Hailuoto Causeway will connect Riutunkari in Oulu to Huikku in Hailuoto. The 8,4 km long causeway will consist of 6.9 km road running on top of an embankment and two long bridges.

The bridge in Huikku will be located approximately one kilometre from Hailuoto. The total length of the bridge will be 767 metres, and its vertical under-clearance will be 18 metres where it crosses the shipping channel. The bridge in Riutunkari will be located to the north of the current ferry port. The bridge's total length will be 737 metres, and the vertical under-clearance of its central opening will be 5 metres.

The causeway will be built north of the existing ferry route, and it will replace the current ferry connection.

Construction work on the project started in spring 2024. The duration of the project’s construction work will be approximately two and a half years. The causeway will open in autumn 2026 at the earliest.

The cross-section of the road has been defined in accordance with general guidelines, taking traffic volumes into account.

If pedestrian and bicycle traffic is separated from vehicular traffic, an intermediate lane must be built between the roadway and the pedestrian and bicycle path. The lane would require widening the embankment and the bridges, which would increase construction costs significantly.

Recreational and tourist cycling takes mainly place in the summer season. The aim of the chosen solution is to optimize costs, in accordance with the number of road users.

There will be parking spaces for 15 cars and 3 buses, as well as parking for bicycles There will be no services in the area.

The causeway has been designed to blend into the landscape as well as possible. Because of that, there will be no lighting on the causeway.

The speed limit on the causeway will be 80 km/h. Due to the area's operations at the Riuttu end on Oulunsalo side, the speed limit is 60 km/h.

The average annual traffic is currently about 1,000 vehicles per day, of which heavy traffic accounts for about five percent.

The causeway is expected to increase traffic by about 400 vehicles per day.

During the construction planning phase, refinements have been made to the road plan, for example based on experimental structures and modelling during the construction planning phase, as well as more detailed dimensioning. The soil exchange and erosion protection at the sites of the bridges have been modified. These modifications have reduced both water turbidity and construction costs. Material from dredging has made it possible to reduce the size of the Artificial Island and to more accurate determine its placement.

This is taken into account in the planning and execution of the work. Disruptions to traffic will be minimized and traffic will be secured on both the ferries and the road 816.

The waterways remain in normal use during the project. Boating access through both bridge construction sites will be provided. During the open water season, the channel under Huikku Bridge will be open. During the construction of Riuttu Bridge, a temporary connection for boaters will be opened in autumn 2024, about one kilometre from Riutunkari.

Ferry traffic and ferry docks will continue to operate normally during construction. Some of the material will be transported by water in coordination with other water-borne transport.

The work sites are separated from the ferry ports and other traffic. At Riutunkari, queuing for the ferry, site traffic and pedestrian and cycle traffic are separated into their own lanes.

The traffic arrangements on Hailuodontie, as on the rest of the road network, are the responsibility of the North Ostrobothnian ELY Centre, which has prepared a traffic safety report on the transport of soil materials in cooperation with the Finnish Transport Infrastructure Agency and the City of Oulu. The impact of earthmoving on road safety will be reduced by lowering speed limits, using speed display boards, partial clearings, allowing mopeds on footpaths and cycle paths, paving roads and improving winter and summer maintenance.

The rock material used for the construction of the causeway comes mainly from Kiiminki. In total around 1.3 million m³ of aggregate will be needed for the causeway. The transport of rock material will be particularly concentrated in the first year of construction. Transport will also take place at night when there is less of a traffic.

The shallow water depth in the area does not allow for the transport of aggregate by barge to the causeway section to be built. In addition, road transport is less expensive and the risks associated with weather conditions are lower.

The bridges are located where the water depths and therefore the currents are the highest in the area of the causeway. The water depth at the bridges is in the order of 6–8 m. The water depth at the embankment sections mainly varies between 1 and 3 m.

The surface of the road on the connection line will be approximately 3.5 metres above mean sea level.

Construction work will be carried out all year round, but some work such as paving and bridge insulation is best done in the summer. The casting of the bridge decks is scheduled for the spring. The impact of winter conditions has been taken into account in the planning and scheduling of the work.

A wide range of new environmental surveys and flow modelling were carried out and previous studies consulted during the planning process. The causeway will change the environment locally but will not cause any notable harm to protected species or habitat. Direct impacts on the sea and its immediate surroundings will be minor. Protecting the environment is one of the most important objectives of risk management during the project.

The construction work causes some turbidity, which has been considered in the water permit’s terms. The turbidity is monitored regularly for example using aerial photography. In addition, close dialogue is maintained with environmental authorities.

Fisheries monitoring and planting of fry will be excecuted in accordance with the water permit decision, and dialogue will be maintained with environmental authorities. Loss of profits in fisheries will be compensated.

In the plans, the causeway has been designed to fit into the surrounding landscape as well as possible. The design takes the area's vulnerable and protected ecosystem in consideration. The challenging sea conditions were also factored into the structural solutions.

Once the road ferry service is no longer in operation, there will be no need for ferry ports and quays. So far, no party has been found to take over the maintenance of these structures, so they will be dismantled once the causeway has been completed. Traffic control equipment at the ports such as portals, railings and traffic lights will also be dismantled. Car parks will be built in the waiting areas of the ferry ports that will be decommissioned.

The alliance model is well suited to demanding projects that require particularly good cooperation between the different parties involved. For example, the constructor is involved in the design phase together with the designer and the client. The aim is both to improve construction productivity and to produce the final product (the causeway) quickly, with high quality and as cost-effectively as possible.

The procurement includes the implementation of the entire project. The alliance involves a development phase, which includes construction planning, an implementation phase during which causeway will be built, and a five-year ex-post responsibility phase. The alliance consists of GRK Finland Oy as the construction partner and AFRY Finland Oy and A-Insinöörit Suunnittelu Oy (formerly Plaana Oy and Ponvia Oy) as the design partners.

The alliance model is a form of implementation based on close cooperation between the various parties of a construction project. The key contracting parties, i.e. the client, the designer and the constructor form a joint organisation and are jointly responsible for planning and implementing the project.

In an alliance, transparency and common decision-making are the main principles. The goals of the alliance parties are aimed at serving the goals of the entire project through a commercial model that rewards or sanctions the project parties equally, according to the completion of the project in relation to pre-defined cost and key performance targets.

The Hailuoto project is estimated to generate about 500–600 person-years of employment in construction. In addition, the indirect employment effects on the region's economy are significant.

The authorization granted to the project by the Parliament is EUR 121 million. The Alliance Agreement's value is approximately EUR 105.4 million. The project is funded by the state, and the FTIA is responsible for its implementation.