Summary: This testimony discusses challenges associated with building new runways and with ensuring that existing runways are properly maintained. Recent flight delays and cancellations as well as significant media attention have heightened public concern about the need to increase the capacity of the National Airspace System. According to the Federal Aviation Administration (FAA), 24 of the nation's 50 busiest commercial service airports have proposed, planned, or begun construction on new runways and runway extensions at an estimated cost of $6.5 billion. Airports and FAA face challenges in building new runways and in determining at what point runway pavement conditions warrant repair in order for existing runways to be maintained in the most cost-effective manner. The federal government and the aviation industry are involved in several efforts to balance airports' growth with environmental concerns and to address runway maintenance in a cost-effective way. Additional actions would help minimize some delays associated with adding capacity and problems with preserving existing capacity.