Contents

  • Cover
  • Front matter
  • Introduction
  • Identifying and managing risk
    • Risk overview
    • Working smart and efficiently
    • Starting the job – be prepared
    • The job is not finished until it is signed-off
  • Basics
    • Roading terms
    • Basics about soil
  • Good construction
    • A well-constructed road
    • A well-constructed landing
  • Earthworks
    • The right machine for the task
    • Clearing and stripping
    • Cut and side cast construction
    • Cut and bench fill construction
    • Full bench construction with end-haul
    • Earthworks compaction
    • Landing construction
    • Forming road corners and in-bends
    • Final grading before metalling
    • Stabilising cut/fill slopes
  • Water control
    • Water control overview
    • Ditches
    • Road drainage culverts
    • Berms and cut-outs
    • Flumes
    • Silt traps and soak holes
    • Silt fences
    • Single culvert river crossings
    • Ford crossings
    • Bridges
  • Applying aggregate (metalling)
  • Repairs and maintenance
    • R&M overview
    • R&M common to new construction
    • R&M of road formation
    • R&M during harvesting operations
    • R&M of river crossings
  • Assisting loggers and harvesting rehab
    • Installing deadmen
    • Installing debris traps
    • Harvesting track rehabilitation (rehab)
    • Harvesting track rehabilitation – cut-outs
    • Landing rehab
  • Want to learn more?
  • Glossary

NZ Forest Road Engineering Manual: Operators Guide

  1.  ›
  2. Earthworks ›
  3. Forming road corners and in-bends
 

Forming road corners and in-bends

Poorly constructed corners and in-bends can often cause road access or safety issues.

  • The grade on the corner has been reduced to improve truck traction. On roads steeper than 12%, it is good practice to reduce grade on corners and intersections
  • The corner is wider to accommodate heavy vehicle off-tracking
  • The road has zero or negative superelevation on steep sections
  • This steep, narrow corner caused trucking issues
  • The corner is too tight for some trucks, causing them to cut the corner (see arrow)
  • Build switchbacks with a minimum curve radius of 14 m; 16 m is preferred
  • Extend pavement width to cater for trailers (about 4.5 m extra width)
  • The inside of the road is benched to improve sight distance to address safety concerns

Reduce road grade before, through and after steep corners and switch backs. If built incorrectly, they are hard to fix

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