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Thank you for riding with us today!
Literal
Today [topic-は] honorable-riding receive thank-you!
お乗りいただき is the お+masu-stem+いただく humble pattern: お乗り (honorific form of 乗る 'to ride/board') + いただき (humble form of もらう, 'to receive [the favor of]'). It's the keigo template for 'thank you for [verb]ing.' The exclamation mark and spoken delivery suggest a transit announcement — bus or train conductors deploy this warmly when greeting boarders or wrapping up a route.