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. Cut and bench fill construction
 

Cut and bench fill construction

Cut and bench fill construction is a standard method of constructing roads in moderate to steep hill country.

Diagram 2: Bench cut to contain downslope fill material
  • A bench or benches can help stabilise the road or landing fill slopes because they provide a more stable base for fill
  • Soil from the initial bench is side cast
  • Locate the bench(es) so that the earthworks cut and fill volumes are balanced
  • The bench is located near the toe of the fill for the section needing benching
  • The bench is level
  • The bench is wide enough for safe and efficient construction
  • The dozer (arrow) is stumping
  • The fill is contained on the bench
  • Stumps are keyed into the slope at the toe of the bench
  • Slash has been used to reduce erosion

When should cut and bench be used?

There is no rule as it depends on the site, however use benches on slopes:

  • That are too steep for side cast construction
  • That are between about 40 to 70% but less depending on soil type. The recommended fill slope for most soils is 65%
  • Where there are known stability issues.
  • A bench was built because the slope was too steep for side cast construction
  • The fill was compacted in layers to increase fill strength
  • The bench contains all the earthwork fill
  • The edge of the bench is visible, which shows it was not over filled
  • A lack of benching and poor fill compaction led to these significant failures

If the bench is full, stop. Find a new contained and stable place for the fill. Also, if subsurface water is hit, stop. Talk to your supervisor about drainage

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