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

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

The causeway was built north of the ferry route, and it replaced the ferry connection.

Construction work on the project started in spring 2024. The causeway was opened for traffic in June 2026. The project continues with finishing works.

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 have required widening the embankment and the bridges, which would have increased 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 are 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 is 80 km/h. Due to the area's operations at the Riuttu end on Oulunsalo side, the speed limit is 60 km/h. Reduced speed limits are in place in construction areas during finishing work.

The average annual traffic between Hailuoto and the mainland has been approximately 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 were 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 were modified. These modifications reduced both water turbidity and construction costs. Material from dredging made it possible to reduce the size of the parking area and to more accurately determine its placement.

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 causeway is approximately 3.5 metres above mean sea level.

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.

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.

Now that the road ferry service is no longer in operation, there will be no need for ferry ports and quays. No party has been found to take over the maintenance of these structures, so they will be dismantled.

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 generated about 500–600 person-years of employment in construction. In addition, the indirect employment effects on the region's economy were 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.