Modifiable areal unit problem (MAUP) effects on traffic analysis zones (TAZ) delineation

Transportation analysis is typically thought as one kind of spatial analysis. A major point of departure in understanding problems is the recognition that spatial analysis has some limitations and impediments. Among them, modifiable areal units and boundary problems are indirectly or directly related to transportation planning analysis through the design of traffic analysis zones (TAZ). The modifiable boundary and the scale issues all should be given specific attention during the predetermination of TAZ because of the effects these factors exert on statistical and mathematical of spatial pattern (MAUP). The results obtained from the study of spatial data are not independent of the scale and the aggregation affects implicit in the choice of zonal boundaries. The delineation of zonal boundaries of TAZs has a direct impact on the reality and accuracy of the results obtained from transportation forecasting models. In this article, the MAUP effects over the TAZ delineation and the transportation assignment models are measured and analyzed using different grids (in size, and origin location). This analysis was developed building an application integrated in commercial GIS software and using a case study (Lisbon Metropolitan Area, AML) to test its implementability and performance. The results reveal the conflict between statistical and geographic precision, and its relationship with the loss of information in the traffic assignment step of the transportation forecasting models.