Intentional explosions are caused when armies fire artillery or when air forces drop bombs on enemies. Military engineers handle explosives and arrange intentional explosions during wartime. Intentional explosions are also used by civilians in "demolition". They break up old and obsolete buildings and bridges, and break rock and stone for construction. Explosions are made for activities such as mining, construction, and large-scale civil engineering projects such as building tunnels, roads, railways, and dams.