Passenger traffic at Des Moines International Airport was up 6.7 percent in September compared with the same month last year — double the initial projection. For the year, traffic is up 6.4 percent and has reached this level six years earlier than expected, airport chief Kevin Foley said. The strong growth has been fed in part by the airlines offering more seats and, in some cases, new destinations. That growth is beyond the level airport administrators have said would be needed to support a nearly half-billion-dollar plan to build a new terminal and to improve airport operations. The airport’s biggest carrier, American Airlines, gained 10.4 percent in passenger traffic in September. United Airlines gained 11.7 percent and Delta Air Lines 2.5 percent. September sent year-to-date passenger traffic to just over 2 million. The one-year record, set last year, is 2.58 million. If the September 2018  total of 217,902 passengers carried through the remaining three months of the year, this year’s total would be 2.7 million, a new record.