On 6 January 2026, a significant renovation will begin in the Vuosaari Tunnel, forcing the tunnel to close for about one year. During the renovation, traffic is rerouted to the official alternate route through Itäväylä–Kallvikintie–Niinisaarentie–Satamakaari–Vuosaari harbour. To ensure optimal traffic flow, the alternate route has undergone significant testing and improvement over the past year. Observations over this summer show that changes made to the route had already had a positive effect, despite some need for improvement. Further improvements have been planned for the alternate route as early as this autumn.
“The tunnel closure will cause additional traffic near the residential areas of Vuosaari. We will do everything we can to ensure a smooth flow of traffic during the renovation. Various tests this summer showed that the amended alternate route is fairly good as it is. Over the course of autumn, we will continue to adjust the traffic light cycles and make some other improvements to better consider the morning and afternoon peaks. At this point, I can say that we will get to test these further improvements in late October,” says Jukka Värri, project manager at Fintraffic.
In September and October, the alternate route in Vuosaari will see the following temporary traffic arrangements, which are expected to improve the traffic flow during the construction project:
- On the eastbound side of Itäväylä, the left-hand lane will be the only lane for driving straight, and the right-hand lane will only be for turning to Kallvikintie. This will make it possible to freely turn right from Kallvikintie for drivers heading east.
- The traffic light cycle in the Itäväylä and Kallvikintie intersection will be adjusted to allow for better flow of traffic through the intersection during rush hour.
- The bus stop south of the Kallvikintie and Niinisaarentie roundabout will be taken out of use. This will eliminate the slowdowns caused by stopping buses and allow for better flow of traffic. The lane passing the roundabout will also be opened for everyone.
- The speed limit on the section of street from the Kallvikintie roundabout to the Satamakaari intersection will be reduced to 40 kilometres per hour to ensure better predictability of traffic, smoother merges and lane changes.
Several improvements have been made to the Vuosaari Tunnel alternate route to ensure as smooth a traffic flow as possible during next year’s renovation of the tunnel. The most significant improvements have been the construction of additional lanes at the Itäväylä and Kallvikintie intersection and the Niinisaarentie and Kallvikintie roundabout. In addition, the Niinisaarentie and Porslahdentie roundabout and the Niinisaarentie and Satamakaari intersection have been improved to meet special transport requirements. The alternate route has also been placed on the highest level of winter maintenance.
Trials of the Vuosaari Tunnel alternate route were carried out this summer – traffic improved on the second day
Trials of the improved alternate route were carried out on 17–18 June 2025. The aim of the trials was to ensure that the improved alternate route is a reliable detour around the upcoming Vuosaari Tunnel construction site. During the trial, the tunnel was fully closed to traffic, which was directed to the alternate route.
During the trial, monitoring targets were the smoothness of merging from Ring Road III to Itäväylä, the functioning of new lanes at the Itäväylä and Kallvikintie intersection and the smooth flow of traffic at the Niinisaarentie roundabout, at the Satamakaari intersection, on Rahtarinkatu and on Kallvikintie.
Results showed that on the first day, travel times were significantly longer than normal, but on the second day, the flow of traffic had significantly improved as drivers had become accustomed to the alternate route.
“On the first day, travel time in the afternoon rush from the harbour to Ring Road III was roughly 17 minutes. On the second day, that time had fallen to slightly over 10 minutes, considering that the normal travel time is around 8 minutes. This shows that drivers adapted to the detour quickly and traffic flows had become clearly quicker,” continues Jukka Värri.
Outside the afternoon peak, traffic was almost normal. Only the peaks of lorry traffic from arriving ships caused occasional queues.
Traffic volumes grew especially on Kallvikintie, where the morning and afternoon traffic volume grew to 1.5 times of what is normal. The section of Itäväylä east of the Kallvikintie intersection grew by roughly 60 per cent. Traffic volumes on both days were close to the same.
Travel time on bus 560 grew on the section between the Rastilantie roundabout and the Itäväylä intersection by at most three minutes compared to a normal day. Conversely, the travel time between the Mellunmäentie intersection and Kallvikintie roundabout was slightly over one minute longer.
Testing of the alternate route involved various measuring points on the ground and driving through the route regularly with other traffic. Other sources of data include drone footage, Fintraffic traffic measurement stations and cameras, and TomTom. Particular points for observation were traffic flows during peak hours, pedestrian crossings, and functioning of the intersections.
Background information on the project
Vuosaari tunnel renovation project includes overhauling the technical systems of the tunnel leading to the Vuosaari Harbour in Helsinki, which have reached the end of their service life. In addition, the tunnel structures will be repaired and the drainage and fire-extinguishing water systems under the tunnel will be replaced. Fintraffic is responsible for the Vuosaari road tunnel's renovation project and for commissioning improvement work on the alternative route. The City of Helsinki and the Uusimaa ELY Centre are responsible for planning improvements to the alternative route.
