Digital Billboard

Washington County is considering additional restrictions on digital billboards in response to concerns over driver safety and light pollution.

(AP file photo)

Washington County is considering additional regulations on digital billboards in response to concerns such signs could endanger drivers and cause light pollution.

As soon as next week, commissioners could vote on an ordinance that would require advertisements to remain on the screen for at least 10 seconds -- two seconds longer than state law requires -- and limit billboard brightness to meet specific dark sky guidelines.

Field studies have shown that drivers look at digital billboards longer and more often than standard billboards. A 2012 study by the U.S. Department of Transportation determined that 63 percent of drivers looked at electronic billboards, compared with 37 percent for standard billboards.

Even so, the study did not conclude that digital billboards were enough of a distraction to increase driving risks.

In 2011, state lawmakers defined digital billboards as signs with rotating images no more than once every eight seconds that don't "create the appearance of movement." Since then, only a handful have sprung up in Washington County, and no accidents have been directly attributed to their presence.

Regarding light pollution, commissioners said Tuesday they were skeptical about imposing brightness requirements exclusively for digital billboards, and might defer voting on the issue until next year to do more research.

The county hasn't formally adopted any sort of dark sky standards.

"There was some confusion about what dark sky requirements mean," Washington County Chairman Andy Duyck said during Tuesday's board meeting. "This board has not adopted a dark sky policy."

Duyck also questioned whether standard billboards illuminated with spotlights at night actually cause more light pollution than digital billboards.

According to the Pacific Northwest chapter of the International Dark Sky Association, light pollution in the metro area is between 900 and 2700 percent brighter than celestial light — enough to obscure the Milky Way from view most nights.

-- Ian K. Kullgren