traveled all over this country, Alaska, and Canada, and a lot of bridges and tunnels, and have never 'turned off' the propane, including thru the long Chesapeake bay bridge travels...
since all of our propane devices are electronic spark, and not active 'pilot lights', then they ARE off all the time.
the problem one of the authorities not wanting a propane leak to be susceptible to a spark while in a tunnel, specifically if you would have to come to a stop due to a traffic jam or accident... where vehicle motors are running, or worse, someone is smoking nearby.
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