Samenvatting
The Norwegian Directorate of Public Roads has been responsible for an expansive development of tunnels on the national road system. An understanding of how tunnels influence traffic behaviour is essential in order to ensure that tunnels provide safe and comfortable conditions for road users. This article summarizes the experience that has been gathered in Norwegian tunnels so far. Even though the results concern specific tunnels with typical Norwegian design, they should be applicable in many other countries where design standards and traffic levels are higher.