We've followed the $10.8 billion East Side Access project, which will extend the Long Island Railroad from Queens to Grand Central, all year. But now that the tunnels have been blasted, new machines are arriving—and they're just as cool as the tunnel borers.

This month, crews are working on turning empty rock caverns into actual train tunnels, which involves installing insulation along the raw bedrock surfaces of the tunnels:

One photo in particular caught my eye, showing a cannon-like device spraying water into the cavern:

I asked the MTA's Kevin Ortiz what was going on here. He told me that, paradoxically, it's all part of the waterproofing process. That's a Dust Boss, an industrial water cannon that sprays mist to the air to control dust.

They're usually used at demolition sites to control the amount of dust flung into the sky. This one looks like the DB-100 [Update: DustBoss tells us it's actually a DB-60], the largest model ever built, which is recommended for large spaces like mines and quarries—and subway tunnels, too, apparently. It's actually a similar concept to the one proposed by a Chinese scientist to control smog in cities using huge sprinkler-like apparatuses.

"The device sprays a mist to take the dust down in the cavern while they are applying the Shotcrete in the caverns," says Ortiz. What's shotcrete? It's a concrete mixture that's applied using a pressurized hose; it'll help keep the tunnels clear of ground water leaking through the rock.

Go take a look at the full set on the MTA Flickr page—after all, this is the very last time humans eyes will get to look upon the raw bedrock that our trains will eventually run through. [MTA]