Comparison of modeling approaches for evaluation of machine fleets in central Sweden forest operations

Figures & data

Table 1. Input data for machine costs calculations.

Input data	Harvester	Forwarder	Harwarder
Investment cost, million Euro	0.493	0.399	0.669
Value at the end of the life cycle, %	10	20	10
Interest rate*, %	2.99	2.99	2.99
Insurance costs, thousand EURO/year	2.5	1.6	2.5
Trolley, thousand Euro/year	5.25 *^2	5.25 *^2	7
Salary, EURO/hour	25.1	25.1	25.1
Extra salary for uncomfortable hours, EURO/hour	3.468	3.468	3.468
Working days/year	205	205	205
Shifts per working day	2	2	2
Hours/shift	7.6	7.6	7.6
Uncomfortable hours/working day	4.7	4.7	4.7
Diesel consumption, liters/PM15-h	17	17	17
Diesel price, EURO/liter	1.02	1.02	1.02
Oil consumption, liter/PM15-h	0.75	0.4	0.7
Technical Utility (TU), %	83	86	83
Machine cost, EURO/PM15-h	108.1	91.5	119

* Stibor 90 for January 2019 (Riksbank 2019) + 3%.

*² one trolley is assumed to cost 7 thousand EURO per year, and a TMS is expected to need, on average, 1.5 trolleys.

Table 2. Input data for the region’s four districts, as used in the AH. In the DO, all stands were used irrespective of district borders. All mean values are volume weighted.

District	Number of stands	Total volume, m^3	Total net area, hectare	Volume/stand, m^3		Mean stem volume, m^3		Mean forwarding distance, meters
				Mean	SD	Mean	SD	Mean	SD
1	135	128 326	528	951	886	0.37	0.11	387	272
2	265	407 852	1 908	1 539	1 812	0.36	0.14	416	253
3	255	550 774	2 731	2 160	2 093	0.34	0.11	410	252
4	389	497 371	1 948	1 279	1 236	0.43	0.15	372	214
All pooled	1 044	1 584 323	7 115	1 625	1 655	0.38	0.14	398	243

SD = standard deviation

Table 3. Analysus results from the two approaches when only one machine type (the two-machine system (TMS)) was available.

Variable	Detailed Optimization	Aggregated Heuristic
Number of TMS teams (n)	26	25.5
Mean utilization, % harvester forwarder	90 94	92 100
Total costs, million EURO	14.44	13.76

Table 4. Relative distribution (%) of costs for the two approaches.

Variable	Detailed Optimization	Aggregated Heuristic
Logging	90.6	89.5
Relocation	6.2	7.6
Traveling	3.2	2.9

Table 5. Results from the analysis of the two approaches when two machine systems (TMS and harwarders) were competing.

Variable	Detailed Optimization	Aggregated Heuristic
Number of TMS harwarders	15 18	14.5 18.2
Mean utilization, % harvester forwarder harwarder	87 93 94	90 100 100
Total costs TMS and harwarder, million EURO	13.92	13.47
Savings with harwarder, %	3.6	2.1

Table 6. Cost distribution in percentage (%) for the two approaches.

	Detailed Optimization		Aggregated Heuristic
Cost part	TMS	Harwarder	TMS	Harwarder
Logging costs	93.2	92.4	92.2	91.3
Relocation costs	4.5	5.5	4.8	6.1
Traveling costs	2.3	2.1	3	2.6

Figure 1. Total costs when the harwarder productivity was adjusted from 95% to 105%.

Figure 2. Total costs while the harwarder costs are adjusted from 95% to 105%.

Sveriges Riksbank. 2019. Sök räntor & valutakurser [Search interest rates and exchange rates]. Swedish; [Accessed 2019 Feb 26]. https://www.riksbank.se/sv/statistik/sok-rantor–valutakurser/?g5-SEDP3MSTIBORDELAYC=on&from=2011-08-23&to=2021-09-23&f=Month&c=cAverage&s=Comma

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