U.S. Transportation Secretary Sean Duffy faced bipartisan grilling Wednesday questioning the slow pace of his department’s release of funding for already-approved infrastructure grants, as well as the reduction of Department of Transportation personnel to approve them.

A leading Manhattan congressman who has taken the subway for years and the transportation secretary, who frequently criticizes the system, clashed over how dangerous it is at a House hearing in Washington.

The lawsuit before McConnell, who was appointed by President Barack Obama, which was filed after Duffy on April 24 notified states they could lose transportation funding if they do not cooperate ...