S&P Global Ratings assigned its 'AAA' rating and stable outlook to Ann Arbor, Mich.'s roughly $15 million series 2022 Michigan Transportation Fund (MTF) bonds and affirmed its 'AAA' rating, with a stable outlook, on the city's existing MTF debt. MTF revenue secures the bonds; to the extent pledged revenue is insufficient, the city's limited-tax general obligation (GO) pledge provides additional security. We rate the MTF bonds under our criteria, titled "Priority-Lien Tax Revenue Debt," published Oct. 22, 2018, on RatingsDirect, which factors in pledged revenue strength and stability and Ann Arbor's general credit quality. In accordance with our criteria, titled "Methodology: Rating Approach To Obligations With Multiple Revenue Streams," published Nov. 29, 2011, the rating reflects our view of the