The problems became so extensive that federal authorities cut the number of flights allowed in and out of the airport to 28 arrivals and 28 departures per hour.

RTD has very few extra bus operators right now, Nicholson said, which makes responding to service changes a challenge.

Transportation Secretary Sean Duffy vowed Wednesday that improvements should significantly ease delays and safety concerns at troubled Newark Liberty Airport by the Fourth of July holiday.

Duffy reiterated calls for Congress to provide tens of billions of dollars to build a new air traffic control system.