Pig Detour. NS 20D crosses Whaley Street in Columbia, SC off of the Southern's R Line. NS 20D ordinarily runs on the Southern's W Line from Spartanburg, but a derailment on the W near Columbia forced several trains to detour from Spartanburg, SC to Charlotte, NC, then head to Columbia on the R Line. 20D will pass through Columbia quickly and take these stacks to the Port in Charleston, SC.