DTB Monthly

March 2026

March 2026 carried the same mechanism the quarter has been showing: mid-horizon revision activity outside the 72-hour zone.

Published May 05, 2026 · Framework TradeLanes DTB Monthly v1.1 · Status Operator-facing

1. Opening

Layer 1 · Headline · Opening Frame

March 2026 produced 5,921 CRW revision events across 751 voyages. 55.9% of those events arrived beyond T-7. The mass of schedule movement sat inside the planning horizon, not at the late-stage boundary the system is designed to catch.

A methodology note covering the carrier-terminal data pipeline artifact first identified in DTB Monthly Dec 2025 (MAEU at Norfolk's primary container terminal) appears in Section 4. The artifact remains under engineering review in this edition.

Two things were true in March. The aggregate story (median window moved from 136h to 129h) beside the voyage story (top-activity voyages recorded 92 or more revisions). The contradiction is the story.

2. The Mechanism

Layer 2 · Pattern · Terminal anchor

The mechanism is paired ERD and CY Cut activity - Sustained Churn. 49.1% of March 2026's voyages with movement showed both fields revising together (co-moving), the largest class in the dual-signal breakdown. 15.2% showed CY Cut activity alone, 18.6% ERD alone, 11.8% held flat, and only 5.2% showed the two fields moving in opposite directions. The failure mode is not the two signals diverging. It is both signals continuing to move together while the planning horizon closes.

USSAV Savannah carried 2 of the month's top-activity voyages. The terminal anchor is consistent with prior months even when the network-level distribution shifts.

The three-element read

Contradiction. The network median moved across March 2026's planning horizon - and 751 voyages produced 5,921 revision events. Both readings are true because the aggregate hides where the mechanism operates.

Operator implication. The plan committed at T-4w faced 55.9% of revision activity arriving between T-14 and T-7 - exactly the window where rail commits and drayage dispatch are being finalized.

Failure mode. Clustered revisions arrive mid-horizon. The window reshapes. Stability doesn't come. The commit deadline arrives. The exporter commits against the latest shape - which is overtaken by the next revision before the truck reaches the gate.

3. Bridge to Evidence

Layer 2 → Layer 3 · From claim to patterns

If mid-horizon Sustained Churn is the mechanism, three patterns must appear in the data:

1. Revision activity concentrated inside the planning horizon, not at its endpoints.
2. A non-trivial share of voyages with sustained instability rather than directional drift.
3. That share concentrating at specific terminals, not distributed across the network.

Here's what March 2026 showed.

4. Quantified Proof

Layer 3 · Three findings that anchor the mechanism

55.9% of March 2026 revision events arrived beyond T-7. The mass of schedule movement sat between T-14 and T-7 (25.5%) and beyond T-14 (30.4%). Only 26.4% of events landed inside T-3. This locates the mechanism outside the 72-hour boundary and inside the planning horizon.

Paired ERD and CY Cut activity is the dominant signature. 49.1% of voyages with movement showed both fields revising together. Only 5.2% showed the two fields moving in opposite directions. The mode is sustained, not divergent.

Volume sits at 5,921 events across 751 voyages. 25 distinct carriers, 10 U.S. ports, 403 distinct vessels. The activity is broad-based, not isolated to one carrier or one alliance.

5. The Illustrative Case

Layer 3 · The mechanism in one voyage

FELIXSTOWE 527E at USSAV Savannah (carrier ZIMU, departure March 31, 2026). 46 CRW revisions. Total absolute magnitude: 1,992 hours. Paired ERD and CY Cut activity: 23 ERD revisions, 23 CY Cut revisions across the same voyage. The terminal pushed the whole window forward as a single unit through 46 revisions.

This voyage carried roughly 43 hours of CRW motion per revision on average - the single-voyage signature of March 2026's mid-horizon Sustained Churn pattern. The exporter who committed drayage at T-4w against the published window committed against a plan the schedule had not finished drawing.

The window didn't break. It kept moving.

6. Concentration and Repeat Offenders

Part A - Concentration

Where Sustained Churn operated at scale in March 2026

USSAV Garden City - the mechanism in detail.

2 distinct carriers represented in the March 2026 USSAV concentration cluster. The signature is cross-carrier paired activity at one terminal.

Other concentration entries - USTIW Tacoma.

USORF - deferred pending methodology review.

7 MAEU vessels at Norfolk appear in March 2026's residual top-activity list by CY Cut activity. The CY Cut signature follows the same pipeline-artifact pattern first identified in DTB Monthly Dec 2025 - alternation between adjacent candidate timestamps independent of underlying terminal activity. These voyages are documented in the methodology note (Section 4) and are not used to support a Norfolk concentration finding in this edition. A concentration finding at Norfolk may be warranted once the underlying data can be validated independently.

Part B - Repeat Offenders

Prior-month qualifiers only · Temporal boundary rule

6 March 2026 vessels appeared in prior-month top-activity lists, qualifying as Repeat Offenders under the temporal boundary rule (qualification from prior months only):

• KINGSTON · 019E (ONEY) at USSAV Savannah - prior-month qualifier 2025-10
• ZIM VIRGINIA · 155E (ZIMU) at USSAV Savannah - prior-month qualifier 2025-10
• ONE BLUE JAY · 040W (ONEY) at USORF Norfolk - prior-month qualifier 2025-11
• EVER MAGIC · 1441-006W (EGLV) at USOAK Oakland - prior-month qualifier 2025-10
• KINGSTON · 019E (ONEY) at USORF Norfolk - prior-month qualifier 2025-10
• ZIM VIRGINIA · 155E (ZIMU) at USORF Norfolk - prior-month qualifier 2025-10

The repeat pattern is geographically consistent with this edition's concentration findings: 3 of 6 are at USORF Norfolk.

7. Decision and Cost

Part A - The Decision Shift

Layer 4 · Operator behavior change

The commit horizon is wrong.

Exporters committing drayage, rail, and appointment decisions at T-4w to T-2w faced a schedule that took its final shape between T-14 and T-7 in March 2026. 55.9% of revision events arrived beyond T-7. The schedule's information mass is mid-horizon, not late-horizon.

The decision shift: move the commit window inward where operational constraints allow. Defer the decision to the zone where the schedule has the highest information content - roughly T-7 to T-3 - even at the cost of tighter planning horizons.

Where the commit window can't move - and for many rail-dependent exports it structurally cannot - the alternative is to commit at T-4w but rebuild contingency at T-7. Treat T-7 as a mandatory replanning checkpoint, not an observational one.

Part B - Operational Cost Chain

Five steps from plan to cost - traced against FELIXSTOWE 527E

1. Plan. At T-4w, the exporter commits drayage against the published window for FELIXSTOWE 527E at USSAV Savannah. Rail slot booked. Driver scheduled. Trucking appointment reserved.
2. Churn. Through March 2026's mid-horizon, the terminal pushed ERD and CY Cut forward together across 46 revisions. Total absolute motion: 1,992 hours.
3. Pressure. Smaller paired corrections arrived alongside the larger pushes. Every check against the terminal returned a different gate window.
4. Commit. The commit deadline arrived. The driver was dispatched against the latest published window.
5. Cost. Driver wait time, container dwell, appointment rebooking - receipts of a plan made against a schedule that hadn't finished moving.

The cost cascade doesn't fail at step 5. It fails at step 4 - when the commit has to be made against a schedule still in motion. Steps 1 through 3 produce the failure. Step 5 receipts it.

Don't move step 5. Move step 4. Commit inward - where the schedule has resolved.

8. System Statement + Forward Hook

Layer 4 → Close

March 2026 produced 5,921 CRW revision events across 751 voyages. 55.9% arrived beyond T-7. The pattern is consistent with the Sustained Churn framing introduced in DTB Monthly Dec 2025 - paired mid-horizon revision activity that does not collapse into a stable plan.

The operator's problem isn't too many vessels at once. It is no stable point to act.

Next edition closes Q1 2026. The question for the quarter is whether mid-horizon Sustained Churn is the durable framing, or whether April's data shifts the pattern. The Garden City concentration is the test case.

TRADELANES · DTB MONTHLY · MARCH 2026

tradelanes.co

Methodology

Sustained Churn cohort definition. Voyages with paired ERD and CY Cut activity (co-moving) form the umbrella cohort under the v0.4 voyage-level pattern taxonomy. Sub-modes are named in the framework appendix. Classification thresholds are not published.

Carrier-terminal suppression. A pipeline-level artifact in CY Cut revisions for Maersk vessels at Norfolk's primary container terminal - first identified in DTB Monthly Dec 2025 - remains active in March 2026's data. 7 MAEU/USORF voyages appear in residual top-activity lists with CY Cut activity that does not reflect underlying terminal behavior. These voyages are excluded from concentration findings and Norfolk band assignments in this edition. A fuller treatment will appear once engineering review resolves the underlying data.

Cohort window. March 2026 U.S. departures with observable schedule revisions. 5,921 events across 751 voyages.