The Turner Corp., the nation’s leading general builder, announced that construction costs in 2003’s second quarter are estimated to remain flat from the first quarter. The stagnant costs are primarily due to the commercial construction market’s cap on prices, as well as increasing insurance, bonding and labor costs, said Karl F. Almstead, Turner’s vice president responsible for the Turner Building Cost Index. This is the third quarter in a row that costs have been predicted to remain level.