Hence the next step is to build the evidence base to validate or challenge the problem/objective tree analysis. This involves gathering socio-economic, scientific, engineering, and financial data to analyze the problems identified and support the project outcomes and objectives. A review of studies that have been completed and information that is already available will lead to the identification of information gaps in terms of technical information and data. Besides validating or challenging the identified problems and objectives, data should also be gathered to verify the causal linkages and logic of the problem/objectives tree.
For example, imagine that a project concept calls for the construction of an embankment or sea wall or other infrastructure improvements. However, the information currently available does not lead to the identification of potential locations, or accurate hydrological modelling data may not be available to accurately define the parameters of designing the proposed infrastructure improvements. Therefore additional data may need to be gathered and further analysis and modelling will need to be completed.
Once the necessary data has been acquired and analyzed the project concept can be detailed with potential activities, outputs, and outcomes. A general cost estimate of the concept will also need to be prepared at this stage that can be used in future consultations with potential financiers. At this point a city should be able to answer the questions “what is the project going to do” and “how much is it going to cost.”