Construction starts in New York City's public works sector rose a whopping 82% to $4.3 billion last year compared with 2012, due largely to the start of initial contracts on three major metro bridge projects—the Goethals, Bayonne and Verrazano-Narrows spans, according to a New York Building Congress (NYBC) study. This sector along with the residential market were major drivers of the city's total activity, which grew 11% to $18.8 billion, according to the study, which is based on Dodge data from McGraw Hill Construction, ENR New York's parent.

Residential construction reached $6.3 billion, a 17% increase over the prior year. Apart from the three bridge projects, the top-10 project starts by value in the city were dominated by Manhattan residential projects, the study says.

Starts in the non-residential sector, however, dove 10% to $8.3 billion, according to the study, which used data on all starts between 2009 and 2013. The data included new projects as well as alterations and renovations to existing structures, and it reflects the total estimated value of each initiated project through the entire period of construction.

Richard Anderson, NYBC president, said in a statement that the bridge project starts bode well in the short term for the construction industry but that "the entire region stands to benefit for decades to come from these critical public works that will increase capacity and improve the efficiency of a major regional artery for the movement of goods and people."

Other public sector construction last year includes the initiation of several mass transit projects, worth more than $1 billion, the study shows. These include the Second Avenue Subway’s 72^nd Street Station; new East Side Access tunnels under Grand Central Terminal; modernization of interlockings on the Metropolitan Transportation Authority's Queens Boulevard line; and a box tunnel under Hudson Yards that will serve as the shell for a future Amtrak tunnel.