The Chicago Department of Aviation (CDA) has opened a $516m new runway and an air traffic control (ATC) tower at O'Hare International Airport.
Proposed under the 2008 O'Hare Modernization Program (OMP), construction work began in 2011.
Therunway 10R-28L is the airport's fifth east-west parallel runway.
Located in south airfield, the 7,500ft-long and 150ft-wide runway will be used primarily for arrivals.
The plan includes a 7,500ft-long east-west parallel taxiway located at the north of the runway and a 2,000ft-long connecting taxiway to the south.
The $41m South Air Traffic Control Tower (SATCT) has been built to manage aircraft operations at the new runway.
The 218ft-tall tower with 13 levels is built on a 10,000ft² base building and includes a vegetated green roof and a geothermal energy system.
CDA commissioner Ginger S Evans said: "Modernising our airfield and improving capacity at the world's busiest airport is critical to addressing many important challenges such as reducing delays, mitigating noise and improving the customer experience."
The new runway is expected to support east flow operations by increasing throughput and reducing delays under all weather conditions.
CDA estimates that the new runway will bring about 24% increase in airport arrival rates amounting to 114 flights per hour compared with 92 hourly flights previously, along with about 25% increases in airport departure rates with 110 flights per hour when compared to 88 flights per hour earlier.
In August, the airport shut one of its diagonal runways amid opposition from lawmakers and residents. The second diagonal runway at the airport is expected to be shut by 2020.
Image: The runway 10R-28L is the fifth east-west parallel runway at the airport. Photo: courtesy of O'Hare International Airport.