Des Moines International Airport will install a third baggage screening system behind the scenes because growing passenger traffic is testing capacity, airport General Manager and Executive Director Kevin Foley said. The equipment will be behind the ticket window areas and out of sight of travelers, as the current system is. Foley said the baggage screens are one of the potential bottlenecks to keeping flights on time, and they are loaded with people’s bags.  It is unrelated to the TSA security area in the terminal. Foley said the project has been approved by federal officials but a timeline has not been set.