Some producer markets are becoming assembly (or pre-storage) markets, thus also influencing trade patterns. The strategic role played by the regional transport system in supplying urban areas underlines the importance it needs to be given in the analysis and design of policy. According to the African Development Bank, it amounted to USD 8.6 billion in 2008 (Table 4.2). The ECOWAS Commission is more pessimistic and puts forward the figure of USD 7 billion for the same year.