- Awards and Recognition
- Annual Reports
- Barrier Aesthetics
- Blue Star Memorial Highways
- Classified Landscaped Freeways
- Community Identification
- Context Sensitive Solutions
- Erosion Control Toolbox
- Gateway Monuments
- Highway Planting
- Mission Bells
- Nonstandard Specification Info
- Policy, Manuals and Procedures
- Roadside Toolbox
- Safety Roadside Rest Area System
- Scenic Highways
- Standard Specifications and Plans
- Transportation Art
- Visual Impact Assessment Outlines
- Visual Impact Assessment Training
- Water Conservation
Erosion Control Toolbox
To Combine Specifications
Planning & Design
Improve Soil Health
- Soils Testing
- Local Topsoil
- Imported Topsoil
- Roughen Soil Surface
- Stepped Slopes
- Contour Grading and Slope Rounding
- Decompact Soil
- Soil Nutrients
- Incorporate Materials
Improve Soil Health & Provide Cover
Short Term Cover
Long Term Cover
Steep Slope Techniques
- Stepped Slope
- Cellular Confinement
- RECP Flap
- RECP Flap with Brush Layering
- RECP Wrap
- Soil Filled RSP
- Wire Blanket
- Wire Mesh Confinement
- Plant Selection
- TransPlant Application
- Noxious and Invasive Species
- Drill Seed
- Dry Seed
- Native Grass Sod
- Brush Layering
Low Impact Development
- Sidewalk Stormwater Planter
- Sidewalk Stormwater Tree Trench
- Parking Stormwater Planters
- Permeable Paving
- Additional Resources
Contour Grading and Slope Rounding
Images above illustrate slope rounding and contour grading proposed for Route 46 San Luis Obispo County between postmile 32.2 and 56.3
What is This Treatment?
Contour grading and slope rounding involves grading the project roadside with smooth, flowing contours that help integrate highway improvement within its surrounding environment. Concentrated water flows in graded valleys helps sustain vegetation in arid regions.
Besides helping make a highway facility compatible with its surroundings, this grading technique also helps reduce erosion and maintain water quality by breaking the slope into many smaller tributary areas dispersing runoff. Due to their higher moisture content, these focused drainage areas are better suited to supporting larger plants such as trees and shrubs than the planar slopes produced by rectilinear grading.
When to Use This Treatment?
- Consider using contour grading and slope rounding whenever permitted by the right of way limits.
- Typically used on cut slopes 2:1 and 3:1 (H:V) composed of rippable material. For specific maximum slope gradients, consult your geotechnical engineer.
- Comply with the guidance provided in the Highway Design Manual (HDM) Chapter 300, Topic 304.4 Contour Grading and Slope Rounding.
- Comply with the guidance for Slope Roughening/Terracing/Rounding/Stepping provided in Appendix A of the Caltrans Storm Water Quality Handbooks Project Planning and Design Guide.
Consider Using With:
- SSP 20-170 Local Topsoil
- SSP 20-040 Erosion Control (Hydroseed)
- SSP 20-055 Erosion Control (Compost Blanket)
Reduced stormwater runoff volume and velocity.
Improved infiltration rate.
Improved soil water holding capacity within sculpted valleys.
Improved potential for vigorous long term vegetation coverage.
- Topographic diversity supports a wider range of plant material.
- Reduces irrigation requirements by providing sheltered areas with higher moisture content that can be planted with higher moisture loving plant material such as trees and shrubs.
- Provides visual compatibility between highway facilities and their surrounding environment.
May increase the cost of earthwork activities.
Requires site accessibility by earthwork equipment.
- Use standard department Earthwork specifications.
Plans and Details:
- No Standard Plans or Details available.
- No pricing information is currently available for contour grading.
- Highway Design Manual (HDM) Chapter 300, Topic 304.4
- Caltrans Contour Grading Slope Rounding Webinar
- Schor, H. & Gray, D., 2007. “Landforming: An Environmental Approach to Hillside Development, Mine Reclamation and Watershed Restoration.” Published by John Wiley & Sons, Inc.