It would be really cool. You wouldn't have to worry about getting an Ezpass and loading that up as long as you have some Bitcoins in your wallet
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Yeah, you only need to wait 10 minutes at the booth for the transaction to confirm
Most merchants (toll road likely included) can safely accept a 0/unconfirmed transaction for smaller amounts as it costs a lot to attempt a double spend attack and these attacks only have a positive EV with larger amounts as they do not always succeed.