A prime example is Prologis’s new warehouse being built at the large International Park of Commerce project in Tracy, Calif. The building, which doesn’t yet have a tenant, will have 40-foot ceiling clearance that is taller than traditional warehouses, ample parking for workers and space to allow the easy movement of trucks loading and unloading cargo.Traditional warehouses are configured for replenishing retail stores, with items packed in pallets or at least large cases. This makes it impractical to store inventory in too many floor levels, because transporting pallets across multiple floors is not easy. However, in ecommerce, most packages have a small number of items, often just one. So a system that stores inventory in multiple floors and moves stuff across levels using conveyer belts, chutes, elevators, and other such machinery, can be very efficient.
This reduces the land area required for the physical warehouse building. The WSJ article also mentions the need for more space for transportation vehicles (both loading/unloading docks and parking spaces), which somewhat offsets the space reduction, although if smaller vans are used for fulfillment instead of large trucks then that can also be done in different floor levels.
As ecommerce retailers rush towards developing capability to fulfill orders very quickly, they need to build fulfillment facilities closer to big cities. This increases the cost of the land the warehouses are built on, so anything to reduce the amount of land needed is significant. I'm sure we're going to see more developments in ecommerce warehousing: one of the things I can think of are drive-through pickup windows, for customers themselves or third-party fulfillers like Instacart and Curbside.