Renewal of the northern underpass in Oulu and related traffic arrangements

About the client and project

The renewal of the northern underpass will be completed as a joint project involving the City of Oulu, Oulu Waterworks and the Finnish Transport Agency as the clients. The Finnish Transport Agency is represented in the project by Juhan Tyrväinen, the City of Oulu by Vilho Vanhatalo and Oulu Waterworks by Jouni Lähdemäki.

The contract encompasses the replacement of the deteriorating Heikinkatu underpass with a new structure and the construction of an additional track on the bridge. The old bridge for pedestrian and bicycle traffic will be replaced with a new one. Additional lanes for road traffic will be constructed on the route passing under the bridge.

Challenges and problems involved

The environment is very challenging for construction. All northern Finland’s train traffic passes along the bridge, and the route under the bridge is one of the busiest in central Oulu. Construction work must be coordinated with pedestrian and bicycle, vehicle and rail traffic.

The street and track environment around the bridge is full of third-party cables, pipelines and other devices and structures which have required a great deal of investigation and enquiries.

The goal has been to keep the routes open for all transport modes throughout the project. As regards rail traffic, no traffic interruptions have been scheduled for the construction of bridge blocks. According to plans, the only actual traffic interruption will take place during the casting of the bridge block separator in autumn 2017. As for road, pedestrian and bicycle traffic on the route passing under the bridge, the interruptions have been limited in number and scheduled for night-time hours.

The technical work on the bridge is challenging and calls for contractors who are proficient in various special techniques.

Welado’s solutions

The contract type and scope of the contract areas were determined jointly with the client. The project was originally designed to be completed as several smaller contracts. During the planning process, the parties found that a single contract would facilitate the overall management of construction since the various engineering tasks were closely dependent on each other.

In 2016, preparations for the renewal of the underpass were made with each client regarding rail work, street work and municipal engineering work. The contracts involved track changes around the bridge, installation of pillar foundations for the electric railway, investigation and unearthing of cables running under the bridge, as well as preparatory work in the streets surrounding the site.

The skills requirements for contractors participating in competitive tendering were defined jointly with the client. This ensured the success of the tender and helped to select professional contractors for the project.

Welado, the client and other stakeholders jointly planned and specified the general conditions for maintaining the area’s traffic connections as well as the methods used for rail traffic and related systems, street traffic and pedestrian and bicycle traffic.

The project included numerous challenges, such as the power outages required for the construction of the electric railway system in the bridge area. Planned power outages in the railway electrical line would have cut the traction power in most parts of the Oulu passenger train yard. As a solution, Welado suggested to the client that the contractor’s tasks include the construction of the required neutral sections which would enable a local voltage cut to be created in the required bridge area. The winning contractor’s work plan was, in part, based on the possibility to shut the voltage using the neutral sections constructed in accordance with the requirements of the invitation to tender.

Throughout the project, Welado has looked after the interests of all clients regarding the detailed schedule, quality and costs. The expertise of Welado’s staff has proved useful especially in the coordination of technical construction and design and in safety control.


The measures described above helped keep the traffic connections in operation, minimize disturbances to traffic and carry out construction work as planned.

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