ArcObjects

A library of software components that make up the foundation of ArcGIS.  This library is referenced in Visual Studio for development of the GIS-specific functions that make the Curvature Extension work.

Circular Arc

A curved line that is a section of a circle, with two vertices, one situated at each endpoint.  The Curvature Extension, using ArcObjects, creates a circular arc based the user-defined curve.  The radius of the circular arc is then used to derive the curve classification.

Curve Classification (or Curve Class)

A designation (A - F) assigned to a curve based on its radius.  A curve class of A indicates a broader curve, while a curve class of F indicates a sharper curve.

Curve Direction

The digitized direction of the curve in the route system.

HPMS

Highway Performance Monitoring System.  A  report to the Federal Highway Administration (FHWA) using the General Interest Roadway Data and other data to describe public road conditions and performance.

HPMS Feature

A record from the HPMS GIS layer that represents an HPMS sample.

Route System

For the Curvature Extension, a GIS layer of roads used to derive curve classification.