Stormwater management as part of Länsi-Pakila area renovation
Residents of Länsi-Pakila actively participated in the planning of stormwater management, streets, and traffic in their own neighborhood
Published on June 8, 2026
The redevelopment of Länsi-Pakila is a model example of resident-oriented urban planning. Concerns related to stormwater management were turned into positive collaboration when residents were engaged face-to-face through planning walks. Sweco’s experts listened to residents’ wishes regarding both stormwater solutions and improvements to traffic safety.
A large-scale redevelopment addresses flooding issues and strengthens stormwater management in Länsi-Pakila
The City of Helsinki’s Urban Environment Division (KYMP) and Helsinki Region Environmental Services (HSY) are simultaneously developing street and traffic systems, water services, and stormwater management as part of the Länsi-Pakila redevelopment.
“The main reason for the extensive redevelopment in Länsi-Pakila is the flooding problems that have persisted for nearly a decade, causing repeated damage and raising concerns about safety in the area,” says Janika Niemi, Project Manager at the City of Helsinki. According to her, residents’ concerns were fully justified. “Once the scale of the problem became clear, it was evident that the project could not be implemented as a conventional redevelopment.”
What began as a stormwater project for just a couple of streets quickly expanded into a multidisciplinary sustainable urban development project. In the end, more than 50 Sweco experts were involved, covering areas ranging from traffic engineering and water services to street design and project management.
“I was surprised at how quickly Sweco was able to respond when the project expanded significantly,” Niemi says. She describes the collaboration as smooth, as everyone was working toward the same goal. “Sweco’s experts were fully committed to the project and understood the importance of the issues at stake.”
The planning process took into account a wide range of perspectives, from natural environments to the circulation and reuse of soil masses. In addition, a large amount of technical infrastructure had to be fitted into a very limited street space.
“For example, in water services alone, an exceptionally large number of property connections for potable water, wastewater, and stormwater had to be designed,” says Erika Mäisti‑Hämäläinen, Project Manager at Sweco.
Resident-oriented stormwater planning
The layered development of the residential area presents challenges such as an insufficient stormwater sewer network and complex terrain conditions. Located in a low-lying area, it is difficult to find effective overland flood routes, which makes stormwater management in Länsi-Pakila particularly demanding.
“Many property access roads are also below street level, and the groundwater level is high in relation to building basements,” explains Salla Hostikka, Stormwater Expert at Sweco.
Because stormwater problems had persisted in the area for a long time, residents’ trust in the city and stormwater planners had weakened. Therefore, active communication with residents was essential to rebuilding trust and guiding the planning in the right direction from the very beginning.
“People who have lived in the area for a long time know exactly how floodwaters behave on the streets and how traffic flows between them. That kind of information is not available on our maps,” Niemi emphasizes.
Problem locations for stormwater were reviewed together during planning walks
Resident engagement included two public meetings, first during the street design phase and then during the construction design phase. However, the most important method of engagement was the planning walks conceptualized by Sweco, which the client adopted with an open mind and enthusiasm.
“During the walks, we met residents face-to-face and, instead of making assumptions, were able to directly ask what they wanted,” says Jani Päivänen, Interaction Specialist at Sweco. The joint walks ensured that planners understood what changes residents were seeking in stormwater management, traffic arrangements, and green infrastructure.
The walks were followed by an online survey where residents could comment on the plans. Mäisti‑Hämäläinen notes that she has never led a project with such extensive resident collaboration—and it paid off.
“The information gathered through different channels was highly consistent and reinforced the same message. Street design progressed more quickly because residents’ needs and wishes could already be taken into account during the planning phase, which reduced the number of objections.”
Problem spots in the stormwater system were identified together
Effective communication with residents made it easier for them to get in touch, resulting in dozens of calls and messages on some days. Niemi is grateful for the support provided by Sweco’s experts.
Close communication paid off, and the tone of the messages began to change. Residents also started sending messages of thanks, reflecting their appreciation that action was finally being taken.
“Residents appreciated that there was finally a team involved that truly understood their situation,” Niemi says. “Many hope that this approach could be applied to all city projects, and I personally intend to make planning walks a part of my future projects.”
How can traffic safety in Länsi-Pakila be improved?
Traffic management will address intersections perceived as unsafe by, among other measures, improving visibility and restricting parking.
Safe pedestrian crossing points will be reorganized.
Driving speeds will be reduced in line with residents’ wishes, primarily through traffic calming measures (such as speed bumps) rather than by narrowing streets.
Street greenery design will focus on a limited number of low-maintenance plantings, as residents see their own lush private yards as the most important factor for comfort and well-being.
Stormwater planning continues in the Länsi-Pakila area along Pakilantie and Haaganpuro
Sweco will continue from the Länsi-Pakila area renovation planning directly into related projects, including street and infrastructure design for Pakilantie and park and stormwater planning for the Haaganpuro area. Continuity is essential, as stormwater from a wide area in Pakila is collected and conveyed into Haaganpuro.
“In demanding stormwater planning, in addition to hydraulic flow modelling, environmental objectives are emphasized, such as protecting habitats of flying squirrels and brown trout,” says Hostikka.
Joint site walks will be repeated along Pakilantie, and 360-degree photographs and drone videos of the area will also be produced. These will allow residents to explore the site virtually as well.
“We want to help residents understand in every possible way what is happening in their own neighborhood,” says Päivänen. “That way, changes that may initially feel intimidating can become a positive, collaborative effort.”
For Janika Niemi, continuing with Sweco was an obvious choice. The expert team familiar to residents will largely remain the same, and their in-depth knowledge of the area will carry over into the follow-up projects.
“The area is already well in the hands of Sweco’s designers. Parts of Pakilantie and the Haaganpuro area were already included in the Länsi-Pakila renovation planning.”
Read another example of Sweco’s interactive planning in the article about Kaarina Market Square!