Commuting and metropolitan structure. Changes in Bilbao Metropolitan Area 1980-2001

The evolution of urban hierarchical structure of the metropolitan area of Bilbao is analysed during the period 1980-2001, using commuting data. The socioeconomic transformations of this period could be denoted under the brand of "postfordist transition" in which dramatic changes take place in demographic and economic structures, along with commuting patterns in metropolitan areas. Some authors suggest that, after this transition, a new polycentric structure or centres emerged in substitution of previous monocentric structure. In order to analyse the commuting data, a set of techniques is used here: nodal structure of links between places, distance decay parameters, and entropy indexes. Despite of the great increase of commuting during this period, both inside and outside of the metropolitan area, one conclusion of this article is that no polycentric structure takes place. The structure of four sub-centres organizing a second level of sub-areas is identified using the techniques mentioned above, sub-centres that were emerging in the early 1980'. The four sub-areas have different economic and residential functions. In addition, the primacy of Bilbao intensifies in terms of attracting outside employment.