1 Department of Forestry, Ministry of Agriculture, Norway.
This paper discusses the historical development and trends of forest road construction such as we see them in Norway. It is refers to the methods and equipment used under varying conditions with regard to geology and topography. It also discusses what environmental issues are particularly significant in road planning and construction, and by what means the authorities may influence the choice of construction methods.
Modern forestry depends on a sufficient road system, and the construction of forest roads creates considerable and irreversible encroachment to the terrain and nature. Accessibility and conditions for use of the areas served by the road change drastically, creating conflicts between forestry and the public in Norway. The conflict of interest increases, depending on the distance to the urbanized areas, the previous virgin appearance of the area being developed and the existence of special nature and environmental qualities.
The productive forest area in Norway is about 7 million ha. Presently, about 45 000 km of private forest truck roads are built on this area. In addition, it has been estimated that public roads and other private roads of significance to the transport of timber and logs amount to about 20 000 km. In total, this indicates an average road density of 9.2 m/ha, but large regional and local variations exists within this figure, from 20-25 m/ha in some of the most productive and intensively operated areas, to 2-5 m/ha in the low productive, mountainous areas.
Yearly road construction by forest trucks has been for many years between 800 and 1 200 km, with a declining tendency in the last few years. In 1995, only 400 km of new truck roads were built. We consider this as a natural development, while the future reconstruction level should remain at about 800 km a year.
Forest roads are constructed to fulfil the transport needs of forest trade and are financed by this trade. The adjustments to be made due to environmental considerations must not be so comprehensive that the roads fail to meet their daily forestry transport functions. This means that the roads must fulfil certain technical specifications and remain within acceptable economic cost frames. Under these assumptions, the most relevant environmental elements to be considered when constructing forest roads are:
· lakes and running waters;
· bogs and swampy areas;
· landscape border zones;
· multiple-use interests;
· cultural heritage;
· aesthetic aspects.
With these elements in mind, the general instructions for forest road construction in Norway may be summarized in the following points:
· The road location must be adjusted to the terrain formations. This means that we should minimize straight alignments, with the curvatures following the existing terrain formations both in the horizontal and vertical alignment. The average road haul on secondary roads is only 2-5 km, which means that the speed has little relevance to total transport costs. Such road designs create better contact with, and accessibility to, the terrain to be served.
· If the road construction material within the road location is of low quality, it is preferable to open up a large gravel pit rather than trying to obtain material from several small borrow pits along the road. Roadbeds built with hauled-in good-quality material placed on top of the ground level often create minimum visual disturbance and make a technically good-quality road.
· Much emphasis should be placed on the aesthetic aspects of the road. All waste material should be removed or buried, and terrain encroachment must be minimized.
· It is of vital importance to prevent any obstruction to running water to avoid pollution or erosion problems.
In addition, special considerations must be taken with regard to biodiversity, cultural heritage, outdoor life and important nature elements where these exist.
Most forest road contractors receive their income from the construction of several small individual road projects. The employers are usually small forest owners who build the road jointly. The contractors have adjusted to this market situation and have access to various types of road building machinery. Each individual on the construction crew is skilled and has a comprehensive experience in operating the various pieces of machinery.
Any contractor involved in future new construction or reconstruction of forest roads must develop sufficient knowledge and skill of environmentally friendly construction methods. This is a qualification requirement just as important as the technical/economic aspects related to forest roads, and the competition for the jobs will eventually force out of the market the contractors that are unable to manage this part of the work.
Construction of new forest roads is often criticized from an environmental point of view, in Norway as in other parts of the world. The main issue of discussion is often whether roads should be built or not, but this paper will discuss construction methods and equipment to be used under the assumption that all terms and conditions for road construction have been met. The challenge for the road planning officer and the road contractor is to take into account all environmental aspects when choosing methods and equipment for the different jobs.
This paper discusses the historical development and trends such as we can see them in Norway. It is refers to the methods and equipment used in Norway under varying conditions with regard to geology and topography. It also discusses what environmental issues are of particular significance in road planning and construction, and by what means the authorities may influence the choice of construction methods.
1. The forest evolution
The utilization of the natural resources has been a fundamental condition for settlements and development throughout the entire Norwegian history. The country is characterized by low population density and scattered settlements. Even with relatively large areas available to each inhabitant in Norway, much of our non-cultivated areas and outfields have been influenced by human activities.
From ancient times the mountains and the forested areas were used for summer farming and grazing, and materials for housing, tools and firewood were collected from most forested areas.
In the eighteenth and nineteenth centuries, society gradually changed from a strict agrarian settlement system to industrialized communities. The alteration had severe consequences on the forest. Mining, shipping and trade of timber and sawn lumber resulted in a severe overexploitation of the forest resources, creating large completely deforested areas towards the later part of the nineteenth century. This situation made it necessary to establish a new national forest policy, and throughout the entire twentieth century the overall objective of the management of the Norwegian forests has been to re-establish the forest resources on a sustainable use concept. The outcome of this policy change is that the standing volume and the increment have tripled during a hundred-year period. Today we have more forest resources than ever before in modern times. The historical background is the reason why we hardly have any old-growth or virgin forests in Norway. However, construction facilities and other remains from early human activities may still be found, some of them in most inaccessible areas, and these remains represent environmental qualities that we today wish to protect for the future.
2. Status of the forest roads in Norway
The productive forest area in Norway is about 7 million ha. Presently, about 45 000 km of private forest truck roads are built on this area. In addition, it has been estimated that public roads and other private roads of significance to the transport of timber and logs amount to about 20 000 km. Total, this indicates an average road density of 9.2 m/ha, but large regional and local variations exist within this figure, from 20-25 m/ha in some of the most productive and intensively operated areas, to 2-5 m/ha in the low productive, mountainous areas. As road construction must always be based on technical and economic evaluations, such density variation must be expected. Today, we consider the main road system to be adequately developed in many areas, but extensions and secondary roads still remain to be built. Many of the main roads were constructed 40-50 years ago when the demands for technical standards, construction methods and transport equipment were of a completely different standard than today. The need for reconstruction of the older roads is substantial, especially for relocation of gradients and curvature and reinforcement of axle load capacity. This reconstruction work creates great challenges from an environmental point of view.
Yearly construction by forest trucks has been for many years between 800 and 1 200 km, with a declining tendency during the last few years. In 1995, only 400 km of new truck roads were built. We consider this as a natural development, while the future reconstruction level should remain about 800 km per year.
3. Conflict of interests between environment and forestry
Modern forestry depends on a sufficient road system. The construction of forest roads creates considerable and irreversible encroachment on the terrain and nature. In Norway accessibility and conditions for use of the areas served by the roads change drastically, creating conflicts between forestry and the public. The conflict of interests increases depending on the distance to the urbanized areas, the previous virgin appearance of the area being developed, and the existence of special nature and environmental qualities.
In many areas road construction is undesirable in the view of the environmentalists or the nature conservation people. The discussion, therefore, in many instances is related to if and where the road should be built, rather than how the road should be built. It is, however, essential that the projects, once it is decided that they should be implemented, are built according to environmentally, technically and ethically acceptable principles. The people responsible for the planning and construction of forest roads must pay attention to not harming any environmental qualities and assure that the roads are the best possibly adapted to the environment and terrain involved.
Forest roads are constructed to fulfil the transport needs of forest trade and are financed by this trade. The adjustments to be made due to environmental considerations must not be so comprehensive that the roads fail to meet their daily forestry transport functions. This means that the roads must fulfil certain technical specifications and remain within acceptable economic cost frames. We occasionally experience requests to locate the forest roads where they have no value for forestry transport or operation, or to build the road in such a way that it will not support the loaded trucks, or environmental demands that are too costly to make the project economic feasible. These are demands and accommodations that may not be combined with the main purpose of the road, and cannot be accepted by forestry.
Environmental issues relevant to forest road construction
Conditional requirements for paying adequate attention to the environmental aspects, is that the people involved have sufficient relevant knowledge and realize what encroachment and disturbances are tolerable without destroying the environmental elements to be protected.
Much effort has been taken to inform and increase the area of knowledge among contractors, forest owners, and officials on forest road construction in relation to biodiversity aspects, multiple use concepts and cultural heritage. In addition to increasing the knowledge, it is most important to work towards establishing attitudes that environmental concerns are as important as technical standards when constructing forest roads. This educational process is still in progress. It is our intent to promote ecology and environmental subjects along with the economic and technical subjects in the future education of foresters and forest engineers.
1. Relevant environmental factors
As mentioned, some environmental motives or concerns may be difficult to combine fully with forest road construction in some instances. In this category are biodiversity, vulnerable biotopes and other factors that directly or indirectly may be destroyed or adversely influenced by road construction. The human activity, road construction and forest operation, has detrimental effects on the environment of these factors, and special areas of high biodiversity value may be best protected by relocating the road. If the road must be built through such an area, restrictions may be put on the use of the road such as avoiding vulnerable periods of the year. Such areas, however, must be identified and classified in the planning stage and is not discussed in this paper.
1.1 Lakes and running water
Protection of lakes and running water is the most important environmental factor to consider during forest road construction. It is essential that the activity avoids creating any pollution to running water, and that directional changes to rivers, creeks and waterways are not made. When crossing running water containing fish, the installation must not interfere with fish movements. There are examples of inadequate dimensioning of culverts that create landslides and severe erosion in steep terrain. This is not acceptable.
1.2 Bogs and swampy areas
This is another «Be Careful Area». Up to about 1970, large areas of bogs and wet forest land of high nutritional value were drained to increase forest production. This practice has resulted in that such areas are rather rare, and today the remaining areas must be left intact, if possible. Forest roads should, therefore, avoid such areas, if possible.
1.3 Landscape border zones
Landscape border zones are an example of other vulnerable areas. Landscape border zones are the belts adjacent to water, running water and wetland, including the transition zones between various vegetative covers, between steep and flat terrain, against cultivated fields and areas adjacent to certain elements of biological or geological nature. These zones are essential for fauna and flora and should remain intact if possible. The landscape retains its versatility and the visual impact of the forest roads is much less when these zones are avoided.
1.4 Multiple-use interests
Recreational use and tourism are important elements in Norway, and large areas of our outfields are heavily used by the local people and tourists for recreational use, outdoor activities and sport. In the heavily used areas much emphasis is placed on adapting the roads to trails, cross country tracks and other elements of importance to the public.
1.5 Cultural heritage
As mentioned in the introductory comments, there are enormous amounts of cultural heritage from earlier human activities within the Norwegian forests. Statutes automatically protect some of these, while others must be evaluated individually on their own merits. It is highly recommended to adjust the roads keeping most of these remains registered and untouched. The knowledge of the extent and existence is still relatively limited, and efforts are being made to educate and train road planners and contractors to be able to detect, recognize and register various elements related to cultural heritage in their daily work.
1.6 Aesthetic aspects
In consideration of public acceptance and opinion, the aesthetic values must be emphasized. Clean-up and other after-construction work to improve the visual appearance are now considered as normal part of the road construction cost. Attempts are constantly made to adjust the construction methods in such a way that the aesthetic aspects are considered on an equal level with the technical specifications. Landscape considerations are mainly taken during the planning and location stage, but also through methodical selection of the construction method to be applied.
Development of construction method and equipment
Forest road construction utilizing modern machinery was initiated in Norway in the early 1930s, but did not take off until after the second world war. In the 50-year period since that time, an enormous technological advance has taken place in the forest operations aspect, terrain and long haul road transport. The improvement of the road system has been an important part of this development, and the technical, geometric and environmental aspects have changed in line with the rest of the premises.
In this paper this development has been divided in three periods:
· The Pioneer Period
· The Development Period
· The Multiple-Use Period
1. The pioneer period
The initial objective of road building was to gain access to the forest areas replacing the timber floating rivers as the long arterial transport system. The machines used were small dozers and the roads were lightly built using material available adjacent to the road location. Rock blasting was avoided, if possible, due to the high costs involved. The roadbed was seldom built on fills, and the road was placed low in the terrain. Waste material and large rocks were placed along the roadside and the drainage system was inadequate or not present. The result was light, excessively curved roads with low axle load capacity. However, as the transport equipment consisted of small trucks without trailers, and the terrain transport was effected during winter times on frozen ground, the roads were adequate for their times and use.
2. The development period
The main development period in Norwegian forestry was from 1960 up to the early 1980s, and more than 50 percent of the total forest road system was developed during that time. This period was the prime period for the state-of-the-art for the logging engineer designing and building roads which were required to have straight alignments and designed curvatures. Functionality and technical standards were the dominating premises during the planning and construction stage, and consideration of landscape adaptation, multiple use and environment were not major issues. Heavy equipment was introduced in road construction, and the roads were built on large fills and heavy cuts both in moraine materials and rock. The dozers were still an important part of the road building machinery, but gradually the shovels or the excavators replaced the dozers in the clearing and grubbing as well as the levelling stages, partly due to the fact that the roads gradually were entering more difficult terrain. The relation between manual costs and machinery changed with preference towards the use of machinery, and the contractors invested in several types of large machinery, excavators, rock drills, wheel loaders, dumpers, and trucks. Favourable tax adjustments and depreciation regulations stimulated this development.
The logging methods changed accordingly with the introduction of harvesters and forwarders. The use of this machinery involves year-round occupation and the industry requires an even flow of wood supply. The roads had to be reinforced to support heavy machinery in the summer season as well. The size of the transport equipment increased both in length, width and load bearing capacity, thereby changing the demands for improved road alignment and axle load capacity.
3. The multiple-use period
The public reaction against forest road construction started in the early 1980s. Environmental demands were raised and the forestry trade wanted a more differentiated road system due to the costs involved. New, more flexible road construction methods were introduced enabling a more suitable solution adapting the situations to the various existing conditions. Knowledge of environmental aspects, forestry and technology are still increasing resulting in improved adjustment of the road location and construction procedures.
The general instructions for forest road construction in Norway may be summarized as follows:
· The road location must be adjusted to the terrain formations. This means that we should minimize straight alignments, with the curvatures following the existing terrain formations both in the horizontal and vertical alignment. The average road haul on the secondary roads is only 2-5 km, which means that the speed has little relevance to total transport costs. Such road designs create better contact with, and accessibility to, the terrain to be served.
· If the road construction material within the road location is of low quality, it is preferable to open up a large gravel pit rather than trying to obtain material from several small borrow pits along the road. Roadbeds built from hauled-in good-quality material placed on the top of the ground level often create minimum visual disturbance and make a technically good-quality road.
· Much emphasis should be placed on the aesthetic aspects of the road. All waste material should be removed or buried, and terrain encroachment must be minimized.
· It is of vital importance to prevent any obstruction to running water to avoid pollution or erosion problems.
In addition, special considerations must be given to biodiversity, cultural heritage, outdoor life and important nature elements where these exist.
Methods under varying conditions
There are great variations in Norway with respect to topography and geology. Construction methods and, consequently, environmental considerations must vary according the prevailing conditions of the ground where the roads are to be built. In spite of these variations certain techniques or construction methods and type of machinery are common among most of the contractors.
1. Machinery available
Most of the forest roads are built by contractors that have specialized in this work and have gained knowledge of regulations and standards. Usually the forest road contractor companies are small, 2-5 employees, but have access to substantial machinery. The most common machines available to a forest road contractor company are:
· Track mounted shovels (excavators), 15-25 tons. Usually more than one unit.
· Wheeled front-end bucket loader, 12-18 tons.
· Gravel truck or dumper, usually both types (10-12 m3 load capacity).
· Rock drilling equipment, usually pneumatic or hydraulic.
· Compacting equipment (vibrating roller).
In addition, many contractors in addition have access to a dozer and/or a road grader, a gravel sorting device and a rock crusher. Some contractors specialize in rock blasting and production of crushed rock for ballast and surfacing material and offer their services to other contractors. The machines are, in general, fairly new and in good condition.
2. General methodology
Except for the main access roads with heavy traffic, the forest roads in Norway are constructed with relative low standards. The traffic intensity is relatively low with yearly volumes transported varying between a few hundred cubic metres up to 50 000 m3. In order to lower the cost, we try to use local material, even if this material may vary in quality. It is, therefore, important to sort out the material and make optimum use of the material available. Shovels or excavators are best suited for this work. Very often loose material is scarce and a shovel may utilize the material much better than a dozer. As a general trend, therefore, the use of shovels has been the dominating method during the last 20 years. There are still contractors using a dozer as their main piece of machinery and produce high quality roads under difficult conditions. The ideal situation is the combination of shovel and dozer working and levelling out the material.
A typical working procedure for constructing a forest road (1-3 km under various terrain formations) is described in the following. The contractor team consists of 2-3 people. On larger projects, two shovels would be preferable in addition to the machinery previously described.
1. A large shovel, 18-25 tons removes the vegetation cover, stumps and top soil and places this material in rows along the toe of the planned fill section.
2. Simultaneously with the removal of the vegetation cover, rock and large boulders to be blasted are uncovered, and the initial preparation for the subgrade levelling is made where proper loose material is available. Any sections with good road material are cleared from topsoil. Culvert locations are prepared for installation.
3. The second crew member starts rock drilling and blasting. Usually track-mounted rock drills are used, but on smaller road projects or projects with less rock, manually operated hand drills powered from tractor mounted air compressors may be used. It is important to drill and blast the ditch line simultaneously with the roadbed in order to utilize this material.
4. In the next step the shovel goes back and works on the rock blasted sections. Even if efforts have been made during the design stage to balance the excavation material over short segments, there is usually a need to spread out the excavated material along the road location. The alternative is to design the road in heavy cuts and fills, which is considered undesirable today. The surplus material of blasted rock and moraine material must, therefore, be loaded on a truck and end-hauled to segments short of material. Culverts are placed during this stage.
5. Usually the complete grubbing and levelling work of the subgrade is done by the shovel. However, the use of a dozer or a grader for levelling this material is to be preferred. This work may be combined by compacting the material using a vibrating roller or a grid-roller pulled by the dozer or the grader.
6. The next step is to apply additional subgrade material or ballast, if needed. Occasionally the rock blasting and the subgrade work is done during winter time, while the final levelling, reinforcement and finishing work is prolonged to the following fall season.
7. Finally the shovel passes over the road grade once more, smoothes cuts and fills, levelling and cleaning up borrow pits, gravel and rock pits and replacing humus and top soil on the fill slopes.
At this stage the road is ready for adding the wearing course or the surfacing material. But it may in some instances be preferable to delay this operation until the subgrade is stabilised and possible damages are corrected (1-2 years).
3. Rock blasting
Several years ago, rock blasting on a forest road construction project was expensive. Even today this work may involve excessive cost, but up-to-date equipment and revised techniques have resulted in a considerable decrease of rock drilling and blasting costs.
In Norway most forest road construction projects involve rock blasting which may involve great environmental challenges:
· From an aesthetic point of view, solid rock cuts and fills are problematic since they result in heavy dominating encroachments on the terrain.
· By using improper equipment and blasting techniques, the area adjacent to the road location may be damaged or appear contaminated.
3.1 Recommended blasting techniques
If solid rock cuts are unavoidable, an effort should be made during the planning and location stage to minimize the encroachment and adapt in the best possible way to the terrain formation. Much emphasis must be placed on utilizing the blasted rock in the roadbed to avoid waste of valuable material, and create problems to the local environment.
Therefore, solid rock must be drilled and blasted such that usable-size material is created. The size of the blasted rock may depend on height of fills and terrain formation. On steep hillsides it may be preferable to utilize some larger rocks (up to 1 m3) in toes of fills or as other support. Large rocks may also be used as plastering fills to prevent erosion into creeks and rivers.
In general however, it is preferable to blast the solid rock into as small sizes as possible, but in this respect there is a certain conflict of interests between modern, effective techniques and costs involved in creating the small fraction material. The reason behind the decreased blasting expenses during the last years is the introduction of larger track-mounted rock drilling equipment replacing the manual operated drill. By using large-diameter drill bits, there may be a larger distance between the holes. However, if this distance becomes too far, undesirable size material is created. This may be compensated by drilling below the subgrade level and utilize correct blasting material, creating fine graded material in the lower section and larger blocks at the top level of the blasted material. Large shovels may then be used to replace these layers so that the large material is placed on the bottom layer and the fine material on the top layer.
3.2 Ditch blasting
The same procedure may be used when the drainage system must be blasted. All the blasted material is then removed from the ditch line, the fine material is used in the roadbed and the coarse material is relocated into the ditch keeping the depth to the required minimum. The water may pass around the larger rocks without creating erosion. Excessive depth of the ditch line causes unnecessary visual impacts and creates functional problems preventing accessibility from the road to the adjacent area.
The method of filling large blocks back into a deep blasted ditch line serves multiple purposes:
· excellent drainage;
· improved contact between the road and the terrain;
· less dominating road appearance.
One method that should be mentioned regarding rockwork is the use of rock splitting hammers. A hydraulic or pneumatic operated hammer is mounted in the place of the bucket on the shovel arm. All model shovels may be used, but larger work requires machines of 20 t or more.
Rock splitting hammers are being increasingly used, especially in improvement work on older roads. The applicability depends on the physical characteristics of the rock. The method is best suited for harder, brittle rock, which makes the use of this equipment economically and technically competitive in respect to other methods.
4. Areas with loose rocks and boulders
In some regions in Norway, areas of large loose rocks and boulders cause severe forest road construction problems. One alternative is to drill and blast the rocks or use rock splitting hammers, but this is expensive. When dozers are used, the boulders are pushed and placed along the roadside and create barriers against traffic to the adjacent areas. It is a great operational disadvantage and creates undesirable visual impacts.
By using large shovels, most of the boulders may be dug below the subgrade level. The advantage is twofold, hiding and reinforcing the roadbed. One disadvantage is that it may create a rather dominating road due to the excessive amount of material to be handled, but this disadvantage is considered smaller than the advantage of getting rid of larger rocks.
5. Areas of low load-bearing capacity
In the last years it has become more and more common to place fibre cloth or geonet on low bearing ground (boggy, marshy land and ground with fine coursed material), laying on it pit run moraine material or rock from external gravel or rock pits on top. The fibre cloth is continuously rolled out directly on the top of the untouched ground. 40-80 cm of moraine material or fine graded blasted rock is placed on the cloth, depending on the quality and load supporting ability of the ground.
If the humus layer in the marshy areas is untouched, the load-bearing capacity of the ground becomes substantial in a foreseeable future after the road is built. Formerly, branches and small, low quality wood were used as reinforcement material. The ground moisture kept the wood material intact for many years, often fifty years and more.
The roads built by this method present a good running surface, are easy to maintain, create only minimal visual impact and are environmentally sound as the water drainage system and the terrain are only slightly disturbed. The alternative is comprehensive drainage of the area combined with replacement of material or a substantial fill section using the existing low-quality material. Ground disturbance of these areas is destabilizing and the material is not suited for road construction.
Even on flat land areas with little soil cover, the alternative of placing hauled-in material on the top of the untouched ground may be a better solution than rock drilling in shallow holes over long distances. If the transport distance from an acceptable pit is not too far, this method is also economically preferable. As such blasting easily creates visual impacts and damages to the adjacent road location, the method is also environmentally preferable.
6. Steep terrain
The use of dozers on steep side hills usually creates excessive amounts of side cast or waste material, as most of the roadbed must be built on solid ground. In addition, it is difficult to build the cut-slopes stable and gentle enough to prevent future slippage and slide. Construction work on this terrain is critical for aesthetic reasons and erosion problems and, under these conditions, large shovels are of great advantage, as part of the roadbed may be constructed partly on fill and compacted in layers up to the final road width.
The working procedures are as follows: The shovel starts at the toe of the final fill-slope and constructs a "catching ditch line" for the footing of the road. The machine then continues working with the material, placing the larger rocks in the catching ditch line as a support wall for the road fill. Smaller rocks and proper fill material may then be placed on the top of the support wall and compacted. When the foundation is completed, the shovel moves to the top of the cut-slope and constructs a slope at the proper angle for the local material. The bucket is used for compacting and levelling and placing rocks that were needed to stabilize the toe of the cut-slopes (especially on fine coursed material). Large fills (above 1 m) must be compacted by the large shovel used in the construction, or by vibrating rollers if smaller shovels are used.
7. Conditions regarding lakes and running water
One of the most important environmental concerns in forest road construction is how to handle the problems related to water drainage, creeks, rivers and lakes.
It is considered increasingly more important to avoid disturbing the natural waterways during road construction. This includes surface water as well as ground water movements. When a road cuts the hillside, most likely the natural waterways are disturbed. Where it is of particular interest to avoid this, the road should be placed on fills by hauled-in material if possible. Usually, however, the roads are built in balanced cuts and fills with the centre line close to the ground level. The water is collected by the ditch line and directed under the roadbed through culverts at various distances. It is most important that the culverts be placed close enough and be sufficiently dimensioned to handle floodwater runoff. Water may cause severe damage from an economic and environmental point of view, and we consider the project plan as an important tool in this respect.
As a rule, fill material should never be placed in or within the reach of streams or lakes and we aim at locating the road at an adequate distance from the water for environmental and technical reasons. If the road must be placed along shorelines or streams, the road material must be protected against erosion by plastering with large rocks. Equal considerations must be made at bridge crossings and larger culvert installations.
8. Reconstruction of older roads
Reconstruction of older roads is a special problem when alignment, gradients and axle load bearing capacity are inadequate. In many cases, these roads have developed over the years into idyllic recreational roads heavily used for outdoor activities by the public. Reconstruction work in these areas may be as controversial as new construction, and requires great concern during the planning and construction stages. It may be difficult to utilize excessive material and waste as for new constructions. By no means should this material be placed along the roadside. It must be transported to areas where it may be deposited, buried or levelled out. Therefore, reconstruction work is considered today non-feasible without use of an adequate shovel.
It is our experience that the clearing width must be described and marked in detail on reconstruction projects through existing forest stands as the working room for the machinery is often underestimated. A too narrow clearing zone also creates damage to standing trees. This means that a minimum of 5 m on each side of the roadway must be cleared. This usually gives space for levelling the waste material, thus eliminating loading and transport costs.
1. The effect of the authorities on choice and development
Since 1991, forest road construction is regulated through national forest road construction specifications pursuant to the Forestry Act. Road plans must be evaluated in relation to forestry benefits, landscape adaptation and environmental aspects. The environmental authorities and relevant organizations have the right to make comments on all forest road plans, and may appeal to the County Governor against any decision made by the local community authorities. The final decision or approval of a road plan may include conditional requirements regarding location, reduction of road distance, construction method, use of road material, landscape adaptation, clean-up and regulation of future use. If conditional requirements are not specified, the general regulations and specifications still remain for environmental aspects and finishing work.
The authorities have not established any regulations regarding the type of equipment and machinery to be used. However, strict requirements are set to the final product, thereby setting the precedence for environmentally friendly construction methods. These requirements are set with regard to individual road construction projects, but also through standards and regulations. The Norwegian authorities do not wish to specify methodology regulations as this may restrain the natural development of environmentally friendly and efficient methods through the free choice of the contractors within the quality demands put on the final product. It is customary to place the road projects on bids so that the contractors compete for the best price and quality.
With regard to the regulations and measures established by the authorities to direct and guide the planning and construction of forest roads, reference should be made to the basic paper presented by Mr. Bjørn Akre.
2. Trends and final conclusions
The forest road contractors receive their income from constructing several small individual road projects. The technical planning basis usually is relatively simple, and a complete road plan including material quantity calculations and detailed plan and profile sections may only be available on the larger projects. The employers are usually small forest owners who build the road jointly. The contractors have adjusted to this market situation and have access to various types of road-building machinery. Each individual on the construction crew is skilled and has a comprehensive experience in operating the various pieces of machinery. Typically, the individual contractor operates within a local market, where he knows the employers and the geographical and geological conditions.
Besides, there is a trend to hire specialists as subcontractors for certain work, such as larger rock blasting work, rock crushing and transport. Some contractors specialize in reconstruction and maintenance of older forest roads, which will be increasingly more important in the coming years.
Any contractor involved in future new construction or reconstruction of forest roads must develop sufficient knowledge and skill on environmentally friendly construction methods. This is a qualification requirement just as important as the technical/economic aspects related to forest roads, and the competition for the jobs will eventually force out of the market the contractors that are unable to manage this part of the work.
In my opinion, in Norway we have gained valuable experience on these aspects of forest road construction and hope that these experiences, as outlined in this paper, may be of some value in other parts of Europe.