Sorterar skotaren bort det timmer som skördaren har tillrett?
The efficiency of the harvesters work is more often reviewed, than the work of the forwarders. In a local Stora Enso office the differences between the harvesters reported volume of timber, and the actual volume delivered to the industry had been noticed. Therefore, the decision was made to do a rev...
| Main Author: | |
|---|---|
| Format: | L3 |
| Language: | Swedish Inglés |
| Published: |
SLU/School for Forest Management
2009
|
| Subjects: |
| _version_ | 1855572037058166784 |
|---|---|
| author | Jansson, Lisa |
| author_browse | Jansson, Lisa |
| author_facet | Jansson, Lisa |
| author_sort | Jansson, Lisa |
| collection | Epsilon Archive for Student Projects |
| description | The efficiency of the harvesters work is more often reviewed, than the work of the forwarders. In a local Stora Enso office the differences between the harvesters reported volume of timber, and the actual volume delivered to the industry had been noticed. Therefore, the decision was made to do a review on the forwarders work.
The review was conducted together with a worker from Vmf Qbera, who is working daily with wood measurement, in order to get a valid evaluation of the logs. Eight sites were included in the survey, and on each site 50 logs were marked. Approximately one third of the marked logs were pulpwood, and the remaining logs marked were timber. The sites had been harvested by three different entrepreneurs.
At every site between 46 and 49 of the marked logs were found. There can be different reasons to why not all the logs were found. One likely reason is that the marked logs had been used as coasters for the piles, or that the numbers had been erased by weather and wind. There is also a possibility that the missing logs had been left on the site.
Possible source of error can be that the forwarder operators paid the marked logs some extra attention. They claimed afterwards that that was not the case. The marked logs were evaluated from what was visible. The possibility therefore exists that the logs contained hidden errors, which could have been detected by the forwarder operator. The forwarder operator would in that case have done the right thing, but it would have been noticed as wrong in the review.
The total amount of timber, compared to the wood measurement workers evaluation was 95 %. This amount can only be more than 100 % if a lot of pulpwood is placed in the timber-pile. The three different entrepreneurs in the review are also very equal when it comes to the amount of extracted timber, compared to the wood measurement workers evaluation.
The complete result for how much timber that is actually put in the pulpwood is
1,6 %. Beyond that, 3,6 % of the marked volume was not found. Some of the lost logs have probably been put in the wrong piles, but it can not be proven. It is an acceptable outcome which implies, that the cause from which less timber is delivered to the industry, is not the fault of the forwarder operators.
The reason for why less timber is delivered to the industry can depend on multiple causes. One reason can be the way the harvester lay the logs out during the harvesting operation. This substantially affects the work of the forwarder. Therefore, a similar review of the harvesters work would be interesting to conduct.
One of the entrepreneurs differs when it comes to a comparison between how much pulpwood has been put in the timber. This entrepreneur has a proportion of
7
4 % pulpwood put in the timber while the other two has a proportion below 1 %. The entrepreneur with the high proportion is probably too tolerant in their evaluation of timber. Stora Enso accepts a proportion of refused logs of 2,5 %. This implies that the two entrepreneurs that have a proportion below 1 % are too harsh in their evaluation of timber. In theory, they should be able to increase their timber proportion and still have an acceptable proportion of refused logs.
One of the entrepreneurs was marking logs with colour which would imply an easier way to work, for the forwarder operator. No clear differences between the entrepreneur using colour marking, and the other not using it could be seen. But in order to be able to prove that this is really the case, a more comprising review with more sites has to be conducted. |
| format | L3 |
| id | RepoSLU12294 |
| institution | Swedish University of Agricultural Sciences |
| language | swe Inglés |
| publishDate | 2009 |
| publishDateSort | 2009 |
| publisher | SLU/School for Forest Management |
| publisherStr | SLU/School for Forest Management |
| record_format | eprints |
| spelling | RepoSLU122942017-10-31T12:17:06Z Sorterar skotaren bort det timmer som skördaren har tillrett? Timber extraction efficiency : a comparative analysis Jansson, Lisa timmersortering skoteruppföljning timmerfortfall The efficiency of the harvesters work is more often reviewed, than the work of the forwarders. In a local Stora Enso office the differences between the harvesters reported volume of timber, and the actual volume delivered to the industry had been noticed. Therefore, the decision was made to do a review on the forwarders work. The review was conducted together with a worker from Vmf Qbera, who is working daily with wood measurement, in order to get a valid evaluation of the logs. Eight sites were included in the survey, and on each site 50 logs were marked. Approximately one third of the marked logs were pulpwood, and the remaining logs marked were timber. The sites had been harvested by three different entrepreneurs. At every site between 46 and 49 of the marked logs were found. There can be different reasons to why not all the logs were found. One likely reason is that the marked logs had been used as coasters for the piles, or that the numbers had been erased by weather and wind. There is also a possibility that the missing logs had been left on the site. Possible source of error can be that the forwarder operators paid the marked logs some extra attention. They claimed afterwards that that was not the case. The marked logs were evaluated from what was visible. The possibility therefore exists that the logs contained hidden errors, which could have been detected by the forwarder operator. The forwarder operator would in that case have done the right thing, but it would have been noticed as wrong in the review. The total amount of timber, compared to the wood measurement workers evaluation was 95 %. This amount can only be more than 100 % if a lot of pulpwood is placed in the timber-pile. The three different entrepreneurs in the review are also very equal when it comes to the amount of extracted timber, compared to the wood measurement workers evaluation. The complete result for how much timber that is actually put in the pulpwood is 1,6 %. Beyond that, 3,6 % of the marked volume was not found. Some of the lost logs have probably been put in the wrong piles, but it can not be proven. It is an acceptable outcome which implies, that the cause from which less timber is delivered to the industry, is not the fault of the forwarder operators. The reason for why less timber is delivered to the industry can depend on multiple causes. One reason can be the way the harvester lay the logs out during the harvesting operation. This substantially affects the work of the forwarder. Therefore, a similar review of the harvesters work would be interesting to conduct. One of the entrepreneurs differs when it comes to a comparison between how much pulpwood has been put in the timber. This entrepreneur has a proportion of 7 4 % pulpwood put in the timber while the other two has a proportion below 1 %. The entrepreneur with the high proportion is probably too tolerant in their evaluation of timber. Stora Enso accepts a proportion of refused logs of 2,5 %. This implies that the two entrepreneurs that have a proportion below 1 % are too harsh in their evaluation of timber. In theory, they should be able to increase their timber proportion and still have an acceptable proportion of refused logs. One of the entrepreneurs was marking logs with colour which would imply an easier way to work, for the forwarder operator. No clear differences between the entrepreneur using colour marking, and the other not using it could be seen. But in order to be able to prove that this is really the case, a more comprising review with more sites has to be conducted. Ofta görs det många olika uppföljningar på skördaren men det är inte lika vanligt med skotaruppföljningar. På ett lokalt Stora Enso kontor hade man uppmärksammat differenser i skördarens rapporterade timmervolymer och vad som faktiskt mättes in vid industrin. Därför togs som ett första steg beslutet att göra en uppföljning på skotarens sortering. Undersökningen genomfördes tillsammans med en virkesmätare från Vmf Qbera för att få en säker bedömning av stockarna. Åtta trakter ingick i försöket där 50 stockar märktes. Ungefär en tredjedel av dem var massaved och resterande timmer. Trakterna hade avverkats av tre olika entreprenörer. Vid märkningen antecknades om det var timmer eller massaved, längd och diameter. Efter att avverkningen var skotad kontrollerades alla vältor och det noterades i vilka vältor stockarna påträffades. Vid varje trakt hittades mellan 46 och 49 av de märkta stockarna. Anledningen till att inte alla påträffades kan vara att de låg som underlägg till vältan eller att siffrorna hade suddats ut p.g.a. väder och vind. Det finns även en risk att de kan ha glömts kvar på hygget. Möjliga felkällor till resultatet kan vara att skotarföraren har uppmärksammat de stockar som har varit märkta lite extra. De uppgav dock i efterhand att de inte ägnat någon större tankeverksamhet åt detta. De stockar som märktes bedömdes efter det som gick att se. Möjligheten finns därför att det har funnits dolda fel som skotarföraren har upptäckt. Han har då gjort rätt som placerat stocken i massaveden men det antecknas som fel i försöket. Vid en jämförelse mot virkesmätarens bedömning så ligger den totala timmervolymen på 95 % av mätarens. Det resultatet kan i princip aldrig bli mer än mätarens om det inte läggs mycket massaved i timret. De tre olika entreprenörerna i försöket ligger också väldigt jämnt. Det totala resultatet för hur mycket timmer som faktiskt sorteras i massaveden är 1,6 %. Utöver det är det 3,6 % av den totala volymen som inte har hittats. En del är förmodligen felsorterade men det kan inte bevisas. Det är ett godkänt resultat vilket tyder på att anledningen till att det mäts in mindre timmer inte beror på skotarens sortering. Anledningen till att det mäts in mindre timmer kan bero på något annat eller så kan det vara det sammanlagda av flera orsaker. En orsak kan vara skördarens sortering. Skotarförarens arbete påverkas avsevärt av skördarens sortering. Därför vore en liknande undersökning gjord på skördarens sortering en intressant jämförelse att göra. Vid en jämförelse med de olika entreprenörerna är det ett av lagen som står ut lite när det gäller hur mycket massaved som sorteras i timret. Det laget har en andel på över 4 % medan de andra två ligger under 1 %. Laget med den höga andelen är förmodligen för ”snälla” i sin bedömning när det gäller timmer. En godtagbar vrakprocent enligt Stora Enso är ca 2,5 %. Det betyder i sin tur att de lagen med en andel massaved i timret under 1 % är för hårda i sin bedömning. I teorin borde de kunna öka sitt timmeruttag och fortfarande ha en godtagbar vrakprocent. Ett av lagen använde sig av färgmärkning vilket borde underlätta skotarsorteringen. Det märktes dock inga skillnader mellan det laget och de andra. För att få ett ordentligt underlag för att det verkligen är så, behövs ett större urval med trakter. SLU/School for Forest Management 2009 L3 swe eng https://stud.epsilon.slu.se/12294/ |
| spellingShingle | timmersortering skoteruppföljning timmerfortfall Jansson, Lisa Sorterar skotaren bort det timmer som skördaren har tillrett? |
| title | Sorterar skotaren bort det timmer som skördaren har tillrett? |
| title_full | Sorterar skotaren bort det timmer som skördaren har tillrett? |
| title_fullStr | Sorterar skotaren bort det timmer som skördaren har tillrett? |
| title_full_unstemmed | Sorterar skotaren bort det timmer som skördaren har tillrett? |
| title_short | Sorterar skotaren bort det timmer som skördaren har tillrett? |
| title_sort | sorterar skotaren bort det timmer som skördaren har tillrett? |
| topic | timmersortering skoteruppföljning timmerfortfall |