The second-busiest commercial air carrier at Harry Reid Interational Airport is expanding service to and from Austin, Texas. Atlanta-based Delta Air Lines will double the number of daily flights to and from the Texas capital to two beginning in the fall. Demand for trips to Austin, which calls itself “The Live Music Capital of the World” and features multiple music festivals all year, including March’s SWSX multimedia event, is growing, according to Delta. The airline said it expects both markets will benefit from the service expansion. Delta competes on the route with market leader Southwest Airlines, Frontier Airlines and Allegiant Air. The new demand was not the result of the May 2 shutdown by Spirit Airlines, which didn’t serve the market from Las Vegas. Most Delta flights from Las Vegas are to its hub cities of Salt Lake City, Minneapolis, Detroit, Seattle, Boston and New York’s John F. Kennedy International Airport.…