Bucket brigades at Anderson

Anderson Merchandising is the second-largest distributor of recorded music in the US; and they have achieved this by distributing exclusively to Wal-Mart.

Part of a
    bucket brigade

Figure 1: Bucket brigades, picking to paper from flow rack achieved a 20% increase in pick rates.

As is typical in high-volume distribution supporting retail, most of their labor is devoted to broken-case picking. Figure 1 shows half of one aisle, with about six pickers. (There are about as many on the half of the aisle not shown.) The pickers are operating as a bucket brigade, with the direction of material flow toward the viewer. A worker may pick several orders simultaneously.

Picking is from paper; there is no pick-to-light. Anderson is non-union and had no incentive scheme.

It was easy to convert to bucket brigades. Absolutely no changes were made to operations except to require the pickers to pass material according to the bucket brigade protocol.

We measured productivity before and after converting to bucket brigades and found a 20% increase in pick-rates and a 90% reduction in variance. In other words, their order-picking has become both more productive and more predictable, which makes it easier to manage.

We modified bucket brigades slightly to suit a special situation at Anderson, which was the intermittent appearance of huge orders. Most established Wal-Mart stores ordered large amounts; but whenever Anderson had to supply a newly-opened Wal-Mart, the order was huge.

The problem for bucket brigades was that a huge order backed-up any orders following it because bucket brigades forbid passing. The resolution was simple in this case: We required that, if a picker became blocked by the huge order, she must exchange her smaller order for the huge order. This meant that the faster picker, now freed of the huge order, could move ahead and everyone could continue to pick.

The huge order gradually "moved back" in the stream of orders; but all other orders maintained the sequence in which they were released and so arrived in proper sequence at the shipping dock. The huge order had a trailer to itself and so no harm was done in allowing it to lose its place in the order stream.