Infrastructure tunnel protects pipes and cables in new residential area

11 August 2015 Marine & Turnkey projects,  Weholite News

All pipes required for the infrastructure of a new residential area added to the city of Linköping in southern Sweden will be in an infrastructure tunnel approximately two kilometers long with an inner diameter of 2.2 meters. Since all maintenance and repair work will be done within the infrastructure tunnel, excavations in streets and settlements will soon become a thing of the past.

The Weholite infrastructure tunnel, approximately two kilometers long with an internal diameter of 2.2 meters, was laid in the Vallastaden district of Linköping in the summer of 2014.

Vallastaden is a modern, ecologically sustainable residential area of ​​the city currently under construction and will accommodate approximately 10,000 people. A residential fairground will also be built in the region.

Uponor Infra site chief Andreas Lillmals said, “All pipes and cables of the new residential area will be located within the Weholite infrastructure tunnel. "Water, sewage, regional heating and regional cooling pipes, as well as electricity and data cables, will pass through the tunnel." says.

In addition, the infrastructure tunnel will also contain solid waste collection pipes that absorb the waste of the region and carry it to the collection point with air flow.

Uponor Infra is responsible for the design, construction and laying of the infrastructure tunnel. The customer is the Technical Department of the city of Linköping.

Lillmals explains that Uponor Infra built its first infrastructure tunnel in Germany in the 1990s; "However, they were only a few hundred meters long."


Vallastaden Linköping Infrastructure Tunnel


No-Dig Maintenance

The big advantage of the infrastructure tunnel is that it will put an end to the familiar curse of cities: the occasional digging of holes in the streets.

“All maintenance work and work such as pulling new pipes can be done inside the tunnel. There will be no need to dig up streets or divert traffic. "Residents will not even realize that something is being done underground."

It is safe to work in a ventilated and well-lit tunnel. There is no need for heating, because the temperature underground is five degrees year-round.

Workers can enter the tunnel through reinforced concrete manholes built at the turning points. The tunnel also provides access to the properties on its route through branches.

“An infrastructure tunnel is a slightly more expensive solution than simply laying pipes and cables directly underground in the traditional way. However, pipe maintenance and adding new infrastructure is so easy that it will pay for itself in a short time,” explains Lillmals.

Christian Vestman from Uponor Infra Projec Services points out that being under infrastructure tunnel protection extends the maintenance intervals and lifespan of pipes and cables. “For example, valves do not rust because the pipes do not come into contact with groundwater. And when it is necessary to replace the cables, financially valuable copper-containing materials can be easily recovered,” comments Vestman.

The lifespan of the infrastructure tunnel itself is estimated to be at least a hundred years.

Is it on a greenfield vacant lot – or in the middle of the city?

Vestman explains that infrastructure tunnels are ideal for new, vacant sites where excavation is difficult due to groundwater or poor ground conditions.

“But an infrastructure tunnel is also a good solution in areas where construction has been completed and covered with pipe and cable networks. In pipe work, the key issue is not the pipe price. "Repeated excavation, asphalting, curb renewal and landscaping are the most expensive items."

Excavating underground infrastructure is particularly difficult. “When lower level pipes are replaced, it can be difficult to restore the ground to its original hardness during the backfilling phase. "This work may cause problems in the upper pipes laid after a few years."

Modular Solution Speeds Up Assembly

The “Lillmals” Linköping infrastructure tunnel drawings were laid on an empty land, which were only finalized after the assembly started. Therefore, the pipes and cables were subsequently pulled inside the tunnel,” he explains.

An infrastructure tunnel can also be built as a modular solution. In this case, the pipes to be located in the tunnel are pre-assembled at the factory. Once the infrastructure tunnel is in place, the pipes are connected to each other.

“The modular solution speeds up assembly,” Vestman confirms.


The tunnel attracted attention

Linköping is already planning a new infrastructure tunnel that will pass under the city center areas, including the main street.

“We plan to start work next summer,” says Vestman.

The Linköping example has also attracted attention elsewhere in Sweden. Visitors come from all over the country.

“As of now, we are in negotiations with about ten cities, some of whom want work to start next summer,” points out Christian Vestman.

• The tunnel is made of Weholite pipe, its length is about 2 km and its inner diameter is 2,200mm

• Water, sewage, district heating and district cooling pipes, electrical and data cables and a waste collection pipe system were laid.

• Infrastructure tunnel will serve residential area currently under construction for approximately 10,000 residents

• Uponor Infra is responsible for the design, construction and materials of the tunnel. Additionally, Uponor Infra supplies some of the pipes.

• Customer Technical Department of the city of Linköping