The most sustainable urban development strategy proposed by our group is that of "infill", which proposes to convert unused spaces (such as empty parking lots or abandoned warehouses) in an urban core to residential uses. This increases population density, and has a host of positive side effects: with more people on the street coming and going, the vibrancy of the neighbourhood is increased, while at the same time crime is reduced; commute-to-work trips are reduced (with a typically higher job-density in the core); and, non-work trips are also reduced, with increased proximity to shopping and entertainment.

Cameron Churchill has been doing PhD research to develop a prototype decision support system (DSS), which will aid in the sustainable retrofit/infill of urban areas within existing communities. Ultimately, it is anticipated that the associated software will be used to design the layout of buildings as well as the hard and soft infrastructure needed to successfully complete each project. The DSS is being programmed using ArcView's internal language Avenue, and uses design rules based on sustainability principles in order to develop the layout of urban infill developments.

In order to create sustainable communities it is imperative that existing infrastructure within the urban boundary is fully utilized. A simple definition of infrastructure, is that it is the basic support framework of an organization. Within communities, the associated municipal infrastructure may be categorized as either hard or soft. Hard infrastructure consists of the physical aspects maintained by the public sector that are needed by the populace to carry out their daily routines. Hard infrastructure includes, but is not limited to, roads, sidewalks, water lines, and sewers. Soft infrastructure consists of the services, or buildings in which they are contained, provided by the public sector. Policing, schools and hospitals are examples of soft infrastructure. The methodology for the prototype application follows three stages that require either database information or user-provided information. The first step is to determine the capacity of the existing infrastructure for the development site. The next step is to prompt the user for information concerning target density, building composition of the site (residential, retail�), amount of open space, location of amenities, etc. With this information the program then uses the existing infrastructure as a guide for the placement of new infrastructure, if required. The final stage of the program focuses on the siting of any new buildings. The siting of new buildings is guided by the layout of the infrastructure that occurred in the previous stage of the program. If the placement of the buildings is not satisfactory (i.e. if it counters some design rules) then the program loops back and repositions the new infrastructure. This continues until a design is created which satisfies all of the rules programmed into the model.

This software will be useful in both the public and private sector. With an increasing interest in sustainable urban development and a tightening of budgets, many municipalities are looking at ways to increase urban density and decrease infrastructure expenditures. The benefits of urban infill development have many local governments taking stock of the existing land within their urban boundaries and exploring policy initiatives that will ease the building approval process. Models that can provide decision- makers with information on how to maximize the use of available land and infrastructure will be very useful for long term strategic planning. The benefits of the decision support system to private consulting firms may also be substantial. Private consulting firms could use the model to quickly design a number of layouts for their clients and provide them with a visual depiction of each. Finally the use of the software will help to promote the concepts of sustainability through its built-in assumptions and design rules.