Braess's Paradox

Braess’s paradox is a proposed explanation for the situation where an alteration to a road network to improve traffic flow actually has the reverse effect and impedes traffic through it. The paradox was postulated in 1968 by German mathematician Dietrich Braess, who noticed that adding a road to a congested road traffic network could increase overall journey time, and it has been used to explain instances of improved traffic flow when existing major roads are closed.