Standard&Poor's Ratings Services has affirmed its 'BBB+' underlying rating on Mid Bay Bridge Authority, Fla.'s senior-lien revenue bonds outstanding. At the same time, Standard&Poor's affirmed its 'BBB-' rating on the series 2011A and 2011B springing-lien revenue bonds. The outlook is stable. In our opinion, specific credit weaknesses include: An expected substantial increase in senior debt service in 2016, when the springing-lien bonds convert to senior-lien; The single-asset nature of a relatively small revenue stream (instead of a system of toll facilities); and Fluctuating traffic trends and a local economy that depends on the tourism industry. We believe offsetting credit strengths include: The Florida Department of Transportation's (FDOT) commitment to pay annual bridge operating and maintenance (O&M)