The following resources are provided as a reference by Bentley's Technical Support Group. 

Regression Analysis - Rail Learning Path

Video Clips

• Video: Import Existing Horizontal Rail Points from ASCII File
• Video: Create Sorted Horizontal Line from Regression Points
• Video: Convert Existing Rails to Regression Centerline
• Video: Create Horizontal Curvature Diagram
• Video: Horizontal Regression (Slew) Report
• Video: Horizontal Geometry Report
• Video: Add Point To Regression Line
• Video: Add A Line To Slew Calculation
• Video: Regression Line from Rails