Fairchild (like many Air Force bases) hasn't had rail service (regular or otherwise) for quite a while. The spur just passes through the base; there aren't any additional spurs to the fuel tank farm or anywhere else on base, nor are there any locations along the spur for offloading anything that might be delivered by rail. Most AF bases receive fuel by pipeline or by truck anyway; anything else is either delivered by truck or by cargo aircraft (some of the larger bases still receive shipments by rail, but smaller bases like Fairchild or Kirtland AFB here in Albuquerque no longer do).