Our system has double wire because the messenger wire bears more current than the contact wire can. This permits the TPSS' houses to be spaced further apart, and theoretically allows for larger LRV current draw (ie, faster acceleration, or longer trains).
As your quote points out, full dual-wire "stitched" catenary allows for higher speeds, too, because the contact wire can be kept more horizontally straight (parallel to the ground). At higher speeds, a single wire would sag into a catenary curve (math term - where the system gets its name) and the pantograph would bounce up and down.
As your quote points out, full dual-wire "stitched" catenary allows for higher speeds, too, because the contact wire can be kept more horizontally straight (parallel to the ground). At higher speeds, a single wire would sag into a catenary curve (math term - where the system gets its name) and the pantograph would bounce up and down.