Report: Explosion interrupts New York City subway construction

“We were doing a controlled blast when clearly something went awry and an explosion was felt at street level,” New York Metropolitan Transportation Authority (MTA) spokesman Adam Lisberg told the paper. 

Plans have existed for the proposed Second Avenue Subway in New York since the 1920s, first as an elevated railway and then as an underground line.

The latest incarnation of the project has been under construction since 2007. It is one of the largest "heavy rail," or fixed electric railway projects that is currently being built in the United States, along with an extension of Washington, D.C.'s Metrorail to Dulles International Airport.