Signs located near tunnel portals mostly indicate certain restrictions/mandatory behaviour with regard to the use of the tunnel.
Typically, regulatory signs at portals are used to indicate:
These regulatory signs can sometimes be grouped onto a single sign as given in Fig. 1.
Certain countries have a specific « tunnel » sign to which some of the above-mentioned information is added.
Information signs are usually also located near the tunnel portal, providing:
For tunnels with a height limit that is lower than that of the access road, there is also a sign indicating the maximum authorised height. This sign may also be accompanied by a physical obstacle designed to limit the risk of over-height vehicles hitting tunnel equipment.