Double line (disambiguation)

Double line may refer to:


 * Double track, a type of railway involving running a track in each direction
 * Double line automatic signalling, a form of railway signalling used on the majority of double track sections in New Zealand
 * Double-lined mackerel, Grammatorcynus bilineatus, a species of Spanish mackerel
 * Double-lined spectroscopic binary, a type of binary star: see Binary star
 * Mythimna turca, common name the double line, a moth of the family Noctuidae
 * In algebraic geometry, a certain family of conics
 * In algebraic geometry, a singular line of multiplicity 2—a type of double curve