The signage may not be entirely correct, as the State Highway Log indicates that SR 155 still turns south on Dayton Street to end at the intersection with US 97/WA 20. The State Highway Log shows that Spur 155 is what ends at the intersection with WA 215/Bus 97.
I can add this section between Dayton Street (WA 155) and WA 215/Bus 97 into the HB as WA 155 Spur.
