Television and newspapers sit at the top of many agency marketing plans, while outdoor advertising stays at the bottom. The reason for this is that it’s difficult to account for who views a billboard, so there is no way of consistently determining the effectiveness of outdoor advertising. As a result, agencies do not consider the medium and allocate their money elsewhere. To change this situation, one needs to create new credible audience measurements for the outdoor marketing industry. Here we propose a new way of performing audience measurements that combines mobile phone location estimations with information freely available on the Internet. We show that it is possible to estimate the number of people who drive or walk by a given area i...