When using 'outbound', always indicate you're leaving a point towards a different destination. The next outbound train departs in 10 minutes.
Pro Tip 2/3
Mention Origin
It's common to mention the starting point when talking about outbound travels. Her outbound journey from Chicago starts at noon.
Pro Tip 3/3
Different from Return
Don't confuse 'outbound' with 'return'. Outbound is when you leave; return is when you come back. His outbound flight was delayed, but his return flight was on time.