Lack of advertising affecting business growth

I've been working at a Dunkin' Donuts for over a year, and my current position and relationships with other manager allows me to get inside information on how business at other locations is going. Earlier this year the owner of the franchisees in North Alabama opened his fifth location, in Athens. This store is in a great location less than a mile from the interstate with easy access, but business there is not where anyone expected it to be. After talking with employees of that location, customers that drive from Athens to my location in Madison, and even the owner I've come to realize very few people know the store is there. The location doesn't have any billboards on the interstate and only a small sign in front of the store. I feel the lack of advertising is having a negative effect on business. If the store had a billboard north and south of the exit, a larger sign out in front of the building, and some advertising in the community I feel sales would at least double. Their target audience needs to be travelers on the interstate, especially during summer months and holidays when traffic is high from people heading to and from their vacations.