Arrow Dynamics started designing roller coasters with which pair of intertwined steel coasters at Disneyland?
Arrow Dynamics:  The Matterhorn Bobsleds at Disneyland was Arrow's first foray into roller coasters, in 1959. Matterhorn Bobsleds: The Matterhorn Bobsleds are a pair of intertwined steel roller coasters at Disneyland in Anaheim, California.
Matterhorn Bobsleds