On Rio Grande’s Tennessee Pass, the SP Central Corridor crossed The Great Divide, a formidable obstacle to east-west rail traffic, in the 1990s. A new locomotive, the GE AC4400CW, was introduced to tame the 3% grades, hauling massive tonnage 24/7 at 10,000+ feet! This included coal & taconite trains at 13,000+ tons, double-stack trains, & a fleet of merchandise freights.