A SUPER 1803-2 played a crucial role in the construction of a latter-day Noah’s Arc on Spitsbergen.

The “Svalbard Global Seed Vault” was built in the permafrost soil of the Arctic archipelago over the past few months. The vault is a depository for plant seeds that is intended to preserve the biodiversity of our planet. Scandinavian construction firm Lemminkäinen surfaced an area of 1,600m² with a special soft asphalt that will retain its material properties in the long term despite a constant temperature of -18 °C.

120m tunnel in the permafrost soil

In the summer of 2007, construction machines and personnel were marshalled at the site on Spitsbergen – part of the Svalbard archipelago – to create a 120m tunnel beneath metre-thick layers of ice and sandstone just 800 kilometres from the North Pole, near the small town of Longyearbyen. The tunnel connects to three areas in which plant seeds from every continent have been stored since February 2008.

Lemminkäinen already built northernmost airstrip in the world

Scandinavian construction firm Lemminkäinen paved asphalt in the access tunnel and the storage aras. The Norwegian branch of one of Scandinavia’s largest construction companies already was awarded a prestigious contract on Spitsbergen back in 2006 (see RoadNews issue 08). Beneath the sun of the polar summer, Lemminkäinen rehabilitated and enlarged the northernmost airstrip in the world – also located near Longyearbyen – with machines from the WIRTGEN Group, including a VÖGELE dash-2 generation paver, the SUPER 1900-2.

Soft asphalt for tough conditions

In the access tunnel and storage areas of the Seed Vault on Svalbard, a 4cm thick layer of soft asphalt (MA 11) was paved (see Excursion “Soft Asphalt – Just Right for Arctic Temperatures” on page 18). This special mix is perfectly suited to the Arctic climate. During the paving process, the ambient temperature outside was roughly +6 °C, a typical midsummer temperature on Svalbard. In the 6m wide tunnel, asphalt was paved under permafrost conditions in two 3m strips with an AB 500-2 Extending Screed in TV version. The narrow pave width was dictated by the logistics: the paver had to be supplied with mix by a wheeled loader as the tunnel’s low ceiling did not allow feed of the paver by tipping lorry. Of course, this resulted in a lower laydown rate than normal. The relatively narrow pave width was chosen so that paving could nevertheless be carried out continuously.

Manoeuvrability a key advantage

Operating in the tunnel and each of the 300m² areas required a lot of skill and a highly manoeuvrable paver. In this respect, the Lemminkäinen team was able to make full use of the wheeled SUPER 1803-2. The tight turning radius of just 6.5m (outside), combined with the paver design with no projecting elements and a good view of all corners of the paver from the operator’s platform, greatly facilitated the paving team’s work.

Uncomplicated grade and slope control

Grade and slope control was handled by NIVELTRONIC® Plus in combination with a sonic grade sensor. The prepared base served as a reference for grade control. Thanks to the non-contacting operation and flexible attachment of the sensor on a telescoping arm, the sonic sensor could remain mounted when moving the paver in the tunnel and did not limit the machine’s manoeuvrability at all.

Ever ready thanks to NIVELTRONIC® Plus

Additional benefits of the VÖGELE Grade and Slope Control System came to light during the paving work, such as the system’s ease of installation. The automatic sensor detection function immediately registers the type of sensor connected, thus ruling out faulty operation. Another benefit is the Quick Set-Up feature, which defines and stores the picked-up actual value as the set value. Thanks to this feature, the paver was ready for work again straight away each time it had been moved in the tunnel. This quick readiness was extremely important for the success of the project in the light of the exceptional logistics.

Simple operation thanks to ErgoPlus®

The ErgoPlus® operating consoles greatly facilitated operation with their self-explanatory symbols and logically arranged user menu. It was extremely important for the push-buttons and displays to be perfectly visible in the dim light of the tunnel. This was no problem thanks to the backlit display of the ErgoPlus® consoles.

Effective sound insulation

Low noise emission has already been an important issue in Scandinavia for a long time. When paving in the tunnel, the SUPER 1803-2 was able to trump in this respect as, upon its development, the VÖGELE engineers had substantially reduced the noise levels operators are exposed to. Measures were taken such as an effective noise insulation and the choice of a quiet engine. And if the paver is operated in ECO Mode, as was the case on the Svalbard project, noise emission is reduced even more. This meant that the team from Lemminkäinen was never exposed to high levels of noise pollution.

Paving team thrilled with its SUPER paver

The 7-man team from Lemminkäinen under the supervision of Gunnar Unstad was extremely satisfied with the reliability of their SUPER 1803-2: “We're glad that everything went so well. A machine failure would have caused enormous consequential costs due to the complex logistics. But we have 100% faith in the quality of VÖGELE pavers and haven't been disappointed yet.”

Soft Asphalt – Just Right for Arctic Temperatures

The soft asphalt (MA 11) used in the Svalbard Global Seed Vault is particularly suited for areas with permanent ambient temperatures below zero. The mix with a binder content of 4.7% (±0.5%) has optimal properties at subzero temperatures and features a very long service life. Therefore, it comes as no surprise that such mixes are well-known in northern Scandinavia and Alaska, for example, and their use is very popular.

Asphalt with high binder content

The aggregate used was stone with a maximum grain size of 11mm. The binder was a fluxed bitumen with a viscosity of 10,000mm²/sec. (approx.) at 60 °C. Furthermore, the binder content is higher in soft asphalt than in conventional asphalts. Its exceptional material properties also have a positive effect upon easy paving of the mix which, as the team from Lemminkäinen confirmed, could be handled impeccably with the SUPER 1803-2.

Only suited for Arctic temperatures

Certain factors, however, must be observed when using soft asphalt. If the ambient temperature rises above +5 to +10 °C for an extended period of time, the asphalt loses its load bearing capacity and longevity. Then, as soon as it is exposed to heavier weights, the compressive stress immediately causes deformation of the soft asphalt pavement.

Svalbard Global Seed Vault: Depository for Plant Seeds

With the Svalbard Global Seed Vault, the Global Crop Diversity Trust is pursuing the goal of storing the seeds of as many crop types as possible, thus preserving varieties whose existence could be endangered through natural catastrophes (such as infestation by pests or climate changes) or other events (exposure to genes from genetically manipulated plants).

Space for 4 million seed types

The bunker-like facility on the island of Spitsbergen, part of the North Atlantic Svalbard archipelago, extends to a depth of 120m into a former coal mine. Inside in three areas, seeds will be stored of up to 4 million crop types such as rice, maize, beans or potatoes. Almost every nation plans to send seed specimens to Spitsbergen, or has already delivered initial specimens. The areas are located 120 metres above the current sea level and should remain safe even in the event of a drastic rise in the sea level resulting from climate change. The areas are equipped with reinforced concrete and thick steel doors and would thus be able to withstand the effects of a nuclear war or a plane crash.

Storage in permafrost soil

The plant seeds are stored at a cool -18 °C, generated by a cooling system. This means that the seeds can be preserved for some 55 years to 10,000 years, depending on type. Old seeds will be constantly replaced with young ones. “It's a highly protected area in a very quiet corner of the world. And there is permafrost here, which means that even if there is a technical problem and the cooling system fails, the temperature would never rise above -3.5 degrees Centigrade”, says Magnus Treiden, a member of the research team.

The opening ceremony of the Svalbard Global Seed Vault with construction costs that amounted to 30 million euros took place on 26 February 2008. The lion's share of the costs was financed by the Bill and Melinda Gates Foundation.

Complex Logistics

Despite the difficult conditions in supplying the paver with mix, the 7-man team from Lemminkäinen only needed a total of 12 hours to lay the 190 tonnes of asphalt. The preparations for this job were far more time-consuming. The project was backed by an impressive logistics solution, so that the asphalt paving on the island of Spitsbergen could be successful. Almost 1,200km from the European mainland, the island has no construction machines or materials and no mixing plant.

Therefore, all equipment, machines, resources, spares, wearing parts and other materials had to be delivered to Spitsbergen by ship from Tromsø on the Norwegian mainland. A modern freighter can cover this distance in 60 to 65 hours. This is also how the mix was delivered to the job site. The soft asphalt was shipped in special containers that were so well insulated that the asphalt that left the mixing plant with a temperature of 130 °C arrived at Spitsbergen still with a temperature of 100 to 110 °C. The mix was unloaded from the ship into feed lorries and subsequently delivered to the paver inside the tunnel by wheeled loaders.

In total, some 500 tonnes of asphalt were shipped, far more than was required for the surfacing of the Svalbard Global Seed Vault. The rest of the asphalt was used for road construction on the island.