These subdivisions are in turn clustered in an area between Hillsboro and Beaverton just south of the new light rail line. When seen in the context of the larger area shown in Figure 16, there is another such cluster of subdivisions near northwest Hillsboro. These two clusters are in turn part of the Washington County cluster of development as seen from the scale of Metropolitan Portland and a twenty year time frame. The development of subdivisions absorb the capacity of access streets and sewers. Clusters of subdivisions absorb the capacity of collector and arterial streets and interceptor sewers.
Regional developments absorb the capacity of freeways and sewage treatment plants.
As the depth and breadth of our datasystem expand we will examine this explanation of urban development patterns further by testing sequences of infrastructure provision and subdivision. We can then more closely examine sequences of planned infrastructure announcements, vacant land sales, subdivisions, residential lot sales, building permits, and changes in improved land values. The methods used above to investigate custom built versus speculatively built subdivisions can be extended for these analyses. The combination of the visualization tools and statistical analysis of sequence yields interesting hypotheses about urban development patterns and means for testing them. We can test this claim on the empirical experience of Portland, as development proceeds and as we cumulate additional data.