Following up on recent discussion of Metro’s lighting, it’s important to understand how much the surface that’s to be illuminated matters in Metro’s indirect lighting scheme.  Earlier, I noted that Metro is currently going though a process of deep-cleaning several stations in the system – replacing light bulbs, cleaning the walls, etc.   The Washington Post had a great article in March on the process for each station:

Blasts of steam from the hoses they carry scour dust from train brakes and concrete away from the panels. Sensitive equipment, including pylons on the platform, is protected from the spray, but the station is warm and misty.

Once the station is cleaned, the crew will re-bronze rails, paint kiosks and repair tile, among other tasks.

A station gets enhanced about every three and a half years. The crews do two dozen stations a year, focusing on indoor stations during cold weather.

“We’ve got it down to a science,” says Tom Morrison, Metro’s superintendent of contract maintenance and station enhancement. The job begins with a lot of prep work after the Red Line shuts down at midnight. Power to the third rail must be cut and station equipment protected.

The crew must wrap up about 4 a.m. The workers will need to be gone, the equipment stored at the end of the platform or hauled away and the station dry by the time passengers arrive and trains start running at 5 a.m.

It’s not easy adjusting to the schedule — five overnights in a station and two off days trying to have a real life — but workers at least get a direct view of what they’ve accomplished. “We can see the before and after,” says craft supervisor Andre Jordan.

Steam cleaning the walls makes a huge difference.  This process is currently underway at my nearest station, Potomac Avenue.  Dr. Gridlock noted earlier in the year each of the stations scheduled for a “station enhancement,” as Metro describes the process:

Major Enhancements: Dunn Loring, East Falls Church, Eisenhower Avenue, Forest Glen, Medical Center, Potomac Avenue, Twinbrook, Wheaton, White Flint, U Street, Vienna, West Falls Church.

Mini Enhancements: Ballston, Bethesda, Brookland, Court House, Foggy Bottom, Franconia-Springfield, Friendship Heights, Rockville, Shady Grove, Smithsonian, Virginia Square, Woodley Park.

The majors and the minis involve different types of work. A major takes about three months. A mini takes about 25 percent less time. I watched some of the overnight work for a “major” at Cleveland Park. During the hours the station was closed, crews on lifts power washed the station’s concrete ceiling and walls. I could see the before and after, and the difference was remarkable as they removed the tunnel dust that gathers in the station.

To get an idea of how much dirt and grime accumulates over the years, have a look at the process in action:

Potomac Ave deep cleaning, Dec 2009

Metro initially ‘painted’ several stations in order to lighten them up a bit – but the painted surfaces don’t quite have the same warm feeling that the original concrete does.  They also show the dirt and grime more than their concrete counterparts.

Compare, side by side, the clean side of the station to the uncleaned one:

It’s not just the grime accumulating on the lower portions of the vault – there’s a huge difference in the dirt on the bottom edges of the coffers – that’s not just shadow (despite my crappy camera).