Crews are seen wrapping up one of their biweekly power-washing sessions on one of MRL's SD70ACe helper sets at the Helena Roundhouse. After 48 hours of hard runs up and over Mullan Pass, even these cleaner burning Tier-II compliant diesels begin to cake on dirt and exhaust fumes. The EMD SD70ACes may be cleaner running than MRL's predecessor SD45 helper sets, but the ~3500' long Mullan Tunnel still pushes the limits of their efficiency, resulting in sooty buildups after each passage.
There are times when many engines, cars or cabooses are concentrated in a location. Such sites are for storage, economic reasons, active power needs or for rebuilding. For others, wear and tear have brought their usefulness to and end.
