Work Demands I Arrive 30 Minutes Early Without Clocking In

I work on a construction site, recently rules were made that force us to park off-site and take a shuttle bus to our work site, this means that I must arrive for this shuttle bus a full 30 minutes earlier than I would normally arrive at work, we are required to take this bus to the work site, there are no other parking options, this is in the U.S.A.

Is taking this shuttle bus a work responsibility? I feel that I should be getting paid for this as I am required to show up an entire 30 minutes earlier to greet this bus as per work rules, however my employers are demanding that we do not clock in until the same time we used to clock in, 30 minutes after I am actually required by them to be there, what should I do? Am I legally in the right? Is there anything to be done about this?

I apologize if my post lacks any necessary context, it's my first time posting here, any and all advice is appreciated.

Slight addendum: this bus only takes us halfway so we have to walk the rest which is a mile hike for no discernable reason