MONTGOMERY COUNTY, Md. — Camouflaged behind a portable toilet on the shoulder of Interstate 270, a state-owned mobile unit deployed to detect speeders is snapping away as unsuspecting drivers go whizzing by.

The unit has been deployed sporadically over the past few weeks on the shoulder of the southbound lanes of the interstate right before the construction zone at the future Watkins Mill Road interchange with I-270.

RELATED: Confusion, contradictions plague DC speed camera warning signs

There are new signs reminding drivers of the 55 miles per hour speed limit and new signs leading up to the construction zone warning about the presence of speed cameras.

The Maryland Department of Transportation's State Highway Administration is responsible for the mobile speed detection unit. Media relations manager Shantee Felix confirmed to WUSA9 all drivers caught speeding in this area have received warnings.

In an email exchange with WUSA9, Felix said the warning phase will end on Wednesday, Jan. 23 and beginning the next day, drivers will be issued citations if they exceed the posted speed limit by 12 miles per hour or more.

A review of the SHA's website which reveals the location of all operating speed cameras indicates this is the only state-run speed camera in operation in Montgomery County.

An SHA speed camera in place on I-270 for 17 months between 2011 and 2012 netted more than 22,000 speeding citations.