From the synthesis phase emerge design concepts that reflect an understanding of the constraints of the problem and that propose optimum solutions, given the many trade-offs that must be made. The designer is confronted with the resolution of many conflicting demands. For housing units there is an inherent conflict between pedestrian and vehicular traffic. If traffic flow is too fast or too heavy, it will hamper pedestrian crossing unless either traffic lights or pedestrian bridges are installed. Each of these solutions takes additional resources.
It is in the synthesis phase that the data gathered and the analysis of the problem must be translated into proposals for action. Prior to the complete development of the urban design plan, there are several preceding activities. The first component of the synthesis phase is the evolution of concepts that address the problem. In the initial phases, there may be a number of concepts proposed. There is usually more than one way to solve a particular set of problems. Concepts are followed by the development of schematic design proposals. These proposals are more specific in nature. Schematics are followed by preliminary plans.