{"id":75541,"date":"2026-02-27T16:17:57","date_gmt":"2026-02-27T14:17:57","guid":{"rendered":"https:\/\/www.sweco.fi\/?post_type=showroom_cpt&p=75541"},"modified":"2026-04-16T09:36:06","modified_gmt":"2026-04-16T06:36:06","slug":"kalasatama-pasila-alliance","status":"publish","type":"showroom_cpt","link":"https:\/\/www.sweco.fi\/en\/projects\/kalasatama-pasila-alliance\/","title":{"rendered":"Kalasatama\u2013Pasila alliance"},"content":{"rendered":"
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Kalasatama\u2013Pasila alliance renewed infrastructure construction<\/h1>\n

Published 27.2.2026<\/p>\n

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The\u00a0 Kalasatama\u2013Pasila tram line was designed in the heart of a rapidly developing Helsinki. Sweco\u2019s infrastructure designers played an extensive role in the S\u00f6rk\u00e4n Spora<\/em> alliance, which reflected takt-based construction, the City of Helsinki\u2019s sustainability goals and coordination with multiple parallel projects. N\u00e4kym\u00e4 Oy<\/strong>, now part of Sweco, was responsible for environmental design in the Nylanderinpuisto and Vallilanlaakso areas as part of the Karaatti alliance. The Kalasatama\u2013Pasila project won the Environmental Structure of the Year 2025<\/em> award.<\/p>\n

Kalasatama\u2013Pasila delivered as parallel alliances<\/h3>\n

The Kalasatama\u2013Pasila alliance designed and built the line for Tram 13, connecting Nihdi, Kalasatama, the Kumpula Campus and Pasila. The approximately 4.5\u2011kilometre tramway was completed on schedule and under budget in 2024, and the journey now takes only 12 minutes.<\/p>\n

Kalasatama\u2013Pasila was Finland\u2019s first infrastructure project delivered as two parallel alliances. Sweco\u2019s designers participated in the S\u00f6rk\u00e4n Spora<\/em> alliance together with WSP and Destia. Their responsibility covered the section from Nihdi through Kalasatama along Hermannin Rantatie to Haukilahdenkatu. In addition, N\u00e4kym\u00e4 Oy, part of Sweco, was responsible for environmental design in Nylanderinpuisto and Vallilanlaakso as part of the Karaatti alliance.<\/p>\n

\u201cApproximately 100 Sweco experts worked on the alliance, designing the technical systems for the track, municipal engineering, streets, traffic, and earth and foundation structures,\u201d says Tero Savolainen, Sweco\u2019s Project Manager.<\/p>\n

According to him, the parallel alliance setup brought new elements to the familiar alliance model. Sweco has previously been involved in projects such as Raide-Jokeri, Kruunusillat and various phases of the Tampere Tramway. The team spirit was excellent: \u201cEveryone was on the same page on site, with no divide between designers and builders. We worked as one team!\u201d<\/p>\n<\/div>\n\t\t<\/div>\n\t<\/div>\n<\/div>\n<\/section>\n\n\n

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Kalasatama\u2013Pasila project (S\u00f6rk\u00e4n Spora alliance) in brief<\/h2>\n

Client:<\/strong> City of Helsinki\u2019s Urban Environment Division and Helsinki City Transport HKL (later Metropolitan Transport Ltd, KLOY)<\/p>\n

Services included:<\/strong> geotechnical design, municipal engineering and utilities, street and streetscape design, landscape design, bridges and special structures, tram track structures and technical systems, temporary traffic arrangements, safety and risk management<\/p>\n

Implementation period:<\/strong> 2019\u20132024<\/p>\n

Sustainability actions:<\/strong> CEEQUAL certification, application of BREEAM Infrastructure framework, over 80% recycling rate, reuse of excavated soil, use of low\u2011carbon concrete, diverse trackside vegetation.<\/p>\n<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t\t\t

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Designing a tram line in the middle of an active city<\/h2>\n

Kalasatama is one of Helsinki\u2019s busiest transport hubs and a major infill development area. According to Sweco\u2019s Traffic Design Project Manager Lotta Aittokallio, parts of the street areas in the Kalasatama Centre had to be pre-built for the tram, but changes were still needed.<\/p>\n

\u201cIn a dense urban environment you can\u2019t just add tracks on top of an existing street. Many parts of the surrounding area required complete reconstruction, including utility relocations.\u201d<\/p>\n

The tram line itself was only a small portion of the alliance. For example, the 50\u2011metre-wide Hermannin Rantatie was completely redesigned. \u201cThe entire street environment became more pleasant thanks to new green areas, pedestrian routes and cycling lanes,\u201d Savolainen notes.<\/p>\n

At Hermannin Rantatie, preparations were made for the future S\u00f6rn\u00e4inen tunnel by excavating the tunnel mouth 20 metres into the bedrock. \u201cThe entrance is covered and waiting, so future tunnel construction will not disrupt tram traffic for long,\u201d Savolainen explains.<\/p>\n

Significant coordination was required with Pasila\u2019s existing tram network and surrounding construction projects, from Redi\u2019s tower buildings to Hermannin Rantatie\u2019s housing developments and the Kruunusillat project in Nihdi. \u201cAt one point, three separate building projects were underway inside the turning loop in Sompasaari,\u201d Aittokallio recalls.<\/p>\n

Environmental design and a cohesive urban park landscape<\/h2>\n

The Kalasatama\u2013Pasila project also renewed the Nylanderinpuisto and Vallilanlaakso areas. N\u00e4kym\u00e4 Oy, now part of Sweco, led the environmental design in the Karaatti alliance, aiming to create a green, diverse and sustainable urban park environment.<\/p>\n

The park areas were completely reshaped, the tram line and a new cycling lane were integrated into the landscape, and the Kumpula Stream channel was restored to a more natural state. In Vallilanlaakso, stormwater management was improved with new open channels, and new recreational and walking routes were added. Recycled materials, diverse vegetation and KESY principles strengthened the ecological value of the area and enhanced urban biodiversity.<\/p>\n

Efficient temporary traffic arrangements on the tramway construction site<\/h2>\n

The wide project area required extensive temporary traffic arrangements. Sweco\u2019s solutions prioritised safety and the needs of pedestrians and cyclists. The area included bus routes and a special transport corridor.<\/p>\n

\u201cPhase-based takt production influenced the design of temporary traffic arrangements\u2014something still quite new in infrastructure construction,\u201d Savolainen says.<\/p>\n

Aittokallio adds that everyday convenience, community well-being and the cityscape were important. \u201cWe received particularly positive feedback on the temporary cycling lane and the roundabout at the Ty\u00f6pajankatu\u2013Hermannin Rantatie intersection. Residents even wished for it to become permanent!\u201d<\/p>\n

Sustainability guided the Kalasatama\u2013Pasila alliance<\/h2>\n

The City of Helsinki\u2019s sustainability goals influenced many aspects of the project, from circular economy principles to green infrastructure. 89% of excavated soil was reused on site, improving the project\u2019s overall sustainability. The added vegetation significantly reduces urban heat and manages stormwater, as verified by independent assessment.<\/p>\n

\u201cClimate change adaptation was also considered in the geotechnical design of Hermannin Rantatie,\u201d Savolainen explains. The street level was raised by around 2.5 metres due to flood risks near the sea. Because of weak soil-bearing capacity, a massive piled slab was required under the tramway. \u201cLow\u2011carbon concrete was used in the slab construction, reducing carbon emissions.\u201d<\/p>\n

The impact of sustainability measures was verified through CEEQUAL certification and the BREEAM Infrastructure framework.<\/p>\n

Header image:<\/strong> Kalasatama\u2013Pasila project, Aarni Salomaa
\nBottom image:<\/strong> Kaupunkiliikenne Oy<\/p>\n\t\t<\/div>\n\t<\/div>\n<\/div>\n<\/section>\n\n\n

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