sentences:  New centres were created, and modern sports facilities were built in the Olympic zones of Montjuïc, Diagonal, and Vall d'Hebron; hotels were also refurbished and new ones built.The construction of ring roads around the city helped to reduce traffic density, and El Prat airport was modernized and expanded with the opening of two new terminals.The "Oxford Olympics Study" estimates the direct costs of the Barcelona 1992 Summer Olympics to be US$9.7 billion (expressed in 2015 U.S. dollars) with a cost overrun of 266%.