Kuva: Metsäalan ammattilehti - Puuhuollon T&K¤tehon tuloskalvosarja 2/2015 10 February 2015 ......

Kuva: Metsäalan ammattilehti

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Background and aim of the study• Measures and weight limits for heavy vehicles were changed by the statute that came

into force the 1st of October 20131.• New limits enable higher gross weights as well as higher vehicles which means bigger

load spaces. • Earlier very typical heavy vehicle was a 3-axle truck and a 4-axle trailer resulting in 60

ton gross weight.• According to the new statute two new vehicle types such as 8-axle vehicle with

maximum gross weight of 68 ton and 9-axle vehicle up to 76 ton are accepted. Prerequisite is that 65% of trailer axles have twin tyres, otherwise maximum weights are remarkably lower, 64 and 69 ton.

• An interesting issue is that it was encouraged to start trials with even heavier or longer vehicles in order to produce knowledge if these bigger vehicles could result in better logistic efficiency and if they could be accepted on some part of road network.

• In many cases forest energy materials are rather light and volume demanding and could benefit of bigger load spaces when transported by trucks

• The aim of this study was to find out how those above mentioned new vehicle types can improve the efficiency of forest energy material transport

1 Asetus ajoneuvojen käytöstä tiellä 4.12.1992/1257, muutokset 6.6.2013/407

Metsätehon tuloskalvosarja 2/2015 10 February 2015 Antti Korpilahti 2

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Load spaces

• Lengths of vehicles and load spaces remained unchanged.

• Truck length can be 12 m in maximum including cabin.

• Combination length is 25.25 m and width 2.55 m.• Trailer can be 12 m backwards from the front axles’ or bogie’s turn point or pulling tap and

2.04 m to any point forward: For a square platform it means length of about 13.64 m.

• The sum of lengths of load spaces can be 21.42 m.• For instance: truck 7.8 m and trailer 13.6 m.

• Vehicle body height from ground varies depending on• Product mark and model, and air or leaf suspension.• Rim and tyre size.• Load space design and unloading device.

• Maximum height is 4.40 m, earlier 4.20 m.• Usually trailer body is about 10 cm lower than truck body.• Load space heights can vary about 2.9 to 3.3 m.

• Maximum load spaces are for a truck about 60 and for an ordinary trailer 100 m3.


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Fresh mass and solid volume of material

• Logging residues as well as stump wood are mostly spruce.• Small-size stem wood or tree sections are pine and birch dominated.• Forest biomasses, uncrushed or chips, are loose materials, and we have to calculate

solid volumes and then energy contents taking the moisture content into account.• For logging residues there is data from earlier studies1 covering wide range of moisture

content, from 25 to 65%. From this data an equation was generated to show the material fresh weight, kg/m3(solid), according to the moisture content (graph on page 6).

y = 0.1121X2 + 0.227X + 566.83

where

y = fresh weight, kg/m3(solid)

X = is moisture content, % (green mass basis)

• Because equivalent data or equations are not available for stump wood and small-size stem wood, fresh weights for those were calculated by the above presented equation derived from logging residues.

• To transform loose load volume of comminuted material (chips) into solid volume, material density of 40% in load was used.

1 Korpilahti, A. & Suuriniemi, S. 2001. Käyttöpaikallahaketukseen perustuva puupolttoaineen tuotanto. Metsäteho report 122.


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Energy content calculations• Energy contents of materials are calculated by equation1

Qnet,ar = Qnet,d x (100 - Mar) / 100 – 0.02441 x Mar

where Qnet,ar = calorimetric value of fresh material when delivered to power plantQnet,d = calorimetric value of dry materialMar = moisture content (%) of material when delivered0.02441 = energy needed to evaporate water, MJ/kg

• It is presented that calorimetric value of dry woody biomass varies 18.5 – 20 MJ/kg.• Because of differences of material density and chemical composition, calorimetric values differ

between fuel types. There are not fixed values for logging residues, stump wood or small-size stem wood, and therefore different values have been used in different studies.

• For this study calorimetric values were asked from several experts, and the following values based on laboratory determinations were selected, MJ/kg.

• Logging residues 19.23 • Stump wood 18.36• Small-size stem wood 18.84

• Coefficient one MWh equals 3600 MJ was used in calculations.

1 e.g. Alakangas, E. 2000. Suomessa käytettävien polttoaineiden ominaisuuksia


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Green density of logging residue

Data from several studies/Korpilahti

kg/m3 solid volume


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Example of energy calculationsfor logging residue chips

Load density Heating value of dry matter 19.23 MJ/kg

Moisture Weight 0.40 Values of fresh material

% kg/m3solid kg/m3

loose MJ/kg MWh/kg MWh/m3solid MWh/m3

loose MWh/t

20 616 246 14.9 0.00414 2.55 1.02 4.14

25 642 257 13.8 0.00384 2.46 0.99 3.84

30 674 270 12.7 0.00354 2.38 0.95 3.54

35 712 285 11.6 0.00323 2.30 0.92 3.23

40 755 302 10.6 0.00293 2.21 0.89 2.93

45 804 321 9.5 0.00263 2.12 0.85 2.63

47 825 330 9.0 0.00251 2.07 0.83 2.51

50 858 343 8.4 0.00233 2.00 0.80 2.33

55 918 367 7.3 0.00203 1.86 0.75 2.03

60 983 393 6.2 0.00173 1.70 0.68 1.73

65 1054 422 5.1 0.00143 1.51 0.60 1.43


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Data of forest energy materials• The following data was used in this study.• Starting points are moisture contents of materials that give basis to calculate energy

contents and material weights and densities on truck loads.• Here presented moisture values were used in earlier studies1 and their relevance was

checked in this study.

Logging residues Stump wood Small-size treesMoisture, % 47 37 40

kg/m3 825 728 755

MWH/m3 2.07 2.16 2.17

MWH/t 2.51 2.96 2.87

Uncrushed density, % 20 20 42

kg/m3 loose 165 146 317

Chip load density, % 40 40 40

Chips kg/m3 loose 330 291 302

1 Kärhä, K. et. al. 2010. Kiinteiden puupolttoaineiden saatavuus ja käyttö Suomessa vuonna 2020. Työ- ja elinkeinoministeriön julkaisuja 66/2010


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Logging residues, stump woodand small-size trees for bioenergy


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Uncrushed materials, 60 t vehicleVehicle own mass 31 t

• Energy trucks usually carry grapple loader on all the time, because it is needed also for unloading. Thus vehicle’s own mass is rather high.

• When transporting logging residues or pieces of stumps, a 60 t vehicle could not usually reach its carrying capacity even the load space was maximum, 160 m3.

• Small-size trees or tree section can be with branches or delimbed, and load density and volume can vary respectively. Here density of 42 % was used to describe energy wood from small-size trees.

Logging residues Stump wood Small-size trees

Load space, m3 145 145 90

Load (material), m3solid 29 29 38

Load weight, t 23.9 21.2 28.5

Gross weight, t 54.9 52.2 59.5

MWh/load 60 63 82


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Uncrushed materials, 68 t vehicleVehicle own mass 32,5 t

• Even if the maximum load space is about 160 m3, gross weight remains often below 60 t with logging residue and stump loads. It also means that we cannot benefit from 76 t vehicle’s bigger load carrying capacity.

• When having a 76 t vehicle the load space should have the size of 135 m3 to fully benefit from this vehicle’s 42 t loading capacity when transporting small-size trees or tree sections.


Load space, m3 160 160 115


Load weight, t 26.4 23.4 35.8

Gross weight, t 58.9 55.9 68

MWh/load 66 69 103


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Forest energy trucks


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Comminuted materials, 60 t vehicleVehicle mass 25 t


Load space, m3 105 120 115


Load weight, t 34.7 34.9 34.7


MWh/load 87 103 100

60 t vehicle’s loading capasity can be rather easily achieved when transporting chips.


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• When transporting forest chips with a 68 t vehicle, a load space from 125 to 140 m3 is large enough to fully utilize the vehicle’s 41 t load capacity.

• These sizes of load spaces have been rather common. The result of an enquiry1 2010 was that 66 % of chip and fuel peat vehicles had a load space in size class 121 to 140 m3.

• 68 t gross weight demands that a vehicle has 8 axles and in practise twin tyres on all axles of a trailer. This vehicle type was introduced 1 Aug 2013 when gross weights got a new statute.

1 Karttunen, K. et al. 2010. Puupolttoaineiden ja polttoturpeen kuljetuskalusto 2010. Metsätehon tuloskalvosarja 2/2010

Comminuted materials, 68 t vehicleVehicle mass 27.5 t


Load space, m3 125 140 135

Load (material), m3solid 50.0 56.0 54.0

Load weight, t 41.3 40.7 40.8


MWh/load 103.5 121.0 117.2


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Comminuted materials, 76 t vehicleVehicle mass 29,5 t


Load space, m3 140 160 155


Load weight, t 46.2 46.6 46.8


MWh/load 116 138 135

• A 76 t vehicle consists of a 4-axle truck and a 5-axle trailer.

• Maximum load space is 160 m3, from which about 60 on truck and 100 on trailer.

• Calculations of this study suggest that it would be necessary to have almost maximum size of load space when transporting forest energy chips.

• Utilizing modern vehicle designs such as a moveable axle group or liftable axles or steering axles at the rear end of a trailer this size of a vehicle can be well manoeuvrable also on forest roads and turnarounds.


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Chip transport vehicles

On left: Down tractor+semitrailer+center axle trailer. On right: Tipping place and chain-unloading device


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Maximum load space fully laden with comminutedmaterial

• This table shows that 76 t vehicle capacity would be fully in use, and when target is to have bigger loads we need other type of vehicles that are not yet allowed on roads.


Load space, m3 160 160 160

Load (material), m3solid 64.0 64.0 64.0

Load weight, t 52.8 46.6 48.3


MWh/load 132.5 137.8 138.7


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Bigger vehicles – HCT vehicles• As mentioned before, the new statute concerning vehicle measures and weights allows

trials of bigger vehicles for product and logistic development purposes. Trials can be accepted on roads having necessary bearing capacity and strong bridges. Vehicles must fulfil critical measures concerning traffic safety and trafficability on road network.

• The expression HCT meaning High Capacity Transport has been widely used to mean such vehicles or vehicle combinations that exceed the measures of national orders.

• In practise, HCT vehicles are longer and consist of more or different vehicle units that are not accepted for common use.

• Because gross weight of 76 t on road network is accepted in Finland now, our HCT vehicles will mean, for instance, this kind of vehicle combinations:

– Tractor + semitrailer + ordinary trailer• Gross weights 26+24+42 = 92 t

– Truck + ordinary trailer + center-axle trailer• Gross weights 26+38+18 = 82 t or up to 35+42+24 = 101 t

– 5-axle truck + trailer• Gross weights 42+42 = 84 t

• Detailed measures depend on technical demands and constraints and possibilities to fulfil those when transporting different materials, so above presented is to give same idea of the HCT vehicles.


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HCT vehicle designs• At the moment there are three types of HCT vehicles potential for forest energy

transport.

Tractor + semitrailer + trailer (or dolly and semitrailer) Length about 31 m Load spaces about 95 + 95 m3

Load weight about 60 t and gross weight 90 ton This configuration is known to be rather stabile (ref. page 21).

A challenge has been to find out vehicle measures that produce enough load on drivewheels and are standard vehicles according to them.

Truck + trailer + center-axle trailer Length and loading capacity about as above. Not so stabile as the ordinary trailer combinations; the best design and measures still under

search. Truck and trailer can be used as an ordinary vehicle combination when center axle trailer is

released.

5-axle truck + 5-axle trailer Standard measures 42 + 42 = 84 tons, but should get acceptance for bigger load space

than normal, about 170 m3

Good mobility in difficult circumstances.


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Typical 60 t 3 + 4-axle vehicle for chip transport and a possible configuration for 80 - 90 t HCT vehicle


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Bigger vehicles best on public roads

• 84 – 90 t vehicles could be best when transporting chips from terminal to power plant.– Efficient loading at terminal, short loading time.– Always driving on main roads.– Good roads – good driving circumstances, low fuel consumption, driving times well known.

• 5 + 5-axle vehicle can have advantages of its own.– Equal gross mass on truck and trailer guarantees good mobility and manoeuvrability.– 5-axle truck alone is capable to move on tight places but still has big a load.

• Stability measurements from test drives and simulation studies have been carried out for many different vehicle combinations in Sweden1 and also some for most interesting combinations in Finland2,3.

– Results show very good stability for tractor+semitrailer+trailer vehicles.– Combination having a center-axle trailer as the last vehicle has shown somewhat poorer stability– For a 5 + 5-axle vehicle preliminary simulations have been done this far and those indicate about

similar stability as tractor+semitrailer+trailer has.

1 Aurell, J. & Wadman, T. 2007. Vehicle combinations based on the modular concept. Nordiska Vägtekniska Förbundet, report no. 1/2007.2 Haataja et al. 2013. Pilot testing of high capacity transpor vehicles at Lappeenranta airport, Finland 25.6.2013. Oulu University, unpublished report.3 Väisänen, I. & Haataja, M. 2014. HCT-puutavarayhdistelmien kaksoiskaistanvaihtosimulointi. Oulu University, several reports, unpublished.


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Comminuted materials, 90 t vehicleVehicle mass 30,3 t

• Vehicle units: tractor + semitrailer + trailer• Gross weights 48 + 42 = 90 t• Load spaces 95 + 100 = 195 m3


Load space, m3 181 195 195

Load (material), m3 72.4 77.9 78

Load weight, t 59.7 56.7 58.9

Gross weight, t 90.0 87 89.2

MWh/load 150 168 169


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Transport starting from a terminal


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Transport cost calculations• Uncrushed materials

– 60 t vehicle: truck + trailer, 3 + 4-axles– 68 t vehicle: truck + trailer, 3 + 5-axles

• Comminuted materials (chips)– 60 t vehicle: truck + trailer, 3 + 4-axles– 68 t vehicle: truck + trailer, 3 + 5-axles– 76 t vehicle: truck + trailer, 4 + 5-axles– 90 t HCT vehicle: tractor + semitrailer + trailer, 3 + 3 + 5-axles

• Some information of calculations– Drivers work on two shifts having 3,750 working hours per year. This includes normal work time

plus overtime work 250 h/driver.– There are about 200 work days/year.– Forest energy and transport work is needed more during winter time than in summer. Transport

activity can follow this demand by having holiday times and transport to terminals during summer.

– No other costs (such as comminution) beside transport costs are included.– Costs are presented as €/MWh, but those should rather be used to describe differences of the

use of different vehicles than exact real life operation prices.


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Transport costs of uncrushed forest energy materials60 t vehicle

• Costs according transport distance, km• Functions

– Logging residue y = 0.0542x + 1.7961– Stumpwood y = 0.052x + 1.5923– Stemwood y = 0.0397x + 1.2065


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Transport costs of uncrushed forest energy materials68 t vehicle


– Logging residue y = 0.0504x + 1.74 – Stumpwood y = 0.0477x + 1.5267– Stemwood y = 0.0336x + 1.1131


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Transport costs of uncrushed forest energy materials60 and 68 t vehicles


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Transport costs of forest energy chips60 t vehicle


– Logging residue chips y = 0.0361x + 1.1889– Stumpwood chips y = 0.0307x + 1.0843 – Stemwood chips y = 0.0316x + 1.0944


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– Logging residue chips y = 0.0325x + 1.1348 – Stumpwood chips y = 0.0275x + 1.0397 – Stemwood chips y = 0.0284x + 1.048


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Transport costs of forest energy chips60 – 90 t vehicles


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This study was part of the BEST-program launched originally by FIBIC and CLEEN together. The program was funded by TEKES.

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Kuva: Metsäalan ammattilehti - Puuhuollon T&K¤tehon tuloskalvosarja 2/2015 10 February 2015 ......

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