Unless somebody somewhere already has that routing decision cast in concrete and memoed to all parties involved, it could go either way and the dispatcher will decide based on traffic conditions at the time.

Eastbounds from Pasco normally run via the ex-NP through Empire, referred to over the radio as the "low side" or sometimes "low line." UP trains coming into town from Hinkle have no choice but to run on the ex-SP&S from at least Fish Lake to Scribner. If there are trains coming out of Spokane, inbound UP's will drop down the connector from Scribner to Marshall and get on the ex-NP. But if there's nothing coming out, UP inbounds can stay on the ex-SP&S and cross Latah Creek Bridge.

Other exceptions to the rule include BNSF's Lind Turn, which often leaves town via Empire so it can head directly to the W&I interchange at Marshall. And when there's a parade of heavyweights like coal and grain leaving town, a ZCHCPTL with enough power to pull the low side might get routed via Empire to get ahead of them.

If 4449 comes through Cheney and the crew has no operating problems and there are westbounds leaving Spokane, it's likely the 4449 will run via Empire and pull the 1 percent grade into Sunset Junction. If 4449 has operating problems and/or there's no westbounds coming, it very well could take the ex-SP&S through Overlook and enter town on Latah Creek Bridge.

As for plans cast in concrete, there was a steam trip about to leave Spokane westbound a few years back. Everyone figured it would go the low side via Empire because a tie gang was working on the high side near Overlook. A certain person clued another certain person into the fact that leaving via the high side would 1)give the train better public exposure as it crossed Latah Creek Bridge and 2)send the train around the more photogenic and famous curve above Marshall. A phone call was made, the tie gang was ordered to clear up at Overlook, and half the fans waiting on the overpass at Marshall were caught out of position as the train stormed up Marshall Canyon on the more appropriate route.