Ring Residential

The historic 'ring' structure of industrial and manufacturing-centric urbanization, with residential around an employment core is caused by the need for transportation access. The core forms around essential transportation infrastructure--ports, rivers, railways, highway interchanges. Access to transportation is an economic necessity, and are capable of 'outbidding' competing land uses.  At the edge, 'outbid' residential uses locate. Because residential uses require more land area per person than industrial uses, they eventually come to 'ring' the industrial uses, impairing their expansion potential.