Arlington County has an extensive network of bicycle infrastructure, including 50 miles of shared-use off-street trails. These multi-use trails are generally 10 feet wide with a solid yellow line striped down the middle to separate users.
Constructive mathematics. Idea. Broadly speaking, constructive mathematics is mathematics done without the principle of excluded middle (or other principles, such as the full axiom of choice, that imply it).
Because the prefix con- means with or together, and the root -struct means to build or to assemble, the word construct is itself an example of its own meaning. The word constructive has a positive connotation.