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.