Tank traps are fortifications which are designed to keep tanks and other armored vehicles from passing through certain strategic areas. Tank traps are also used to control motor vehicle access to vulnerable areas like protected parks, beaches, and forests. Some historic examples of these traps can be seen in some parts of Europe, left over from the Second World War, and modern traps can sometimes be seen near parks and reserves. Unfortunately for soldiers, these traps are not terribly effective against tanks, although they are certainly useful for preventing access by average vehicles in a non-military situation.
A classic tank trap is made by pouring heavy pyramid shaped fortifications from concrete. Typically, the concrete is poured over a large pad, which is designed to prevent tunneling and the use of explosives. The concrete pyramids are too large for tanks to go over, so the tanks must either go around them or figure out a way to go through them. Some traps exploit this by essentially funneling tanks into vulnerable areas where they can be picked off with the use of anti-tank weapons.
From a distance, a tank trap can look kind of like a strange set of teeth, which is why some people call them “dragon's teeth.” Many tank traps used multiple lines of these concrete fortifications, often staggered so that tanks would have extreme difficulties if they tried to penetrate the trap. The spaces between the fortifications would also be strung with barbed wire, concertina wire, steel rods, and other deterrents which would keep foot soldiers out in addition to tanks.
In parts of Switzerland, a tank trap is called a “Toblerone line,” in a joking reference to the Swiss chocolate bar of the same name. Toblerone bars traditionally come as a set of pyramidal chocolate pieces linked together at the base, and they do look rather like a single line of a trap. Switzerland maintains several traps including mobile traps which can be rapidly assembled to prevent invasion in the event of hostilities.
In a military situation, tools like heavy weapons can be used to batter a tank trap with ammunition so that the pyramids will be reduced to rubble. Most tanks are fully capable of crawling over concrete and steel rubble, so the trap poses a momentary obstacle, rather than a serious defense. However, if a trap is well defended by protected troops with armor-penetrating weapons, turning back and pursuing another route may start to seem quite appealing to the leaders of the tank division.