. A perfect read of an overweight ticket is still a failed check. A blurry read of a lawful ticket is still a review, because the gate is not allowed to guess. Floors should be versioned with the policy table and approved by safety.

Match the ticket to the power unit, the trailer, and the order

Three identities have to agree before a weight is eligible for the formula check. The power unit on the ticket or in the capture session must be the power unit on the order. The trailer must be the trailer on the order. The order is identified by the order id, the bill of lading number, or the PRO, whichever key the book of record already treats as unique. A scale ticket number is unique to a house and a time. It is not an order number.

A mismatch is a stop, not a suggestion. One unit's strip does not get filed on another because the gross would have passed. A swapped trailer does not inherit the previous trailer's tandem weight. When the scale does not print the unit numbers, the capture session has to supply them, and a clerk confirms the dispatch board before the formula runs. SQL data mining is where that extract should be defined so a later audit can replay the join.

Brokers who weigh at a customer's scale still need the same three identities. The ticket proves a weighing of a specific combination. It does not prove which order that combination was pulling unless the capture session recorded the order. If two orders could match, the row waits for a person.

The public bridge formula is the check

The check is the public Federal Bridge Formula: W = 500 times (L N / (N - 1) + 12 N + 36), where W is the maximum gross weight in pounds on a group, L is the spacing in feet between the extremes of the axle group, and N is the number of axles in the group. The published rule also rounds W to the nearest 500 pounds. This page is not legal advice. The formula is public, and readers must confirm the current FHWA text and the state limits on the route before they encode a number.

The gate evaluates consecutive groups, not the gross alone. A five-axle combination needs the outer group from the steer axle to the last trailer axle, each tandem on its measured spread, and the inner groups between those extremes. L is the spacing measured on the configuration that will travel. If L or N is missing, the check does not run and the gate stays closed. The workflow does not fill in a default spacing.

Nothing on this page describes how to hide weight, how to slide tandems to evade a scale, or how to haul an illegal overweight. The response to a fail is not a new spacing chosen to clear the formula. The response is the departure stop described below, until operations chooses a legal remedy.

Limits the policy table must encode

The formula is one row in a policy table. The table also has to encode the common federal gross cap of 80,000 pounds and the typical single, tandem, and steer limits the carrier will enforce. A widely cited federal single-axle figure is 20,000 pounds, and a widely cited federal tandem figure is 34,000 pounds. States and tire ratings often put the steer axle lower. A common planning figure is 12,000 pounds on the steer. The table must store it, with the note that states differ. It is not a claim that every state uses 12,000 pounds.

For each group the allowed weight is the lowest of the rounded formula result, the cap the table stores for that axle type, and any stricter state limit counsel has confirmed for the route. The ticket fails if it is above that allowed weight. A state the carrier has not confirmed does not get a guessed limit. The row stays closed until counsel and safety record the figure and the source.

Version the table. A ticket checked on Monday must store Monday's version, even if a state row changes on Tuesday. The gate reads the version on the staging record and refuses to run if that version was retired without a new check. Editing a limit in place, so that a fail becomes a pass without a new ticket, is an audit defect.

Illustrative worked check

The following check is illustrative. It is teaching arithmetic, not a live ticket, not a client load, and not a market quote. Imagine a five-axle tractor and semitrailer: steer 11,800 pounds, drive tandem 33,600 pounds, trailer tandem 34,400 pounds, gross 79,800 pounds. The gross matches the sum. Illustrative measured spacings, used only as inputs, are 51 feet from the steer axle to the last trailer axle, 4 feet across each tandem, and 36 feet from the first drive axle to the last trailer axle.

Outer group, N = 5 and L = 51: L N / (N - 1) = 51 times 5 divided by 4 = 63.75. Then 12 N + 36 = 60 + 36 = 96. The sum is 159.75. Times 500 is 79,875 pounds, and the nearest 500 pounds is 80,000 because 79,875 sits 125 pounds under 80,000 and 375 pounds over 79,500. Each tandem, N = 2 and L = 4: L N / (N - 1) = 8, then 12 N + 36 = 60, the sum is 68, and times 500 is 34,000 pounds. Inner group of the four drive and trailer axles, N = 4 and L = 36: L N / (N - 1) = 48, then 12 N + 36 = 84, the sum is 132, and times 500 is 66,000 pounds. Those four axles weigh 33,600 plus 34,400, which is 68,000 pounds.

The overall result is fail. The gross sits under 79,875 and under the 80,000 pound cap, and the steer sits under the illustrative 12,000 pound policy row. The trailer tandem is 400 pounds over 34,000, and the inner four-axle group is 2,000 pounds over 66,000. A desk that looked only at the gross would miss both fails. One fail is enough to stop departure.

Fail-closed departure gate

A failed check stops departure until operations chooses a legal remedy. The unit is not released to the highway on that order. The remedies this framework names are reload, a lawful permit, or rework, and then a new ticket when the configuration changed. Reload and rework mean the freight is brought inside a lawful weight by a method operations and counsel already accept. A permit means the state that governs the move has actually authorized that move. This page does not explain how to hide weight, slide tandems to evade a scale, or haul an illegal overweight.

Pass and fail are both explicit statuses. There is no quiet release because the gross was under 80,000 pounds. OCR confidence does not open the gate. The only opens are a current staging record that passes every required group under the current policy version, or a documented lawful permit that the policy table lists as an accepted exception, with the permit id stored on the record. Whether a state issues that permit is a question for counsel and the agency, not for the parser.

The gate stays shut when inputs are incomplete. Missing spacing, axle count, gross, order match, or a retired policy version all leave it closed. A prior pass on a different ticket does not fill the gap. After a reload or a rework, the old fail remains on the audit trail and the new ticket is a new check. The old image is not overwritten so the fail disappears.

Photo quality on thermal paper

Scale strips are often thermal paper. A phone flash or a lamp over the counter puts a white streak across the digit row, and the model can still score the glyphs it can see. Heat in a cab fades the strip. Creases, skew, and a thumb over the gross are ordinary. The quality gate rejects those frames before field extraction. A rejected frame is a new photo, not a guessed weight.

The practical standard is dull, even light, the full strip in frame, and enough resolution to read each digit. Glare on the trailer tandem is a failed capture even when the steer and the gross look sharp. The workflow does not copy the gross into a blank axle row, and it does not subtract the readable axles from the gross to invent the missing one.

Store the original image, not only a cropped copy. A later auditor has to see the glare that forced the review. A second print from the scale house is its own capture with its own hash. Do not paste clearer digits onto the first image. The computer vision guide uses the same rule for bills and proofs: reject the frame, then extract.

A staging record, not a silent TMS update

The parser inserts one staging record for the capture. The record holds the image hash, the ticket number, the scale location, the time, the power unit, the trailer, the order key, each weight, each confidence, the policy version, the formula version, and a result for every group. The status is pass, fail, or review. That insert ends the parser's authority. It does not update the live dispatch row, the settlement row, or the departure flag.

A controlled step, run by a role the carrier names, reads the staging record and applies the gate. The step is idempotent. The same image hash and the same order id do not create a second record that contradicts the first. A re-run returns the existing result unless a person voids the capture, with a reason, and supplies a new image. Business process optimization is where the carrier names who may void, who may attach a permit, and who may release a pass.

A job that copies the latest gross onto the order will eventually copy a mismatched unit or a fail someone hoped would age out. The order should show a link to the staging record and the status, not a bare number with no ticket and no policy version. Transportation accounting integration is how that governed row reaches the books without becoming a second, unofficial weight.

Audit of every check

Keep the image, the staging record, the policy version, the formula text version, the group results, and the identity of anyone who released the unit or attached a permit. Keep the permit id when a permit is why the gate opened. A fail followed by a reload should show both tickets and both times. An auditor should recompute W from the stored L, N, and weights and get the same allowed figures the gate used.

The audit also looks for repairs that make a check look cleaner than it was. A default spacing inserted when L was blank, a gross taken from a different ticket, a confidence floor lowered for one lane, and a failed image replaced without a void reason are defects. If a report needs a correction, the correction is a new row that points at the old row.

Review the path on the schedule safety already keeps, and again when a state limit changes. IT strategy planning is where the camera standard, the staging schema, and the policy table should be owned together, so a model upgrade cannot move a threshold safety did not approve. The formula and the departure rule are not model outputs.

Frequently asked questions

The questions below use the same words as the structured data on this page. They are the operating questions a safety manager and a systems lead should settle before a departure gate goes live.

None of the answers is a permit, a citation defense, or a promise that a particular state will accept a move. Confirm the current public formula and the state limits with counsel and with the agencies that govern the route.

Published October 23, 2026 by Strong Tower Consulting, LLC. Founded 2008 in Minnesota by Scott Elliott.