Publikasjoner
NIBIOs ansatte publiserer flere hundre vitenskapelige artikler og forskningsrapporter hvert år. Her finner du referanser og lenker til publikasjoner og andre forsknings- og formidlingsaktiviteter. Samlingen oppdateres løpende med både nytt og historisk materiale. For mer informasjon om NIBIOs publikasjoner, besøk NIBIOs bibliotek.
1992
Forfattere
Reidar Skaar Halvor WesternSammendrag
Forest truck roads are necessary in order to carry out proper management of a forest area. In the Nordic countries there is now 400.000 km with forest truck roads. Based on a pilot study it was obvious that the conditions of the forest truck roads were not satisfactory from a road maintenance and vehicle transportation point of view.Unsatisfactory standards of bearing capacity, surface course, base course, geometric alignment were observed as major problem areas. Most of these problem areas might be solved by use of better methods and equipment for maintenance and rehabilitation of forest truck roads. Different methods and equipment for measuring the bearing capacity were tested.Use of the falling mass deflectometer (fig. 5) with a falling mass of 14 kg and a drop height of 1 m seems to be an effective method for measuring the bearing strength of forest truck roads. A simple method for analyzing gravel deposits out in the field is developed. This method makes it more relevant to put more emphasis on the quality and composition of the gravel material used for surface and combined surface/base course layers.Mixing on the road of two moraine materials which each has less satisfactory specification band is tried. The mixed material achieved an almost satisfactory specification band. The cost for transport, mixing and levelling on the road amounted to 20 SEK per m3 mixed material. Mixing of two moraine materials in the pit has also been tried. The cost of the mixing operation was 6,20 SEK per m3 mixed material.Research on surface and combined surface/base course layers with stone sizes until 100 mm showed interesting results. Use of such coarse materials give cheaper material and maintenance cost for the road. However, coarse materials might give increased cost for placing and levelling of the materials on the road. Coarse materials with maximum stone size of 70 mm seems to give good overall results on forest truck roads with small and average traffic, that is 0-30 vehicle passes per day.Production of crushed stone materials to be used on forest truck roads has been investigated. Crushing of moraine to 0-60 mm material by use of a mobile crusher showed a production of 53 m3 of crushed material per effective hour. The cost was calculated to 13 FIM per m3 crushed material. When crushing to 0-30 mm the production was reduced to 21 m3 and the cost increased to 24 FIM.Maintenance of fine gravelrich (0-20 mm) surface courses with farm tractor equipment is investigated. This equipment is effective when the task is to remove holes and ruts on the road surface which are not deeper than 3 cm. If the task is to remove deeper holes and ruts a 12-14 ton grader is more efficient. Maintenance of coarse (0-70 mm) surface courses requires a 14-16 ton grader. After the grading the road surface should be compacted with a 5 ton vibrating compactor. Compacting with a vibrating compactor equipped with rings (fig. 19) gave good results on coarse gravel materials.Use of bitumenous materials on forest truck roads has been investigated. On forest truck roads with little traffic spraying of a bitumenous emulsion gave almost maintenance-free road surfaces for until 7 years. On roads with average and greater traffic use of oil gravel can be economically justified especially on the steeper gradients.Trials with open top culverts indicate that these are efficient on 10-16% gradients but only on roads with so minor traffic that grading is very seldom carried out. Rehabilitation for forest truck roads with grader and wheeled front-end loader (shovel) is investigated. This resulted in two improvements of the front-end mounted implements used by the shovel.Forest truck road rehabilitation with farm tractor equipment has also been investigated in the project. This type of equipment is quite effective for light rehabilitation tasks.
Sammendrag
Det er ikke registrert sammendrag
Sammendrag
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Forfattere
Dan AamlidSammendrag
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Forfattere
Kåre Olav VennSammendrag
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Forfattere
Erik ChristiansenSammendrag
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Forfattere
Dan AamlidSammendrag
Det er ikke registrert sammendrag
Forfattere
Svein SolbergSammendrag
Registrering av skogens kronetetthet og -farge utføres i dag i mange land, og har sin bakgrunn i omfattende skogskader flere steder i verden i seinere år. Som en del av det norske overvåkingsprogrammet har de lokale skogbruksetater siden 1988 utført registreringer på fylkesvise lokale overvåkingsflater. Flatene er subjektivt utvalgt i grupper, hver med fire flater i ulike utviklingstrinn, hovedsakelig i blåbærgranskog. I 1992 er registreringer utført på 746 overvåkingsflater, med totalt 46000 trær. Det har vært en jevn, men ikke dramatisk, nedgang i vitalitet på de fylkesvise lokale overvåkingsflatene i femårs-perioden 1988-92, særlig på Østlandet. Siden i fjor har kronetettheten gått betydelig ned på Vestlandet (nordre del), og Østlandet har hatt nedgang både i kronefarge og kronetetthet. Nedgangen i vitalitet for hele materialet kan delvis ha sammenheng med tørke på Øst- og Sørlandet de siste to somrene, og orkanen på Vestlandet og i Trøndelag ved begynnelsen av året.
Forfattere
Tore SkrøppaSammendrag
Det er ikke registrert sammendrag
Forfattere
Tore SkrøppaSammendrag
Det er ikke registrert sammendrag