Taking the Slagsta car ferry from the island of Lovön over to the mainland is a pleasant, if not bracing experience. The wind is biting and the rain persistent but this is February in Stockholm. Two hours previously it had been snowing. The bright yellow car ferry is one of a handful of small scale links between the islands that make up the city, which has surprisingly limited accessibility for a capital of such importance. "The Saltsjö-Mälarsnittet effectively cuts the city into two pieces," explains Johan Brantmark, project director at the Swedish Transport Administration (Trafikverket). "It is difficult to live on the north side and work on the south side because the commuting times are too long. We have one high capacity road crossing – the Essingeleden link but it is hugely congested. Whenever there is any sort of incident it is a nightmare," he says.

To provide much needed resilience to the city, which is growing at the rate of around 40,000 people per annum, Trafikverket will oversee construction of a new highway running from Skärholmen in the south up to Häggvik in the north.

Twin tunnels will host 18km of the link, which will be created using drill and blast through the hard granite bedrock. The total road length is 21km and of the 18km of tunnel 16.5km is a continuous section.

At SEK 28bn (USD 4.2bn) the project will not be cheap but a tunnelled approach was deemed vital to preserve the environmental heritage of the area.

The new road runs near a UNESCO World Heritage site – Drottningholm Palace, residence of King Carl Gustav of Sweden, situated on the picturesque Lovön island, in Lake Mälaren.

Running beneath the Lake, and ensuring that the tunnel avoids any potentially fractured rock means that at its deepest point it dives to 60m below ground level.

"It was orignally planned as a three lane surface highway," says Brantmark. "Up until some years ago it was a tunnel that came out as a bridge across the straight in the northern part of Lovön, and then as part of the negotiation and planning process that bridge was taken away because of the visual impact that it would have and its intrusion into another natural reserve.

"So that made us decide to put it underground all the way," he explains. next steps

The next major step for the project is the final approval of the land acquisition plans expected in the summer. After this procurement will begin in earnest for some 50 contracts, using a mix of design and build and build only contracts. Contracts for two access tunnels at Skärholmen at the southern end of the link have already gone out to tender and prequalification is underway for two further packages. The biggest contracts to be tendered are the six build only packages for the tunnel and six design and build contracts for the major interchange points. Brantmark expects that in the next two years total value of contracts let will be USD 2.77bn. It is not surprising then that the organisation wants to see more international firms come into Sweden and Trafikverket has been hosting information sessions with contractors overseas. "We believe that the Swedish construction industry has lived life a little bit separate from Europe and from our perspective we see that as a problem. We welcome international competition and we are actively seeking that," says Brantmark.

Construction of the road tunnel will involve excavation of some 19 million tonnes of granite using drill and blast, a choice decided by the good quality rock and the dimensions of the three lane highway that is too wide and short for a TBM bore. "It is a permanently supported blasted tunnel but then we have an inner liner. We are putting in bolts and a 100mm shotcrete structure and PVC liner to make it absolutely watertight," says Brantmark.

Importantly the client is taking on the risk of unexpected ground conditions but Brantmark does expect that the environmental conditions, which are yet to be finalised by the country’s environmental court, will put conditions on allowable seepage into the tunnels. "We are afraid of too much groundwater drawdown and so the conditions will dictate the allowable seepage. We tackle that with pre grouting and that is a time consuming procedure," says Brantmark, nevertheless it must be priced.

"As the project evolves and we learn more about the job and the ground conditions we might be able to make changes but this is not something that we can guarantee. The price that we are looking for is one that includes this. Hopefully we can make it easier but it is something that needs to be done."

Of all the tunnelling contracts three are a similar size – those at Skärholmen, Johannelund and Sodra Lovö. Each require the excavation of around 1.5Mm3 of rock. Further packages at Norra Lovö, Lunda and Akalla also have significant volumes to be removed. Around 50 per cent of this will be taken away via barges from three temporary jetties, a move designed to reduce construction traffic. Trafikverket has already begun negotiating contracts to sell the rock.

"It is large volumes and needs environmental permits so whoever has contract needs to get permissions and it creates a level playing field for all of the contractors," Brantmark says. "Typically in Sweden we would make rock the contractors asset but we believe that could favour some contractors and that will not make it easier for international contractors to enter the country."

On the same theme Brantmark says that the building information model software has been created with a neutral platform so that contractors can use their own preferred systems. This project represents Sweden’s first major foray into the use of BIM and Trafikverket have looked to London for inspiration here.

"Crossrail have really moved far in this direction and we have been and visited with Crossrail and believe that there is a lot in Crossrail that makes sense." This is a major challenge for the scheme and represents a step change in how project information is used and stored. "On the design and build we require models back so that we can use them as a basis for procuring E&M works and for the as built documentation. It is very, very different. We have procured using models before on a running cost basis. This time it is a fixed fee basis so there are big requirements on the tender documents which makes these design and build jobs special."

Another key issue for Trafikverket is the quality control (QC) during construction. Brantmark is keen to see a proactive approach from contractors and urges them to appoint senior staff at a high level to the quality control role.

"My vision is to have contractors who come on the site with a QC attitude that is so strong that I can start to take my people off the site. On the City Tunnel in Malmö, the contractor had a quality manager worth the name. If we saw deficiencies somewhere we could just go to the QC person who had the ear of the director and that was enough."

Construction on the scheme is expected to ramp up in 2016, representing a busy year for contractors in the city as the metro is also set to be extended and a number of other tunnelling works for sewage and electrical cables are also expected. "If everything goes ahead as planned 2016 will be an extremely busy year for contractors, the volume of tunnelling works is increasing every day."

Doing the homework
For contactors interested in the construction conditions they need look no further than the City Line rail project, which is currently under construction. "This is the number one railway project in Sweden and if we could have done it earlier, we would have," says Kjell-Åke Averstad project manager for the City Line project at Trafikverket. His scheme is a 6km rock tunnel with two new station boxes that is set to double commuter rail capacity through Stockholm city centre. Known locally as the Citybanan project, the scheme will enable high speed rail to run through the city’s existing tracks creating better links with the rest of the country.

Earlier iterations of the project considered in the 1990s involving more surface lines were abandoned in favour of tunnels. "Of course tunnelling is more expensive but it is a much better solution," says Averstad.

Planning of the project began in 2000 and construction finally started in 2009. The creation of the rock tunnel has led to the excavation of 4Mt of rock and concreting work is advanced with over 70 per cent completed. Construction has been carried out under eight major civil contracts including two contracts for the new station boxes with linked tunnels, four further tunnelling contracts, a connection to the existing station in the south and a new railway bridge.

"They are all very different. We have design and build, build only, and different financial contracts depending on the subjects and what we thought we had in front of us," explains Averstad.

The station box contracts for Stockholm City station and the new Odenplan station with connecting tunnels were carried out under a cost reimbursable arrangement.

"We knew that from the beginning the preliminary design wasn’t the final design. We knew that you can optimise the design and work a lot with changing between concrete and rock and so on," he explains.

This meant bringing the contractors, NCC and Bilfinger respectively, in early and working together with client and designer to find solutions that could save time and money. "We put out a target price and if we go under that together we have a bonus system. Bonuses are very effective in this type of contract," says Averstad.

In 2007 the price level for the entire scheme was set at SEK 16.8bn (USD 2.52bn) and allowing for inflation it is today just under SEK 20bn (USD 3bn).

The approach has been a resounding success for Trafikverket. "We have 70 per cent of the money used so we are on track. The plan is that we will finish one year ahead of the date that we set at the beginning and we are forecast also to go under budget."

This is all the more remarkable considering the complex nature of the project and the challenges encountered along the way. One of which was the financial downfall of Danish contractor Pihl & Søn filed for bankruptcy in mid 2013. The contractor was engaged in two of the eight contract packages, including the largest package for the SEK 1.9bn (USD 280M) Söderström tunnel in joint venture with Germany’s Züblin, and the SEK 300M (USD 45M) railway bridge at Årsta.

Fortunately Zublin was able to deliver both contracts without its former partner. "Of course it was a problem but we managed to still do it," says Averstad. "We solved the problems in a way that has had local time delays but not impacted on the overall programme so we have succeeded in meeting the goal timescale."

Lessons from the scheme are all the more important given Sweden’s plans for major work.

Averstad credits good communication, strong planning, cooperation and getting stakeholder acceptance early. "From the beginning we had a high level of communication from the project with the surroundings and that was the most important part of the success in keeping the timescale.

"You must have a very competent management team – and some luck".