4. Conclusion
Urban infrastructure investments are typically strategic and longterm in nature. The benefits and costs of such investments are distributed spatially; therefore, they affect various stakeholders differently. Moreover, multiple, often conflicting and incommensurate, evaluation aspects are at stake for assessing the merits of the potential alternatives. A prototype GIS-based, Multicriteria Spatial Decision Support System (MC-SDSS) called MCPUIS (Multicriteria Planning of Urban Infrastructure Systems) has been developed for providing assistance to planners in the evaluation process. The primary functions of MCPUIS are: SRDD (storage, retrieval, and display of data); IOE (investment option evaluation); IOCS (investment option comparison and selection); and CISA (communication/interaction with the system and sensitivity analysis). The various capabilities of MCPUIS were demonstrated with a case study from the City of Coimbra, Portugal, which motivated the development of this system. MCPUIS was used to evaluate and compare four investment options to expand the water supply network to serve a proposed 77 hectare development on the city's edge. Ten different criteria were explicitly considered to compare and evaluate the 4 alternative courses of action. This evaluation process is facilitated by the GIS component of MCPUIS. MCPUIS incorporates three MCDAmethods (SAW, TOPSIS, and ELECTRE I) to help the DMs to compare and evaluate the alternatives. The sensitivity analysis function of MCPUIS revealed that the results obtained in the Coimbra case study were rather robust.