A Manual for the Planning, Design and Construction of Forest Roads in Steep Terrain













Table of Contents


FAO - Food and Agriculture Organization of the United Nations

1998

This publication aims to give guidance on the design, layout and construction of forest roads in hilly terrain. It is intended to show best practice, including detailed descriptions of the surveying and construction techniques encouraged by the FAO.

The manual is based primarily on work done by Dr Rudolph Heinrich and Dr Otto Sedlack in preparing guidance for road work in Bhutan. Information was also obtained from the FAO/ILO/ECE Seminar on Environmentally Forest Roads held in Sinaia, Romania in 1996. The chapter on excavator built roads is based on the study carried out in Austria in 1997 by Joachim and it is hoped that this manual will help forest managers and practitioners with practical advice to meet the problems they will face in their operations.

Without road access most of the production of a forest would not be available. The construction of a forest road has the most potential of any forest harvesting operation to cause damage to the amenity and environment of the forest and, yet, is a most essential part of the strategic and tactical harvesting and other forest operations.

It is the need to fit these two contrary requirements that are the core of any forest road manual. It as necessary to ensure that all of the elements which go into the successful combination of

a road which is right for the harvesting operation;
a road which is capable of safely carrying the haulage traffic;
a road which does not interfere with the natural drainage patterns
a road which does not damage the landscape
a road which takes account of the flora and fauna;
a road which can be satisfactorily and economically maintained are included.

To do this requires an input from those involved with the preparation and implementation of the strategic and tactical plans for the forest area. They will include specialists in forest planning, landscape, conservation, harvesting, and engineering and may have additional input from fishing, game and soil specialists where required.

All of these people are experts in their own field, but unless they understand the reasons for the views of others, the various inputs could be counterproductive and result in a less than optimum solution.

It is the purpose of this manual for those who specialise in road building, to make sure that the principles of good road design and construction are paramount, but to take on board the need to have

good landscape design road drainage design that deals adequately with demands of erosion prevention and fishing requirements, but does not compromise the absolute need to drain the road effectively

road embankments and cuts which allow harvesting to take place without hindrance but which remain structurally stable cleared road widths which are minimal consistent with good road design and the ability if the sun and wind to reach the road to assist in drying

the possibility of using the construction of the road to enhance the conservation environment.

The change in soil structure arising from road building allows the growth of species which require that soil and the light arising from the tree felling on the roadline. Wildlife can also be encouraged with the changes in vegetation at the road edge. Good quality roads can add to the recreation and access potential of the area by allowing easier access to parts of the forest previously closed. They can open up areas for other purposes.

There are increased concerns expressed by conservation bodies and the general public to changes in their environment, (and building of forest roads is certainly that). This manual attempts to meet these concerns.

The Manual deals with specific aspects to be considered when planning, surveying and constructing forest roads in mountainous terrain.

Particular attention is drawn to the principles of general planning of opening up mountain forest resources with reference to integrated planning of road networks. The benefit of the use of Excavators as prime construction machines is explained and detailed.

Reference is also made to parameters which influence road costs and present a simple formula as well as some figures to help with costing based on a wide experience in road construction. A large proportion of the manual is dedicated to describing, in detail, an efficient road surveying method by means of simple surveying instruments. The method presented in this report is the so-called gradeline or "zero-line" method which is commonly used, especially in mountainous terrain in many countries of the world.

The Manual also deals specifically with the description of surveying instruments, road reconnaissance and routing techniques.

TABLE OF CONVERSIONS

1 metre (m)

- 3.280 feet or 1.093 yards

1 kilometre (km)

- 0.621 mile

1 cubic metre (m3)

- 35.314 cubic feet

1 hectare (ha)

- 2.471 acres

1 litre (1)

- 0.219 gallon (Imp.) or 1.759 pints

1 kilogram (kg)

- 2.204 pounds

1 kilowatt (kw)

- 1.341 fly wheel horse power (fw hp)

1 inch

- 2.540 cm

1 foot

- 0.3048 m

1 yard

- 0.9144 m

1 mile

- 1.609 km

1 square yard

- 0.83613 m2

1 square mile

- 2.59 km2

1 cubic foot

- 0.02832 m3

1 cubic yard

- 0.765 m3

1 gallon (Imp.)

- 4.546 litres

1 pound

- 0.4536 kg

Note: Values have been rounded

This electronic document has been scanned using optical character recognition (OCR) software and careful manual recorrection. Even if the quality of digitalisation is high, the FAO declines all responsibility for any discrepancies that may exist between the present document and its original printed version.


Table of Contents


2. GENERAL PLANNING OF OPENING UP MOUNTAIN FOREST RESOURCES

2.1 ROAD-NET PLANNING
2.2 AERIAL PHOTOGRAPHS AND MAPS
2.3 ROAD TYPES
2.4 ROAD STANDARDS

2.4.1 Access Roads
2.4.2 Main Forest Roads
2.4.3 Secondary Forest Roads (Feeder Roads)
2.4.4 Skid Roads (Skid Trails)

2.5 ROAD-NET DENSITY AND SPACING
2.6 INTEGRATED PLANNING OF ROAD NETS AND CABLE SYSTEMS
2.7 ROAD LOCATIONS IN HILL AND MOUNTAIN SIDE AREAS

3. PARAMETERS INFLUENCING THE ECONOMIC OF ROADS (BY HEINRICH)

3.1 CLIMATE
3.2 TERRAIN AND SOIL
3.3 STAND AND TREES

4.0 ENVIRONMENTAL ASPECTS - FITTING NEW ROADS INTO THE LANDSCAPE

4.1 INTRODUCTION
4.2 BASIC DESIGN PRINCIPLES
4.3 LANDSCAPE DESIGN
4.4 ROAD LOCATION
4.5 VERTICAL AND HORIZONTAL ALIGNMENT
4.6 THE ROADLINE SCAR
4.7 ROAD MATERIALS
4.8 CULVERTS
4.9 BRIDGES
4.10 CONCLUSIONS

5. ROAD COSTS ESTIMATES

5.1 GENERAL
5.2 STAKING, FELLING, FORMING, CLEARING AND MISCELLANEOUS WORK3
5.3 GRAVELLING

6. SURVEYING

6.1 GENERAL
6.2 SURVEYING INSTRUMENTS

6.2.1 Clinometers
6.2.2 Compasses
6.2.3 Tapes
6.2.4 Barometric Altimeters
6.2.5 Additional Equipment

6.3 ROAD RECONNAISSANCE

6.3.1 Planning Area
6.3.2 Maps And Aerial Photographs
6.3.3 Fieldwork And Cooperation
6.3.4 Work Procedure
6.3.5 Field Control

6.4 ROUTING TECHNIQUES

6.4.1 Introduction
6.4.2 Personnel (size of location crew)
6.4.3 Instruments and Equipment
6.4.4 General Rules for Road Location
6.4.5 Method of Location
6.4.6 Special Problems
6.4.7 Right of Way

6.5 FIELD NOTEBOOKS

7. MAPPING, CALCULATIONS AND DRAWINGS (BY SEDLAK)

7.1 GENERAL REMARKS
7.2 DIVIDER SETTING
7.3 PLOTTING THE ROAD LINE
7.4 CROSS SECTIONS AND DETERMINATION OF CUT VOLUMES

7.4.1 Cross Sections
7.4.2 Determination of Cut Volumes

8. PERFORMANCE

8.1 MECHANIZATION IN FOREST ROAD CONSTRUCTION
8.2 MAIN MACHINERY USED IN FOREST ROAD CONSTRUCTION

8.2.1 Tracked Tractors
8.2.2 TRAXCAVATORS
8.2.3 EXCAVATORS
8.2.4 Rock Drills
8.2.5 Graders
8.2.6 Loaders
8.2.7 Dump Trucks
8.2.8 Rollers/Compactors

8.3 CALCULATION OF MACHINE COSTS

8.3.1 Basic Data Used in the Calculations
8.3.2. Cost Calculation15 Cost per hour in US$

9. EXCAVATOR METHODS OF CONSTRUCTION

10 DESCRIPTION OF THE ENVIRONMENTALLY SOUND ROAD CONSTRUCTION TECHNIQUE IN STEEP TERRAIN

10.1 CLEARING OF THE CONSTRUCTION AREA
10.2 ROAD CONSTRUCTION BY EXCAVATOR
10.3 ROCK DISINTEGRATION

10.3.1 Hydraulic hammers
10.3.2 Rock blasting
10.3.3 Mass transport
10.3.4 Road drainage
10.3.5 Surfacing and shaping
10.3.6 Slope protection and stabilisation

10.4 DESCRIPTION OF THE ROAD CONSTRUCTION EQUIPMENT
10.5 ESTIMATING PRODUCTION AND PERFORMANCE RATES

10.5.1 Excavator
10.5.2 Rock blasting

10.6 ESTIMATING COSTS
10.7 QUALITATIVE ASSESSMENTS OF ENVIRONMENTAL IMPACTS

11. DRAINAGE SYSTEMS AND PROTECTION WORKS FOR FOREST ROADS

11.1 DRAINAGE SYSTEMS

11.1.1 Open Top Culverts
11.1.2 Sub-base Culverts

11.2 CULVERT LOCATION
11.3 CORRUGATED STEEL CULVERTS:
11.4 INSTALLATION
11.5 MAINTENANCE

12 PROTECTION WORKS FOR FOREST ROADS

12.1 SLOPE PROTECTION AND STABILIZATION
12.2 SLOPE DRAINAGE
12.3 REVEGETATION OF ROAD EMBANKMENTS AND SLOPES
12.4 STABILIZATION OF DRAINAGE-WAYS
12.5 SLOPE PROTECTION WITH ENGINEERING STRUCTURES
12.6 PROTECTION OF ROAD EMBANKMENTS AGAINST TORRENTIAL WATERFLOWS

13 MAINTENANCE OF FOREST ROADS

14 CONTRACTS

14.1 CONTRACT CHECKLIST
14.2 SPECIMEN CONTRACT

REFERENCES