Rio Grande in Color Volume 8: Hauling Freight over the Great Divide from Morning Sun Books is an all-color look at 1990s action on this mountain railroad. Tennessee Pass, the SP's Central Corridor crossed The Great Divide, a formidable obstacle to east-west rail traffic, through the Royal Gorge and over the pass. A new locomotive, the GE AC4400CW, was introduced to tame the three percent grades, hauling massive tonnage at 10,000+ feet in elevation. This included 13,000+ ton coal and taconite trains, double-stack intermodal trains and a fleet of merchandise freights.