If you drive along any of the interstate routes in Cleveland, you might see a billboard change before your very eyes. No, your eyes aren't playing tricks on you. Clear Channel Outdoor, San Antonio, is testing seven LED billboards that change their message every 8 sec in a pilot project throughout the Cleveland area. The boards give drivers the chance to see a variety of messages from one sign.

The prototype billboards were built for Clear Channel by Daktronics Inc. in Brookings, S.D. Daktronics is noted for its large-format electronic displays and scoreboards. It has installed more than 1,500 ProStar and ProAd systems since 1997. Derived from its ProStar line, the electronic billboards in Cleveland are the largest single display units built by Daktronics to date.

Each of the 14 48-ft billboards function as large video screens containing-449,280 daylight-visible full-color LEDs. The control system consists of a central Daktronics V-Net controller located at Daktronics headquarters in South Dakota with remote controllers in each display. The V-Net system is used to create, upload, display, schedule, and log the content shown on the seven boards.

Photocells mounted on each sign let the V-Net controllers track ambient light levels to control both LED brightness and gamma levels. Brightness, of course, is the intensity of light emitted by the LEDs while gamma controls the contrast between the lightest and darkest portion of the display. The result provides optimum viewing in conditions ranging from direct sunlight to moonless nights.

Daktronics Keyframe services group generates the billboard content during this pilot project. Initially, the board carried ads from many of Cleveland's nonprofit institutions such as the Animal Protective League and the Cleveland Zoo. Keyframe also provides technical and creative support for the networked system of billboards. Digital images created for the boards are downloaded remotely through high-speed Internet connections.

In the past, outdoor advertisers bought advertising by the amount of space the board occupied. The electronic billboards herald a change: advertisers now purchase time rather than space, similar to the economics of radio and TV. The billboards also provide near instantaneous response to critical messaging needs such as Amber Alerts, major storms, or other emergency situations.