Filthy! A Montana Rail Link helper set led by brand-new EMD SD70ACe No. 4305 coasts through Austin, Montana, heading eastbound back to Helena after helping a train up Mullan Pass. The soot and filth coating the east end of the set is thanks to the tight confines of Mullan Tunnel at the top of the pass. An accumulation of grime like this happens fast—this is one trip up the mountain! MRL enlarged the clearances of Mullan Tunnel in 2009, making it five feet taller and three feet wider, as well as about 400 feet shorter. This gave the helper units more space to “breathe,” especially for the locomotives on the east end of the set. When these locomotives were new, MRL had them washed nearly every day to rid them of the quickly accumulating blanket of grime while in helper service.