Amtrak's California Zephyr topping Soldier Summit? Think again! What you see here is Amtrak equipment assuming the role of the Rio Grande Zephyr. This 'dress rehearsal' for the demise of the RGZ and the beginning of Amtrak service between Salt Lake City and Denver via the Rio Grande occurred on February 8, 1983. Little did anyone know at the time, the Thistle landslide would alter these plans, postponing the Amtrak startup via the D&RGW by almost three months.