breakthrough were successful; therefore the army developed new anti-tank obstacles for the border fortifications instituted during the Cold War. Nevertheless, the metal hedgehog was used as a quick road-block against wheeled vehicles. Russo-Ukrainian War In early 2022, during the Russian invasion of Ukraine, hedgehogs were used in conjunction with concrete barriers and other techniques to thwart Russian forces. The Ukrainian Railways repurposed new tracks to make hundreds of hedgehogs at 33 of its own shops and some other sites. The railroad estimated they had enough material for some 1800 hedgehogs. The Ukrainian military in Odessa, Kyiv and Lviv also made hedgehogs to be distributed to strategic locations. In Kyiv, hedgehogs from WWII were brought out of a museum and used at a roadblock. Technical details The hedgehog is not generally anchored to prevent movement, as it can be effective even if rolled by a large explosion. Its effectiveness lies in its dimensions, combined with the fact that a vehicle attempting to drive over it will likely become stuck (and possibly damaged) through rolling on top of the lower bar and lifting its treads (or wheels) off the ground. Industrially manufactured Czech hedgehogs were made of three pieces of metal angle (L 140/140/13 mm, length , weight ; later versions: length , weight ) joined by gusset plates, rivets and bolts, or welded together into a characteristic spatial three-armed cross with each bar at right angles to the other two, this pattern forming the axes of an octahedron. Two arms of the hedgehog were connected in the factory, while the third arm was connected on-site by M20 bolts. The arms were equipped with square "feet" to prevent sinking into the ground, as well as notches for attaching barbed wire. See also Caltrop Cheval de frise, a portable frame covered with many long iron or wooden spikes used in medieval times to deter cavalry. Dragon's teeth (fortification) Makibishi Sudis, an Ancient Roman stake which may have been lashed together to form a similar fortification References External links Anti-tank obstacles Area denial weapons