FOREST ROADS IN ROMANIA - PLANNING AND DESIGN
FOREST ROAD PLANNING AND LANDSCAPING
OPENING-UP PLANNING TAKING INTO ACCOUNT ENVIRONMENTAL AND SOCIAL INTEGRITY
ASPECTS REGARDING THE ACCESSIBILITY OF MOUNTAINOUS STANDS SUBJECT TO WINDFALLS
THE MULTIPLE USE OF FOREST ROADS AND THEIR CLASSIFICATION
ENVIRONMENTALLY SOUND FOREST ROAD CONSTRUCTION IN NORDRHEIN-WESTFALEN (NRW), GERMANY
TECHNOLOGICAL REQUIREMENTS FOR THE LOCATION OF FOREST ROADS IN SLOVAK CONDITIONS
ASSESSMENT OF FOREST ROAD ALTERNATIVES WITH SPECIAL EMPHASIS ON ENVIRONMENTAL PROTECTION
FUZZY EXPERT SYSTEM LAYING OUT FOREST ROADS BASED ON THE RISK ASSESSMENT
O. Cretu1 and C. Rusnac2
1 National Institute of Wood. Romania.
2 ROMSILVA R. A., Bucharest, Romania.
Abstract
The Romanian forest lands extend over 6.3 million ha, representing 27 percent of the total area of the country. The distribution of forest lands is such that 90 percent of it is on landscapes classified as hills or mountains. Hence it follows that the majority of forestry works are carried out on rough topography where the slopes are frequently more than 25 percent.
Forest accessibility is low because of a lack of adequate access roads. From the total of 6.3 million ha of forest land, only 4.1 million ha could be considered accessible; the rest of these forest lands are not connected to an existing transport system. The density index of the forest road network is 6.2 m/ha. At present the forest lands are served with a 39 186 km transport system (truck roads, narrow gauge railways, public roads, servicing roads) intended to cover various forest activities.
According to detailed studies, which have considered the economic and environmental conditions and consequences, the optimum transportation system density averages about 13.3 m/ha. This density results in average collecting distances of 700-800 m. Approximately 42 260 km of roads will have to be built to achieve this system density.
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The national forest road system has a total length of 39186 km made up of:
|
· forest truck roads |
29 743 km |
|
· forest railways |
365 km |
|
· public roads |
7 625 km |
|
· roadways intended for other sectors |
1453 km |
This road network was mainly designed by the Research and Design Institute for Wood Industry in the present National Institute of Wood during 45 years which is the only specialized institute in Romania.
The major part of forest roads was built between 1960 and 1985. After 1985 forest road construction was reduced continuously.
Of the total forest land of 6.3 million ha, no access by transport road exists for 2.2 million ha. To provide access to this area is a priority in the forest policy of the Forest Department of the Ministry of Waters, Forest and Environment Protection and ROMSILVA.
The design and construction of forest roads should comply with the Department's standards set on the basis of the Road Taw.
According to these regulations, forest roads are classified, depending on their importance and function, as:
· First category roads - high service tracks provided for groups of production units, used for the transport of over 50 000 t/a.· Second category roads - main medium-service tracks provided for production units, used for the transport of between 50 000 t/a and 5 000 t/a.
· Third category roads - secondary low-service tracks established in small forest areas within production units, used for the transport of up to 5 000 t/a.
Table 1. Geometric specification, dimension characteristics and construction types of forest roads
|
Road category |
Road type |
Intended forest area |
Annual traffic |
Max. speed at min. curve radius |
Min. radius of curve |
Width |
Max. slope |
||
|
Platform |
Truck road |
Loaded |
Unloaded |
||||||
|
I |
High service track |
Over 10000 |
Over 50000 |
50-25 |
7-8 |
7.0 |
5.5 |
85-10 |
8-10 |
|
II |
main |
1000-1000 |
50000 -5000 |
40-20 |
7-9 |
5.0 |
4.0 |
50-15 |
9-11 |
|
III |
secondary |
under 1000 |
under 5000 |
20-10 |
9 |
3.5 |
2.75 |
15-10 |
11-12 |
Forest roads are of different types depending on their geometric and construction characteristics the forest area they are intended to serve, the amount of wood to be extracted, the logging period, average annual traffic, and the maximum speed at minimum curve radii.
Forest roads should be designed and constructed considering the following points:
· location of wood, volume, and assortments to be annually transported, as well as management purposes;· natural conditions of relief, soil structure and geophysical characteristics of the land;
· economic conditions and costs required for road construction, maintenance and operation;
· possibilities of mechanized operations;
· execution period.
When planning roads, it must be kept in mind that agricultural fields and areas needing expropriations cannot be used. On hilly and mountainous regions, where wood is spread on slopes, the types of forest depend on the topography, e.g. valleys, hills and high terrain.
The platform is the main part of a road; its width is the first criterion for the classification of forest roads that are formed the track and verges. High-service roads have two lanes, while main and secondary roads have one lane. In the one-lane roads, cross-stations of 5.5-6 m width and 20 m length are located at 400 m interval. Surface waters are collected and drained through ditches, drains, and small trenches.
Protection and consolidation works for embankments are carried out by retaining walls, natural stone revetment walls, gabions, groins, and enrockments using mainly local materials, stones and broken rocks.
River crossings are by bridges and culverts. The main culvert types are tube and slab culverts. The main culvert type is established on the basis of hydraulic estimation approved by the specialized authority - the Office for Water Management.
To establish a road system the following points are considered
· road type
· annual average traffic
· strength and type of slopes
· investment estimate
Local materials are mainly used for the forest road superstructure. A superstructure system is used for roads with heavy traffic.
Currently, the National Institute of Wood carries out forest road design. With its branches located throughout the forest lands, highly skilled specialists can ensure a unitary view of forest road design using the most convenient solutions that comply with the provisions of forest management.
In order to design roads, route reconnaissance and location, tachometry and surveying measurements are executed. The axis of the future road is located in the field through witness points located at a distance of 10-30 m distance, depending on the soil configuration. The data collected with conventional topographical apparatus or total stations (SOKKIA), used depending on the road type, are computer processed and transposed on the drawings.
The documentation prepared according to the approved regulations constitutes the basis for the following steps:
· Feasibility study concerning the location, economic analysis for funds.
· Technical project for the invitation to tender for the execution of the project.
· Details of project execution.
The execution technologies establish that forest roads must be built according to the topography of the forest lands using as much as possible mechanized means which offer environmentally sound standards.
Before the beginning of proper works for road construction, the ground must be prepared by clearing the land, extraction of root stumps, and removal of wood materials. Also, marshy zones must be drained.
In fields and low hilly areas, 90-95 percent of earthworks are made by mechanized means, while the figure drops to 75-85 percent on hills and mountains. The equipment used up to 3 m height is bulldozers that can perform step digging on 4:1 slopes, while on 6 m slopes, a 0.4-0.7 cm type excavator (digger) is used.
Manual work is employed to correct the slope surface up to the desired declivity, as well as to dig the ground at heights more than 6 m.
Rock breaking is effected for 95 percent by mine hole drilling with pneumatic hammers. Where the rock is covered with a ground layer, this is removed by manual digging. Access to the working places is gained by rock breaking, drilled manually, which constitutes about 5 percent of the total volume of rock breaking.
The detonation of explosive matters in the holes prepared in advance is for the protection of the trees in the adjacent zones, since it avoids the throwing around of rocks. For the explosion, the pyrotechnical method is used, which avoids the risk of accidents that may occur during atmospheric discharges if an electric detonation is used. The broken rocks are removed by bulldozers or excavators.
The material resulting from diggings and rock breaking is transported to deposits by means of bulldozers up to 50 m distance, truck and trailers for distances of over 50 m and tipping lorries for
The material resulting from diggings and rock breaking is transported to deposits by means of bulldozers up to 50 m distance, truck and trailers for distances of over 50 m and tipping lorries for distances more than 1 km. The material is loaded onto the vehicles by excavators. To protect the environment (avoiding tree damage caused by rolling rocks, water streams disturbances), the deposit must be located on areas with low cross slope, free from high floods.
To compact the earthworks on plain areas a -12 ton road roller is used; in narrow areas, a mechanical rammer.
Runoff collecting and draining is done by way of triangular ditches for depths of up to 40 cm. A trapezoidal shape is employed for deeper ditches.
The triangular ditches are made by a motor grader; the trapezoidal ones partially by a motor grader and then are finished manually. Ditches on rocks are made by mechanically drilled short holes, exploded pyrotechnically and then finished by pneumatic hammer.
The waters collected from ditches are led out of the road prism through culverts.
The retaining and stone revetment walls are built with big stones of cement mortar in mountainous areas, with river stones on hills and with concrete on fields. The necessary amount of concrete and cement mortar is prepared in appropriate working units and is then transported by road. In the case of small quantities, they are prepared on the spot.
On mountainous terrain, the enrockments are made of rock blocks laid by a 9-ton motor crane. Where rock blocks are not available, the enrockments are made of 1-cm concrete blocks laid on a faggot bed. The concrete blocks can be cast in situ or on the riverbank and handled with a motor crane.
Gabions, trenches and drains are built manually using local materials.
The road superstructure is made up of broken rock, big river stones and ballast.
The roadbed is prepared with a motor grader and a roller. After the work is finished the deposits are levelled and planted with forest species. The vegetation on the road embankments is restored with grass and trees.
The maintenance and repair works performed annually or periodically are intended to preserve the technical conditions and appropriate characteristics of forest roads and bridges. Subsidiary constructions are erected to provide good conditions for safe traffic all year round.
The planned maintenance and repair works are classified as follows:
a. maintenance works (LI)
b. current repair works (RC)
c. overhaul repair works (RK)
All three types of works (maintenance and repair, current and overhaul) are financed from production funds. Current and overhaul repair works for roads of category I, II, and in part III are performed with a motor grader as the main equipment, if a great amount of work is involved.
When maintenance works are intended to cover a large surface, especially on forest roads of category III or in narrow spaces on roads of category II, as well as when it is necessary to clean, to reshape the ditches and trenches for water draining and to remove snow on roads of all categories, the current technology uses the forest tractor TAF 650 as the "main equipment". It is adapted and equipped with auxiliary devices for road maintenance (bulldozer blade, trench digger, tipping bucket) and is known as TID (tractor for maintenance of roads).
The forest policy starts from the assumption that only a suitable density of forest roads can ensure sustainable forest management, which includes reduction in the loss of log volumes, appropriate sanitary fellings, and extraction of damaged trees and seedlings. The policy emphasizes that investments in necessary roads are a priority.
The above-mentioned operations according to which forest roads have to be designed are part of the overall forest management planning which is itself a component of a comprehensive land-use planning. Comprehensive harvest planning is essential in order to set the proper stage so that sustainable harvesting practices can be followed to space out the necessary investments and to avoid scheduling problems in road building. A properly prepared harvest plan should be completed to identify the permanent forest estate and occurred emergencies.
The requirements that roads must be located at the basis of the mountain slope, along the hydrographic network, the restrictions concerning the location on mountain slopes, where it was necessary to bypass large slopes on valleys, waterfalls, rocky or unstable zones, and the necessity to avoid land expropriation - all these resulted in great distances from the extraction point (1-2 km) and, consequently, high costs, high energy and material consumption as well as high labour cost.
The above-mentioned costs can be diminished by reducing the extraction distance by building supplementary steep roads, located as much as possible parallel to the roads at the bottom of the valley.
The techno-economic studies concerning the establishment of forest roads on the whole forest land, drawn up in the National Institute of Wood, arrive at the following conclusions:
· Depending on the width and angle of the slope, configuration, type and land stabilization the forest roads density varies from 14.2 to 32.4 m/ha/production unit and from 18 to 22 m/ha/forestry branch, compared to 9.8 m/ha which could be reached after the creation of the whole road network at the bottom of the valley, located on the hydrographic network; the extraction distance would vary from 600 m to 200 m compared with the present one of 1900 m estimated in 1989.· These extraction distances would create the possibility to use environmentally sound operations with suitable equipment.
Taking into consideration the restricted funds, the forest policy establishes the following priorities:
· to provide gradual access to the whole forest land in order to draw in the economic circuit the wood mass to be harvested;· to increase the road network to the benefit of a comprehensive management of the forest in terms of efficiency and observance of environmentally sound conditions;
· to rehabilitate the road network to increase speed increase, to improve the country 's development infrastructure, to arouse public economic interest, to promote tourism, etc.
This paper, with other ones, produced by Romanian specialists, has the aim to present the actual situation in Romania together with the problems encountered, such as:
· which is the optimum forest road density in hill and mountainous zones, observing environmentally sound conditions?· optimum parameters of road design, construction and maintenance?
· detection and diversification of permanent and available sources of funds for investment in the sustainable development of a forest road network.
