> For the complete documentation index, see [llms.txt](https://docs.openbrim.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.openbrim.org/templates/spliced-i-girder-bridge-workflow/geometric-criteria-spig.md). # Geometric Criteria \[SPIG] Requirements the bridge has to satisfy because of where it is, rather than because of what it carries. They are checked against the site geometry, not against a load combination, so they can be answered as soon as the geometry exists and long before an analysis runs. Today this section covers vertical clearance, in two objects that are used together: **Clearance Zone** * The region a clearance is measured over: the roadway, track, channel or path the structure crosses. It carries the region polygon, the surface the clearance is measured up from, and which objects are in scope. **Vertical Clearance Check** * The requirement measured over one or more zones. It finds the smallest clearance in each region, reports where that minimum occurs and what caused it, and passes or fails against the clearance you require. Splitting them this way means an interim and a final requirement over the same crossing share one region by construction, instead of relying on two rows being kept in step by hand. --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation by asking a question. Perform an HTTP GET request on the following URL with the `ask` and `goal` query parameters: ``` GET https://docs.openbrim.org/templates/spliced-i-girder-bridge-workflow/geometric-criteria-spig.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is what the user is ultimately trying to achieve, the reason they need the answer. Sharing it helps GitBook give you a better, more relevant answer. A goal is most helpful when it describes the outcome the user wants rather than restating the question. For example, with `ask=how do I create an API token`, a goal like `automate deployments from our CI pipeline` lets GitBook tailor the answer to that use case. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.