Existing and potential problems, possible solutions and community development plans are examined. The end result of the planning process is a conceptual route described by classification, the type and location of accesses, the speed to design for, and the projected traffic volumes. Specific needs regarding lanes and interchanges, and cyclist and pedestrian accommodations are also established. In preliminary design, planning moves from a conceptual route to a more specific route after identifying a number of possible alignments. Essentially, everything completed in the planning design stage is taken to the next level and refined so realistic project cost estimates can be made, and the proposed route and highway can be geometrically designed on paper.
Preliminary design includes identifying property requirements, and environmental and social impacts.
Properties next to the proposed route are assessed for their influence on the route design and construction. Mitigation and compensation options are explored. The functional design stage takes the preliminary design information and hones it, with results from alignment surveys and geotechnical investigations, to a precise geometric representation on which the final detailed design will be based. Soil studies are carried out to assess potential construction challenges. Wet and soft soils require a deeper foundation for road construction.