Do Sewer Extension Plans affect Urban Development? A Multiagent Simulation

A multiagent simulation model is used to assess the impact on single-family residential development patterns of plans for size, location, and timing of sewer line extensions, policies for extension timing, and of responses to these plans and policies by landowners and developers. The simulation constructs the sewer network over time in relation to the sewerage provider's plans, to the construction of sewers and housing in previous periods, and to the expectations of landowners and developers regarding plans. In comparing the temporal and spatial patterns produced by the simulation, we found: (1) scenario 3 (early extensions not allowed), which was the historical policy in the study area, most closely replicated the historical development pattern; (2) the location of single-family residential development was not constrained by the capacity of the sewer network, but was constrained by the timing policy of sewer expansion; and (3) the developers could afford to pay for early sewer expansion, when allowed, on the basis of expected revenues from single-family residential development. The model succeeded in incorporating multiagent behaviors of landowners and developers sufficient to compare different sewer-expansion policies.