Shipping lines are increasingly relying on schedule buffers, which involve increasing transit times, to manage ongoing network disruptions. A direct byproduct of this operational strategy is an elevated volume of early vessel arrivals. These early arrivals introduce “negative delay” into the global average vessel delay metric, which softens the reported severity of delays and obscures the true magnitude of network friction.
To measure this impact, Sea‑Intelligence evaluates the Schedule Padding Index (SPI) alongside the total number of early arrivals. A negative SPI value indicates the artificial addition of schedule buffers, which corresponds directly with a relatively higher number of early vessel arrivals.
During the pre‑pandemic baseline spanning 2012‑2019, the global SPI averaged +0.06 days. During this time‑period, early arrivals represented a mere 1.9% of global deep‑sea traffic, averaging 219 vessels per month. This dynamic shifted dramatically during the pandemic recovery in 2022, where the yearly average SPI plummeted to ‑0.20 days and early arrivals skyrocketed to an average of 716 vessels per month, representing 6.9% of all global arrivals.
This reliance on structural buffering has persisted into 2026, as shipping lines attempt to absorb the operational strain caused by prolonged Red Sea and Strait of Hormuz diversions. Through early 2026, the SPI has averaged ‑0.14 days, keeping early vessel arrivals highly elevated at an average of 486 vessels each month.
