On a mechanical analogue of the Braess paradox

The Braess paradox states that adding a branching route to an already congested road might actually worsen traffic jams. An elegant mechanical analogue to this paradox has already been proposed (J. E. Cohen and P. Horowitz, Nature 352, 699-701 (1991)) which seems to defy many people's initial intuition. We examine the motion of this analog mechanical system in an attempt to make the counter-intuitive prediction more comprehensible, while also clarifying a misleading remark contained in this reference.