Two years with ETT

Two years with ETT

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The practical parts of the ETT project began in January 2009, since then the 30-meter long vehicle has continually transported roundwood from a terminal in Överkalix to the SCA sawmill outside Piteå.

The ETT modular system contains a number of technical innovations. Instead of a conventional trailer behind a truck, the system uses standard units of dolly, link and trailer. The trailer is made from a special type of steel that makes it considerably lighter than a traditional trailer.

The vehicle has a newly-developed braking system that applies the brakes to all wheels simultaneously – this is probably the first time in the world that this has been tested on a modular vehicle.

The study done by Skogforsk shows that diesel consump-tion per kilometer is somewhat higher than that of a conven-tional timber truck, but since the payload of the 90-tonne vehicle is over 50 percent greater, fuel consumption per transported tonne is 20 percent lower. Consequently, transport costs are considerably reduced.

Although an ETT rig is six meters longer than a traditio-nal timber haulage unit, the drivers report no problems with stability or maneuverability – in principle, the rig handles just like a 60-tonne vehicle.

Overtaking distance and time are naturally lengthened, but the overall impact of the ETT unit on road safety is probably improved, because only two vehicles are needed to transport the same quantity of timber normally carried by three conven-tional vehicles.

Claes Löfroth Tel: +46 (0)18-18 85 [email protected]

The ETT modular haulage rig has a gross vehicle weight of 90 tonnes compared with the 60 tonnes of a conventional vehicle. The unit, which has now covered 525,000 km and transported 106,000 tonnes of timber, has so far met its ambitious target – to reduce carbon dioxide emissions and fuel consumption by 20 percent per transported tonne without compromising on road safety.

Two years with ETTLower CO2-emissions and fewer

haulage rigs on the roads

1 + 1 = 3 Two ETT vehicles transport as much timber as three conventional timber trucks. This is both good for the environment and reduces costs.

Claes LöfrothGunnar Svenson Tel: +46 (0)18 85 [email protected]

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Road transport accounts for 25 percent of the total cost from stump to mill. In the past decade, transport costs have increased by 1-2 percent annually, partly because of longer transport distances to the user but primarily due to higher diesel prices. Transport also accounts for much of the carbon dioxide emissions from forestry.

One way of reducing carbon dioxide emissions while reducing transport costs, is to increase the payload of the haulage rig. This is why Skogforsk ini-tiated the ETT project. The aim was to carry out practical tests of a vehicle that can carry four stacks instead of the three in conventional vehicles. The name of the project was therefore One More Stack (En Trave Till).

Volvo Lastvagnar AB built the vehicle and, in January 2009, the new rig made its first trip from the terminal in Överkalix to SCA’s Munksund saw-mill outside Piteå. This is a distance of 170 km.

ETT – En Trave Till (One More Stack)

About the projectThe ETT project is run jointly by Skogforsk, the Swedish Transport Administration, the Swedish Transport Agency, the forestry sector, Volvo Trucks, Parator, the automo-tive industry, the Swedish Association of Road Haulage Companies and the National Federation of Private Road Associations. Around 30 organizations are involved.

The project began in 2006 and the practical tests started in 2009. These will continue until December 2011.

This report summarizes the experiences after two years. The vehicle has covered nearly 525,000 km – the equivalent of 13 times round the world!

The ETT rig in brief The unladen weight of the ETT rig is 23,400 kg. The payload is 64,000-66,000 kg depending on the season. In winter the load is lower because ice and snow can add 1,000–2,000 kg during a journey.

Timber truck Dolly Link Trailer

Axle load

Empty vehicle 5,200 kg 6,000 kg 3,710 kg 4,450 kg 3,880 kg

Max permitted 9,000 kg 19,000 kg 18,000 kg 24,000 kg 24,400 kg

Modular system growing

Dolly, link and trailer are examples of standardized modules according to the European Modular System (EMS). Modules can be quickly fitted together to create an optimal vehicle combina-tion for efficient transport according to the type of road, e.g. bigger combina-tions on large highways, shorter and/or more robust vehicles on minor roads of poorer quality.

ETT modular haulage rig Conventional timber truck* Total length 30 meters approx 24 meters Total weight 90 tonnes 60 tonnes Payload 65 tonnes 42 tonnes Number of axles 11 7 Axle load 8–9 tonnes 8–10 tonnes

* timber truck without crane.

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New steel tested in the trailerParator has built the trailer for the ETT unit. Most of the trailer is made from DOMEX 700 MC – extra strong, cold forming steel with a yield strength of 700 MPa. Normally, forest trucks are made from steel with yield strength of 350 MPa. The new steel, which is made by SSAB, reduces the weight of the trai-ler by approximately 300 kg, so payload can be increased instead.

EBS on all wheelsThe ETT rig is the first modular vehicle in the world that has an EBS (electronic braking system) on all axles in the combination. Manufactured by Wabco. A CAN router in the dolly and link allows brakes to be applied electronically to all axles on the vehicle simultaneously. Brake force and reac-tion are evenly distributed, giving a high degree of safety.

The left picture shows a vehicle component made from conventional steel. The beam is 15 mm thick. With DOMEX 700 MC, the same strength is attained with only 10 mm (right picture).

Higher fuel consumption per kilometerStudies show that the ETT modular haulage rig, on average, has consumed 0.54 liters per km. This figure is based on the rig transporting a full load to Piteå and returning empty to Överkalix. Fuel consumption has varied somewhat over the year, and was highest in winter.

In March and June 2009 and Octo-ber 2010, the ETT modular haulage rig was converted temporarily to a three-stack vehicle with a gross vehicle weight of 60 tonnes, i.e. in principle a conven-tional timber truck. This reduced fuel consumption to, on average, 0.43 liters per km over the same route.

But lower per cubic meterThe ETT vehicle uses more fuel per kilometer but, at the same time, is transporting a bigger load. Per tonne- kilometer, which is the relevant measure, fuel consumption and CO2 emissions have been distinctly lower for the ETT vehicle.

Considerably lower fuel consumption per tonne-kilometer

The reference vehicle shows the fuel consumption when the ETT vehicle was temporarily converted to a three-stack vehicle with a gross weight of 60 tonnes – i.e. in principle a conventional timber truck. Fuel was measured over the same route and distance as for the ETT vehicle.

”Sweden average” is the average fuel consump-tion for 400 timber haulage trucks according to a survey carried out by Skogforsk in 2008. The results are based on a mixture of driving on public roads (which generally give lower fuel consumption per kilometer) and forest roads. In addition, the study was based on a mixture of timber trucks and vehic-les with cranes. For the latter, fuel consumed during loading was included.

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Carbon dioxide emissions reduced by 180 tonnes in two yearsUp until the middle of December 2010, the ETT vehicle has made over 1,600 round trips and used 276,000 liters of diesel. A total of 106,000 tonnes of timber have been transported from terminal to saw mill.

If the same amount of timber had been transported with a conventional 60-tonne haulage rig (the reference vehicle as above), this would have required over 2,500 round trips and 347,000 liters of diesel would have been used. The difference is 71,000 liters, or 20 percent.

According to the Swedish Petroleum Institute, CO2 emission is 2.54 kg per liter diesel. Applying this assumption, the ETT vehicle has reduced CO2 emissions by a total of 180 tonnes in these two years.

Table 1 shows a calculation based on the transport of 1,000 cubic meters of timber between Överkalix and Piteå.

The fixed cost is higher for the ETT vehicle, SEK 700 per day (ten hours*) compared with SEK 600 for a conven-tional timber truck. The larger vehicle completes the assignment in less than four days, while the conventional truck takes nearly six days. Consequently the fixed cost for transporting the thousand cubic meters of timber is lower with the ETT vehicle. The same applies for the cost of fuel and wages. The overall dif-ference is approximately SEK 23,500 or SEK 23 per cubic meter.

Transport cost per cubic meter reduced by SEK 23Table 1. Comparative costs of transporting 1,000 cubic meters of timber between Överkalix and Piteå, using the ETT haulage rig and a conventional timber truck.

ETT haulage rig Conventional timber truck SEK SEK Fixed costs 3.75 days á SEK 700 2.650 5.75 days á SEK 600 3.500 Km cost 4.890 km 46.750 7.500 km 57.800 Driver, normal working hours 75 hours 20.400 115 hours 31.250

Unsocial working hours 30 hours 1.200 46 hours 1.850

Loading with separate loader 8.000 8 .000

Total 79.000 102.400

* For more details of the calculation, see, Arbetsrapport no 723-2010 from Skogforsk

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Road safetyIt takes longer time to overtake the ETT vehicle because it is approximately six meters longer than a conventional timber truck.

Skogforsk studied approximately 700 overtakings but recorded no anomalies in the form of dangerous or interrupted overtakings.

VTI, the Swedish National Road and Transport Research Institute, also carried out a study. Over a period of three months, one thousand overtakings were filmed. The time margin in relation to approaching vehicles is now being calculated.

There is another aspect of road safety. If the ETT haulage rig can transport a larger load, then a given consignment can be transported with fewer vehicles out on the roads. International research literature shows that this factor is very significant for overall road safety.

Issues still to be examinedRoad wearThe Swedish Transport Administration has carried out a larger study of road wear. Sensors to measure the load at different depths were inserted in the road at Räktforsen. No difference could be observed between the effect of the ETT haulage rig and that of other heavy traffic.

The results were expected, because it is the axle pressure that affects the road surface, and this is no higher for the ETT rig with its eleven axles than for a conventional vehicle with seven axles.

The ETT haulage rig in the forest The ETT haulage rig was also tested on forest roads. It encountered no problems with turning at normal turning points. However, this should be tested on more roads of varying standards.

Traffic environmentBefore 90-tonne vehicles are used on a larger scale, relevant bridges must be surveyed. Certain longer bridges may have to be reinforced.

Passing places, road junctions and other possible obstacles to the progress of a 30-meter vehicle must also be reviewed.

Truck scalesThe ETT haulage rig is equipped with scales that measure the axle weight via the air pressure in the suspension. The driver can see directly in the cab whether the permitted total weight or the axle weight is exceeded. The system has shown good accuracy, with a stan-dard deviation of a couple of percent. However, there have been some pro-blems with reliability. Further develop-ment is required.

Road safety is essential. Over a period of three months, one thousand overtakings were filmed with cameras mounted on the ETT vehicle. The time margin in relation to approaching vehicles is now being calculated byt VTI, the Swedish National Road and Transport Research institute.

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Expanding the experiment to include more vehicles would be desirable. This would provide valuable experience and allow the testing of new logistical solutions for timber transports from forest to mill, not least combined road-rail transports.

It is also important to learn more about how the vehicle functions in everyday traffic situations in larger-scale use.

From research to application

Claes Löfroth

A number of tasks remain. Road safety studies are to be completed, inclu-ding special studies of overtaking, interviews with fellow road users and drivers of the test rig.

A number of technical improvements to the ETT haulage rig will also be made in order to further reduce fuel consumption and to improve mobility.

Key words: Timber haulage vehicle, heavy transports.Layout: Inger PetréIllustrations: Ingegerd HallbergTranslation: Leslie WalkePhotos: Skogforsk unless indicated otherwise

© Skogforsk

ADDRESSESUPPSALA, Uppsala Science Park, SE-751 83 UppsalaTel. +46 (0)18-18 85 00

EKEBO, Ekebo 2250, SE-268 90 SvalövTel. +46 (0)418-47 13 00

UMEÅ, Box 3, SE-918 21 SävarTel. +46 (0)90-203 33 50

www.skogforsk.se

The road wear is expected to be no higher than that of other heavy vehicles. It is the axle pressure that affects the road surface, and this is no higher for the ETT rig with its eleven axles than for a conventional vehicle with seven axles.

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Two years with ETT