Most carriers require passengers to arrive at the station 15-20 minutes before departure and are authorized to re-sell your seat if you have not checked in 5-15 minutes before departure. (Actual times will vary by carrier).
If you missed your bus or train and you would like to catch the next trip out, it is important you contact your carrier as soon as possible to check what options are available to you. You can also head over to the ticket office and ask an agent on staff if available.
Unfortunately, most of the time a missed trip will usually result in a voided non-refundable ticket and you will have to purchase a new ticket for a later bus.
Some carriers, like these, may allow you to board a later bus as a standby passenger:
Eastern Bus - Valid only same day, subject to availability
Best Bus - Valid only same day, subject to availability
Wanderu is a third-party ground carrier search platform and has no authority on refunds, cancellations or changes in itinerary. All reservations and transactions are done directly with the bus/train company you choose to travel with and will be subject to the carrier's terms and conditions.