Update 12:30 p.m.: A hacker is responsible for the messages that appeared Monday morning on a portable work zone sign on Hunter Mill Road, said Virginia Department Of Transportation Spokeswoman Jennifer McCord.

"With the portable signs on site, it is sometimes possible to break into the locked control box and “hack” the sign," McCord said. "At the Hunter Mill bridge work, crews will be doing some more work over the next few weeks, but the sign will likely be removed and replaced as needed."

Unlike the overhead signs on interstates – which are protected and controlled remotely from VDOT's traffic operations center in Fairfax – many portable signs are controlled on site, McCord said. 

The sign in the work zone leading up to the bridge was a contractor sign, McCord said. All signs were operating normally by the time crews arrived on scene just before noon this morning.

"We have had a handful of reports of this type with portable message signs over the years, and it is, of course, tampering with state property," McCord said.

Update 10:20 a.m.: VDOT Spokeswoman Jennifer McCord says the department is looking into the incident.

Original: Commuters traveling on Hunter Mill Road toward the Dulles Toll Road on Monday morning found some unusual road advisories.

The large electronic, portable road sign just past Lawyers Road — placed there last week to alert drivers of lane closures on the Difficult Run Bridge — instead rotated between messages advising drivers to "please use condom," and warning, "alien spotted."

Reader Louise Foreman passed the sign just past 6 a.m. on the way to Dulles Airport. 

"That was a change from the usual detour or road closure message you usually see," she wrote in an email. "Certainly woke us up!"

Reader and blogger Cherie Lejeune also saw the sign around 7:45 a.m., she wrote in an email.

The Virginia Department of Transportation, who is managing the bridge project, did not immediately return calls for comment.