A portion of the Des Moines freeway had to be closed today as the pavement buckled in the heat. Dena Grey-Fisher of the Iowa Department of Transportation says two of the three lanes in a four-block area were closed.Grey-Fisher says with the high humidity, moisture’s getting in the pavement cracks and that causes the blow ups. She says it’s a common occurrence during these weather conditions. Grey-Fisher says crews should have the spot fixed before rush hour begins in Des Moines this afternoon.