LOS ANGELES - At first glance, a digital billboard alongside the road looks very much like a conventional billboard. But give it a second look and the difference is obvious.
These billboards use the latest technology in outdoor advertising to cycle through images every four to 10 seconds, displaying multiple messages from one or more advertisers on one sign.
Two studies found that they are not traffic hazards, and the Federal Highway Administration (FHWA) has concluded they don't violate federal law. But not everyone favors them, and the studies themselves have been challenged. Opponents of the high-tech billboards say the signs are dangerous distractions, as well as "visual clutter" that detracts from the natural beauty of America's landscape.
Digital billboards are still a rare and recent addition to the nation's roads. They account for about 700 of an estimated 450,000 billboards across the United States, according to the Outdoor Advertising Association of America (OAAA), an industry trade group. They're made of tiny LEDs - light emitting diodes - and can cost upwards of $250,000.
So far, they are legal in 38 states and more states are grappling with whether to embrace them after a recent FHWA memo said the signs were not violating the law along interstate and federally financed roadways.
Advocates of digital billboards say they can help law enforcement. Their messages have been overridden to show Amber Alerts for missing children, "wanted" posters for criminal suspects and other important messages. Fifteen minutes after the deadly interstate bridge collapse in Minneapolis on Aug. 1, for example, digital billboards in the area directed drivers away from the disaster.
Five states - Maryland, Massachusetts, Oregon, Texas and Washington - allow only a more rudimentary changeable billboard technology called Tri-action, which rotates messages mechanically. North Dakota, New Hampshire and Wyoming allow only traditional poster-and-glue billboards, while four other states - Alaska, Hawaii, Maine and Vermont - ban all billboards.
Texas is inviting public comment until Dec. 6 on proposed rule changes that would allow digital billboards only in municipalities that want them and agree to follow state guidelines, said Randall Dillard, spokesman for the Texas Department of Transportation .
States and the federal government work closely to achieve uniformity in all aspects of highway travel, including pavement markings, lane width and advertising. Several states had asked the FHWA, a division of the U.S. Department of Transportation, whether the roadside digital signs met federal requirements, FHWA spokesman Doug Hecox said.
In a memo issued Sept. 25, the FHWA said digital billboards conform to the Highway Beautification Act of 1965, which states are obliged to enforce. The law prohibits flashing, intermittent or moving lights on billboards, which the FHWA interpreted as different from the digital signs in which images are fixed for several seconds. The memo extended to the new technology the same permission that was given in 1996 to the Tri-action billboards.
"We simply allowed an existing permissibility to be extended to these newer signs because they're so similar to the ones that were already allowed. For us to ban one and not the other ... would have been very inconsistent," Hecox said.
He stressed, however, that states have the final word: "For us to suggest that some signs or some types of technologies are OK doesn't mean that everybody can just go out and put these things up. It's up to the states. The states still have the right to refuse, if they want."
But one advocacy group thinks the FHWA's tacit approval of digital billboards is a flagrant violation of the Highway Beautification Act - especially the law's prohibition of "intermittent" lights on billboards.
"Everyone knows what (intermittent) means. It means something that happens repeatedly over and over and over again. … You couldn't find a device that is more intermittent than a digital billboard," said Kevin Fry, president of Scenic America , a Washington, D.C.-based group that seeks to limit outdoor advertising. Expressing a view shared by other critics, Fry called the signs "visual clutter" and aesthetically unappealing.
Advocates and critics of digital billboards disagree most over whether the signs pose a danger by distracting drivers.
Bryan Parker, executive vice president for real estate and public affairs at Clear Channel Outdoor, which calls itself the world's largest outdoor advertising company, pointed to two studies that concluded digital billboards present no safety hazard. A Virginia Tech Transportation Institute report in March 2007 found that digital billboards had no effect on driver behavior. Consulting-engineering firm Tantala Associates found no link between digital billboards and crashes.
But a peer review of those studies, commissioned by the Maryland State Highway Administration, placed serious doubt on their findings. It said the reports' methodologies were flawed and "ordinance or code changes based on their findings is ill-advised." The reports are biased, it said, because they were industry-sponsored by the OAAA's foundation. The advertising trade group confirmed its connection to the reports.
Maryland, which has few billboards dotting its landscape, contracted with Jerry Wachtel, a noted human factors psychologist, to examine the studies, said Tom Hicks, director of the state transportation department's office of traffic and safety.
Hicks said Maryland won't approve the new billboards until they are proven safe, and the peer review is "a reference to use as we dive into this situation."
"Now you have three reports out there. The more data the better," he said.
Even though the FHWA already approved the signs, it is in the planning stages of its own study on their safety, Hecox said. Results should be made public by 2009. Hicks, Fry and Wachtel all said they were baffled by the FHWA's decision to issue its memo before conducting its own study.
Clear Channel's Parker said he expects the safety of digital billboards will be verified in future studies. Clear Channel already has these billboards stationed along freeways in major metropolitan areas such as Cleveland , Philadelphia and Chicago, at locations where conventional billboards were converted for digital use, he said.
"From our studies that we've seen - the Virginia Tech study and the accident data from Tantala Associates - we have no reason to believe that the findings would be any different by any other group. We're very confident that the results they've come up with would be replicated in any other study," Parker said.
As states take stock of existing data and public opinion, experts will continue to weigh in on the new technology. At the January 2008 meeting in Washington, D.C., of the Transportation Research Board , a division of the nonprofit National Research Council, Wachtel, the author of the Maryland study, is scheduled to conduct a day-long workshop titled: "Digital Billboards on the Highway: A Bright Future?"