Red Sea detour dataset - maccus.fr investigation, November 6, 2026
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Source: IMF PortWatch, Daily Chokepoints Data (daily ship transits and total cargo
capacity per maritime chokepoint, estimated from AIS vessel-tracking signals; IMF with
the University of Oxford). https://portwatch.imf.org/pages/data-and-methodology
Data retrieved November 6, 2026; coverage 2019-01-01 to 2026-10-25.

Files
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raw-daily-transits/*.tsv : the daily series as pulled, one file per chokepoint. Columns:
  date, year, month, day, n_total, n_container, n_tanker, n_dry_bulk, n_general_cargo,
  n_roro, n_cargo, capacity, capacity_container, capacity_tanker.
  n_* = ship counts per day; capacity_* = cargo-carrying capacity in deadweight tonnes (DWT) per day.
monthly_chokepoints.csv       : monthly mean of n_total and capacity per chokepoint (the chart data).
chokepoints_now_vs_baseline.csv : per chokepoint, 2023 baseline vs the latest 30 days, with percent change.
summary.json                  : full computed statistics (baseline, October 2026, latest 30 days, break date,
                                detour cross-check). Includes the Strait of Hormuz with an exclusion note.

Method
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Baseline = daily mean, January 1 to October 31, 2023 (the last full pre-attack stretch; Houthi attacks on
Red Sea shipping began in November 2023). "Now" = the latest 30 complete days, September 26 to October 25, 2026.
Percent change = (now mean - baseline mean) / baseline mean, for ship counts and for cargo capacity.

Note on the Strait of Hormuz
----------------------------
Hormuz is EXCLUDED from the article's chart, table and headline numbers (kept in summary.json for the record).
Its PortWatch series reads about 70 to 105 ships a day through February 2026, then drops to about 3 to 13 a day
from March 2026, with no real-world event to explain it. That pattern is a change in the data's coverage of that
chokepoint, not a change in traffic, so it is not used.

These are AIS-based estimates, suitable for measuring CHANGE over time, not official canal counts.
Prepared by MACCUS (maccus.fr). The underlying data is IMF PortWatch; see the source link above.
