Foundational Logistics Knowledge: Flows, Functions, and Cost Trade-offs
The core model
Foundational logistics is the study of moving and storing goods to meet customer requirements at acceptable cost. A candidate must be fluent in the seven functional areas (customer service, demand planning, inventory, transportation, warehousing, order processing, and reverse flows) and in the three flows that run through them: physical product, information, and cash. Information flow is usually the cheapest lever and the fastest to change, which is why questions often reward the answer that improves visibility before adding capacity.
Cost trade-offs
The central exam concept is that logistics costs are interdependent. Freight consolidation lowers transportation cost but raises inventory and handling cost; faster modes cut inventory carrying cost but raise freight spend; more warehouses shorten delivery distance but add safety stock and facility cost. Total cost thinking, not minimizing any single line item, is the right frame. Know the components of carrying cost (capital, storage, risk, obsolescence) and that carrying cost is usually expressed as a percentage of inventory value per year.
Traps to expect
- Confusing warehousing (holding) with inventory management (deciding how much and when).
- Treating order cycle time as the same as transit time; the cycle includes order entry, processing, picking, and delivery.
- Assuming the cheapest mode is cheapest overall; service failures create backorders and expediting.
- Mixing up push (forecast-driven) and pull (demand-driven) systems.
Rule of thumb
Use the square-root law for safety stock: combining N stocking locations into one reduces total safety stock roughly by the square root of N. Four locations consolidated to one implies about half the safety stock, all else equal. Use this to sanity-check answers about network consolidation.
Worked example
A firm ships 40 orders per week at 500 each. Adding a consolidation step cuts freight 15 percent but adds one day of cycle time. Freight saving is 0.15 x 40 x 500 = 3,000 per week; weigh that against the value of a day of delay before declaring the change beneficial.