Contents

  • Cover
  • Front matter
  • Preface
  • Scope, purpose and use
  • 1. Terminology, economic analysis, risk management
    • 1.1 Terminology
    • 1.2 Economic analysis
    • 1.3 Understanding risk
  • 2. Regulations, consents and approvals
    • 2.1 National Environmental Standards for Plantation Forestry (NES-PF)
    • 2.2 Heritage New Zealand Pouhere Taonga
    • 2.3 The Health and Safety at Work Act
    • 2.4 NZ Transport Agency approval for access onto state highways
    • 2.5 District council approval for access onto council roads
  • 3. Planning for roads
    • 3.1 Road classes
    • 3.2 Arterial roads
    • 3.3 Secondary roads
    • 3.4 Spur roads
    • 3.5 Establishment tracks
    • 3.6 Spatial information
    • 3.7 Initial field work
    • 3.8 Manual design method: Stepping out a roadline on a topo
    • 3.9 Running a grade line in the field
    • 3.10 Full road design
    • 3.11 Working with road survey data
    • 3.12 Geometric road design
    • 3.13 Curve widening
    • 3.14 Horizontal alignment
    • 3.15 Vertical alignment
    • 3.16 Calculating the safe stopping distance
    • 3.17 Setting out the roadline
  • 4. Planning for landings
    • 4.1 Common landing layouts
    • 4.2 Landing planning considerations
  • 5. Road and landing construction
    • 5.1 Soil and rock properties
    • 5.2 Managing adverse environmental effects
    • 5.3 Marking clearing widths
    • 5.4 Roadline salvage
    • 5.5 Daylighting
    • 5.6 Road formation
    • 5.7 Drainage control during earthwork construction
    • 5.8 Earthwork machinery
    • 5.9 Estimating machinery production
    • 5.10 Stabilising cut and fill slopes during construction
  • 6. Pavement design, subgrade preparation, pavement construction
    • 6.1 Traffic loading
    • 6.2 Evaluating subgrade properties
    • 6.3 Determining pavement depth
    • 6.4 Pavement material properties
    • 6.5 Compaction of subgrade and pavement
    • 6.6 Compaction equipment
    • 6.7 Pavement construction
    • 6.8 Weak subgrades
    • 6.9 Chemical stabilisation of pavement or subgrade
  • 7. Erosion, sediment and slash control structures
    • 7.1 Ditches
    • 7.2 Cut-outs
    • 7.3 Berms
    • 7.4 Drainage culverts
    • 7.5 Flumes
    • 7.6 Sediment traps and soak holes
    • 7.7 Silt fences
    • 7.8 Sediment retention ponds
    • 7.9 Debris traps
  • 8. River crossings
    • 8.1 Fish passage
    • 8.2 Selecting the location and crossing type
    • 8.3 Fords
    • 8.4 Temporary river crossings
    • 8.5 Single culvert river crossings
    • 8.6 Battery culvert river crossings
    • 8.7 Drift deck river crossings
    • 8.8 Single span bridge river crossings
    • 8.9 Prediction of flood flows, and sizing culverts
  • 9. Road maintenance, repairs and upgrades
    • 9.1 Maintenance programme
    • 9.2 Economic evaluation of road maintenance projects
    • 9.3 Managing maintenance requirements
    • 9.4 Commonly used maintenance machinery
    • 9.5 Road surface maintenance
    • 9.6 Road foundation maintenance
    • 9.7 Landing rehabilitation and decommissioning
    • 9.8 Roadside vegetation maintenance
    • 9.9 Erosion and sediment control structure maintenance
    • 9.10 River crossing maintenance
  • Forest road engineering terminology
  • References
  • Websites, resources, databases

NZ Forest Road Engineering Manual

  1.  ›
  2. 3. Planning for roads ›
  3. 3.10 Full road design
 

3.10 Full road design

Consider full road design, especially where the road grade is approaching maximum limits, terrain is steep, and where other factors need careful operational planning.A key step is deciding whether a full road design is required. A full road design can be time-consuming and challenging due to the surveying requirements, detailed design work, the laying out of the pegs in the field, and the need for road construction operators who can follow the plans.

A full road design provides detailed plans for road and skid construction. At any point on the proposed infrastructure, the location and earthwork details around quantities of cut or fill, and specifics like cut slope height and the location of the toe of the fill, are known. In order to get this level of detail, the base information needs to be precise, otherwise the plans will not be accurate. Larger roading projects will typically be a combination of sections laid out directly in the field, with full design for only the more challenging segments, such as those with extensive earthmoving, where it cuts across steep terrain, or where switchbacks are required.

Advantages of undertaking a full geometric road design include:

  • The cost of road construction is likely to be reduced, because alternatives can be evaluated and the optimum design selected
  • There is greater reliability that the required road width will be achieved and the maximum gradient limits on the road will not be exceeded in the final road construction
  • The earthworks volumes can be predicted in advance, so the cost of construction can be estimated with better accuracy and reliability
  • The height of batter slopes can be predicted in advance for consent purposes
  • Better set-out information can be provided to the construction crew or contractor
  • Better decisions can be made as to whether a road is feasible in marginal locations
  • The design software can assist in minimising cut and fill depths
  • Where the road is designed and pegged accurately, a corridor can be marked to fell only the necessary trees, thereby minimising the number of roadline trees to be felled. For example, this may be important in areas that are susceptible to windthrow.

Full road design is best done by those who have planned the approximate road and landing locations. They will have the big picture view of what they want to achieve and, having walked the terrain, a good sense of where the potential construction challenges lie.

Designing roads requires competent technical skills. If these are not available in-house, then contract the work out to a professional.

Prev page Next page
Forest Owners Association

© 2023 New Zealand Forest Owners Association

Website by RS