Many companies have tried to take advantage of big, blank semi trailers as rolling billboards. Until now, however, getting buyers has been difficult because there was no way to tell how many people saw the ads. One company now says it has the answer.

The Traffic Audit Bureau says it has a method that will confirm the number of people exposed to an advertiser's message on the side of a truck.
The methodology, which requires the use of a Global Positioning System tracking device, uses a model based on data from the Federal Highway Administration's Highway Performance and Monitoring System. The GPS data on a truck's movements is entered into the model via custom software to generate an estimate of the number of impressions visible to the occupants of cars passing in both directions as the truck travels its route.
The truck advertising operator then is able to provide its advertising clients with a Truck Advertising Project Statement detailing the total gross impressions during a completed campaign and the average daily effective circulation per truck, for the advertiser's program.
In addition, the TAB will perform an annual on-site audit with each participating fleet and truck advertising operator to substantiate that they are using the methodology and software correctly. Upon successful completion of the audit, the TAB will issue an annual Truck Advertising Audit Statement.
A trial of the new system was performed in Chicago with trucks carrying an advertisement for Seiko watches from Nov. 1 to Dec. 10. Three commercial trailers, operated by the Fleet Advertising Media Group, originated each day from South Kedzie Avenue in Chicago and traveled heavily on the interstate highway system, making deliveries to multiple locations each day.
The TAB Truck Advertising Audit Methodology for the Seiko program trial yielded preliminary results that indicated its truck-side advertisement daily effective circulation reached an estimated 40,585 commuters each day per truck. In comparison, the average billboard in Chicago measuring 14 feet by 48 feet attains about 48,000 daily effective circulation, according to the TAB.