Contour Grading for Access Roads: Matching Proposed to Existing Topography

The Question

How to determine where finish contours meet existing contours on an access road grading plan?

Core Principle

Start with existing topographic map. Overlay proposed design. Match contour numbers (95 to 95, 98 to 98). Edges must blend via slopes (max 2:1) or walls. Cannot cross property lines (UBC: 2-ft setback).

Complexities

• Curbs/gutters/swales distort contours at slope/gulley intersections.
• Road above original grade creates “floating” contours.
• Drainage elements: points (swales) point uphill; crowns/berms point downhill.

Resources

• Time-Saver Standards for Landscape Architecture (McGraw-Hill)
• Site Engineering for Landscape Architects (AVI Publishing)
• Example: Flickr contour grading

Note

Hand-drafting is a dying art; CAD surface modeling dominates. Principles remain identical.