My sources did not elaborate. Perhaps it's an issue with the pilot plow or running gear operating through the reverse curves at Tacoma Dome Station. I do know the Charger has made a Portland roundtrip on the current line along Puget Sound. Also as I learned Saturday at Edmonds Station, two Chargers are operating push - pull on the Train # 510 / 517 Vancouver, B.C. roundtrip, which is currently using Superliners as well.