Under the ‘composite’ distribution system, many small depots with limited temperature control facilities were replaced by composite distribution centres (called regional distribution centres, RDCs), which can handle many products at several temperature ranges. The opportunity is to provide a cost effective daily delivery service to all stores. Typically, a composite distribution centre can handle over 60 million cases per year on a 15 acre site. The warehouse building comprises 25,000 square metres divided into three temperature zones: frozen ( 25°C), 2°C (chilled) and 12°C (semi ambient). Each distribution centre (DC) serves a group of between 100 and 140 retail stores. Delivery vehicles for composite depots can use insulated trailers divided into chambers by means of movable bulkheads so they can operate at different temperatures. Deliveries are made at agreed, scheduled times. Ambient goods such as cans and clothing are delivered through a separate grocery distribution network which relies on a stocked environment where orders are picked by store. This operation is complemented by a strategically located trunking station which operates a pick to zero operation for fast moving grocery on merchandise units that can be placed directly on the shop floor.