The encyclopedia · Software & IT · Operational decision · 2022–2024
Ninja Van used a ham-sandwich theorem to make delivery zones fair
Ninja Van partitioned delivery districts so each driver carries an equal expected workload, using a topology theorem and shadow prices.
Ninja Van
the move
Ninja Van runs last-mile delivery across several dense Southeast Asian countries, and dividing cities by informal wards left some drivers overloaded, some half-empty, and some customers waiting far longer than others.
USC researchers applied the ham-sandwich theorem — a way of cutting space so two quantities are halved at once — to partition delivery areas into districts with equal expected workload, then added shadow prices to re-zone as demand fluctuated.
Implemented in a treatment area versus a control in November 2023, the maximum average work span was 6.6 percent lower, reducing delivery time per driver and the chance of overtime.
why it works
- Neighbourhood wards are unequal, so driver workload is unfair and unpredictable
- Balancing distance-to-depot and customer density equalizes expected work
- Shadow prices let zones adapt to spikes in demand like surge pricing
- Equal workload reduces overtime and improves service consistency
what transfers
For territory design, partition by expected work rather than by the map; a balanced zone makes wait times and driver hours fair and predictable.
what came after
The zoning work was shortlisted for the 2024 INFORMS Daniel H. Wagner Prize and honored as an outstanding paper at the 2024 INFORMS Annual Meeting. The approach generalizes to any territory design that must balance workload.
references
- How a Ham Sandwich Can Solve Our Package Delivery Problems
- Introduction: 2024 Daniel H. Wagner Prize for Excellence in the Practice of Advanced Analytics and Operations Research
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