PortEconomics ass. member Pierre Cariou - in collaboration with Figueirido de Olivera G. studied the efficiency of iron ore and coal ports in more than 15 countries, with their study published in the scholarly journal Maritime Policy and Management

Pierre and Figuerido used data envelopment analysis to asses the efficiency of 122 iron ore and coal ports in 2005. Estimates for 54 loading and 68 unloading ports show that the main source of inefficiency in bulk terminals is related to the scale. Results aggregated at a country level demonstrate that the national efficiency can be achieved either through a limited number of large ports or by combining smaller ports with complementary characteristics—national network effect.

You can download the study: de Oliveira, G. F., & Cariou, P. (2011). A DEA study of the efficiency of 122 iron ore and coal ports and of 15/17 countries in 2005. Maritime Policy & Management, 38(7), 727–743 @ the Journal webpage.