Most highway tunnels (including the Coentunnel and Zeeburgertunnel on the A10 ring road around Amsterdam) are category C tunnels, which means some hazmat allowed depending on the nature of the materials, the quality of the containment, and the volume transported. Notable exceptions are the Schipholtunnel (category A, fewer restrictions) near the airport and the Arenatunnel (category E, severely restricted) under the stadium.