This has probably been a dirty little secret in the advertising world for some time now. Outdoor advertisers love traffic congestion and back-ups. Such traffic problems mean prolonged exposure to the billboards and other ads along the highways and byways as people commute back and forth. That means, as old-media as outdoor advertising might seem, it still has tremendous value and indeed revenue has grown consistently over the last five or six years.

Here's the problem I always had with outdoor ads, though: How do you measure success? If it's just eyeballs then that's fine. Have fun with that. But is there a real way to draw a line between those eyeballs and sales? If you run a billboard in Oak Park (just outside Chicago) do you then figure X% of sales in Chicago were because of that ad? And if so, do you realize that's an arbitrary number? I'm seriously asking, where's the sales numbers accountibility when it comes to outdoor advertising? Seems to me that because of the fluidity of traffic it's the least measurable since where the person sees an ad and any subsequent purchase can be so far apart that measurement is almost impossible.