I think this is one of the longest tunnels in the world specifically built for bicycles. The 432 metre long tunnel was built by AG Tunnel, writes veier24.

The tunnel has a diameter of 5,5 meters. It has a pedestrian pavement, in addition two bicycle lanes, one in each direction.

During construction video:

AG Tunnel, although specialized in tunnels, had experience with tunnel maintenance, tunnel renovation and water protection. It is the first time the company did the tunnelling, according to the report.

https://www.veier24.no/artikler/430-meter-lang-sykkeltunnel-apnet-i-forde/522331

https://www.agtunnel.no/