NEW YORK - S&P Global Ratings has assigned its 'AA-' rating to the Triborough Bridge and Tunnel Authority (TBTA), N.Y.'s pro forma $265 million series 2017A general revenue bonds and $400 million series 2017B general revenue refunding bonds. The outlook is stable. The series 2017A bonds are being issued to finance bridge and tunnel projects. The series 2017B refunding bonds, depending on market conditions, will be issued to refinance certain TBTA general revenue bonds outstanding for debt service savings without extending maturities. S&P Global Ratings also affirmed its 'AA-' and 'A+' underlying ratings (SPURs), with a stable outlook, on the authority's general revenue bonds and subordinate revenue bonds outstanding. In addition, S&P Global Ratings affirmed its 'AAA/A-1+' ratings and SPUR on the TBTA's general revenue variable-rate bonds, series 2001B; and its 'AA+/A-1' ratings and SPUR on the authority's general revenue variable-rate bonds, series 2001C, 2002F, and 2005B-3. These ratings reflect our application of the low correlation joint criteria based on our 'AA-' SPUR on the authority and the ratings on the series 2001B letter of credit (LOC) provider, State Street Bank and Trust Co. Ltd.; the ratings on the series 2001C and 2005B-3 LOC provider, Bank of Tokyo-Mitsubishi; and the ratings on the series 2002F LOC provider, Landesbank Hessen-Thueringen Girozentrale. The short-term component of the ratings reflects solely the short-term counterparty rating of the corresponding LOC provider for the bonds. The outlook on the long-term ratings is stable. Finally, S&P Global Ratings affirmed its 'AA+/A-1' ratings and 'A+' SPUR on the TBTA's subordinate revenue refunding bonds, subseries 2013D-2a and 2013D-2b. These ratings reflect our application of the low correlation joint criteria based on our 'A+' SPUR on the authority and the ratings on the subseries 2013D-2a and 2013D-2b LOC provider, Bank of America N.A. The rating's short-term component reflects solely the short-term counterparty rating on the LOC provider. The outlook on the long-term ratings is stable. The ratings on the bonds reflect our view of the TBTA's consistently strong historical financial performance and service essentiality, and our expectation that the authority will maintain combined debt service coverage (DSC) at levels adequate for the rating. More specific credit strengths, in our opinion, include the following: • A mature seven-bridge and two-tunnel system we consider essential--providing critical links to the congested New York City area—and that faces limited traffic diversion from capacity constrained competing facilities that have ongoing construction. • Traffic levels that have been generally stable, with traffic increasing 0.4% on average per year from 2010-2015 despite toll increases in 2009, 2010, 2013, and 2015, resulting in an 27.7% increase in toll revenue from 2010-2015. • A proven ability to raise tolls as needed without materially affecting long-term traffic patterns, despite above-average toll rates. • Consistently strong combined DSC that we expect will remain strong based on current estimates. We believe the TBTA's high debt load, additional debt needs, and mandatory fund transfers of 90% of the authority's surplus revenue to the Metropolitan Transportation Authority somewhat offset these credit strengths. "The stable outlook reflects our assessment of the high level and relatively price inelastic demand for authority facilities during our two-year outlook period, resulting in the TBTA's flexibility to raise tolls as needed," said S&P Global Ratings credit analyst Joseph Pezzimenti. The outlook also reflects our expectation that the TBTA will maintain a combined DSC of no less than 1.5x. It is unlikely we will raise the ratings in the next two years due to the TBTA's additional debt plans and conversion to open road tolling. We could lower the rating if coverage falls below the combined DSC threshold stated above or if management uses additional authority debt to finance mass transit or commuter projects.