If you are on the bus prior to entering the park, you're fine. If you catch the bus inside the park all you need is entry fee to the park. The " going to the sun road" pass is the difficult one. Bus pass covers that.
If you have reservations for anything along the GTS road, that reservation is your entry ticket for GTS for that day only. A "general" park pass is required for entrance into the park, regardless.
You need to buy the entrance pass to park. But the GTS pass is not needed if u have and reservation inside GTS road
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