When I read this tweet from the CTA, I was definitely intrigued to investigate:
"A few new work photos posted: Sewer-cleaning train: http://ow.ly/98CNs (Perhaps not the most glamorous work, but it’s got to be done!)"
I was not disappointed. So I wanted to share the photos with you, plus CTA's explanation of the subway sewer-cleaning process:
These photos show recent work to clear sewers and drainage in the subway. This "sewer train" has special equipment with hoses and pumps on a trailer that is towed by a train of CTA passenger cars (these are special cars designated for "work service" and have specially configured motors that make it easy for them to tow heavy equipment, when needed).
CTA workers shown here use this equipment clear drains of material that could cause them to clog, and ensures that water that makes its way into the subway can be properly collected into the city's sewer system.
Work like this is done overnight to minimize the impact on passenger service. On many routes, maintenance that is done at track level is done during hours where trains aren't in operation, but in Chicago's subways, where service operates 24/7, regular passenger trains operate over a single track through the area to allow for this important, regular maintenance work to be done.
View the entire Flickr photo set of the sewer cleaning at the Chicago Red Line station.