Construction A thousand piles cannot be hit without being disturbed – Helsinki’s large bridge contract disturbs the daily lives of the residents for five years

Helsinki The 1.2-kilometer-long Kruunuvuorensilta, which leads from Korkeasaari to Kruunuvuorenranta, has spoken to Helsinki residents in recent years.

The renovation of the Hakaniemi area, which was originally a separate project, has received much less publicity. Now in the implementation phase it is the same entity.

“This connection can be compared to a housing company’s pipe repair, where new ones are worthwhile when renewing pipes – both for cost reasons and from the point of view of minimizing disturbance,” the project manager Ville Alajoki Says the city of Helsinki.

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In the case of crown bridges, “more” means, among other things, the demolition of the old Hakaniemi bridge completed in 1961 and the construction of a new, lower-than-expected bridge.

Hakaniemen A lot of new streets are being built in the area, which will also be connected to the tram connection from Hakaniemi to Kruunuvuorenranta, which will be opened in 2027.

The demolition of the old bridge is justified because of its poor technical condition and because its location and size no longer correspond to the current view of sensible urban planning.

When the bridge was completed 60 years ago, it was a few realized parts of an overall plan that, if widely realized, would have made From Helsinki to the motorway city In the spirit of Los Angeles. The most important thing for the current Crown Bridges project is that several hectares of land will be available for new construction – as much as the ramps to be demolished on the old bridge.

The giant project consists of two sub-projects, one of which focuses on the renovation of Hakaniemi and the construction of a tramway extending to Laajasalontie. The second subproject includes two large bridge contracts: Kruunuvuorensilta and Finkensilta.

Read more: “Who needs to achieve the Crown Hook better?” – The new bridge threatens to blow Siltavuorenranta residents in an unpleasant way

The implementation form of the former sub-project is an alliance, and the main implementer is YIT. In addition, the alliance includes the City of Helsinki and the design offices Ramboll Finland, Sitowise and Sweco.

The sub-project formed by Kruunuvuorensilla and Finkensilla is a complete contract implemented by a consortium formed by YIT and Create. On the Hakaniemi and Laajasalo side, the construction sites started in May, and construction of the Kruunuvuorensilla will begin in October.

Alliance The target budget was adjusted to EUR 401 million during the development phase. Of this amount, the construction of the tramway accounts for more than a third, or EUR 148 million. The rest consists of street work, the demolition of the old Hakaniemi bridge and the construction of a new one, as well as the transfer of existing municipal technology.

“Now, among other things, the production of pile tiles and municipal technical work is underway,” sub-project manager Aapo Urjanheimo He tells YIT.

“The construction of the new Hakaniemi bridge will be completed next year, after which the old bridge can be demolished. So this is the Hakaniemi bridge on the Sörnäinen side and not the stone-built Pitkäsilta, which of course is not affected. ”

Aapo Urjanheimo considers the site the most demanding of his career.

For example, Urjanheimo considers the transfer of old technology to be a very demanding work phase. Although a lot of effort has been put into planning, almost everything has not been possible to find out in advance.

In many cases, the exact location of the pipes and cables is only known at the construction site. In addition, care must be taken at all times to ensure that excavation can reveal contaminated land from past industrial activity.

The challenge nor is it facilitated by the fact that the soil in the area varies greatly: in places clay, in places excavated rock and largely “Helsinki moraine”, which contains old pieces of bricks and other remnants of human activity. For such difficult-to-penetrate soils, it is hardly possible to use bottom reinforcement methods other than drilling. The longest piles extend to a depth of about 20 meters.

Perhaps what makes the construction site especially special is that the work in Hakaniemi will have a strong impact on the daily lives of the people living in Helsinki for the next five years.

When a thousand piles are struck next door, it cannot be done without disturbing them. And when a seven-meter-deep pumping station is excavated in the immediate vicinity of traffic, safety must be guaranteed.

Massive bridge construction is included in both the Hakaniemi side and the Kruunuvuorenranta side subproject. The alliance led by YIT includes the Finkensilta line between Nihti and Korkeasaari and the 400-meter Merihaa bridge leading to Nihti.

Despite these rather demanding engineering structures, Aapo Urjanheimo names logistics and site congestion as the most demanding features of his site, even though the total area of ​​the site is about 15 hectares.

Sewage drains are made of concrete.

The concrete structures of the stormwater line are a rugged act.

A supported trench had to be made for the wastewater meter well.

On the opposite shore A second, almost equal construction site is being started, which will be implemented as a total contract by the work consortium TYL Kruunusillat formed by YIT and Create. The approximately 150 million contract includes the best-known part of the project, Kruunuvuorensilta. The most visible component of the bridge, which will be implemented as a cable-stayed bridge supported by composite beams, is a pylon rising to a height of 135 meters.

The design life of the bridge is 200 years, which is why high-strength concrete is used for bridge castings.

“The foundations are cast in steel, front-house-sized pots. In total, about 25,000 cubic meters of concrete are needed on this entire construction site, of which Kruunuvuorensilla has a dominant share: 17,000 cubic meters, ”, TYL Kruunusillat project manager Jari Humalajoki says.

“Before the foundations can be laid, preparatory work must be done, such as dredging and building bridge curtains.”

Although The project package includes two independent subprojects, which are connected by the creation of tram conditions: the total contract on the Kruunuvuorenranta side includes a bridge enabling traffic, and the contract on the Hakaniemi side includes the necessary street works and also the rail structure on the Kruunuvuorensilla bridge.

“Concretely, this is reflected in the sub-budget that is directly related to tram transport. That amount, approved by the council, is 326 million euros, ”says Ville Alajoki.

Crown mountain bridges

  • Developer: City of Helsinki.

  • Project schedule: 2021–2026.

  • Cost estimate: EUR 401 million (alliance target) + EUR 150 million (bridge contract).

Read more: Helsinki is facing decent tram years

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