4.2.2 Preliminary Schematics-Stage

Preliminary Schematics-stage analysis is a medium-detail analysis applied to projects at a middle development stage. Per the HCM, Preliminary Schematics-stage analyses are “conducted to support planning decisions related to roadway design concept and scope and when alternatives analyses are performed.” Compared to a planning-stage analysis, the preliminary schematics-stage may have the project broken down into smaller components for individual analysis. Projects in the preliminary schematics-stage may also include more data that was not included in the planning-stage analysis.
Preliminary Schematics-stage analyses:
  • Are conducted for projects such as alternatives analyses, preliminary design, and existing intersection/corridor evaluation;
  • Answer key questions to determine scope and benefits of further study, if needed;
  • Use tools that may need more detail input;
  • May use tools that are deterministic (report same results, given same inputs) and macroscopic (evaluate traffic stream as compared to individual vehicles); and
  • May use tools that are stochastic (account for randomness) and mesoscopic (evaluates both traffic flows/streams and individual vehicles)