There weren't any very difficult questions. If you have been through the interview process you will more than likely be able to get through the phone interview to the 1:1. Then it seems like it's whether they think you can do the job or not.
Being shy/timid/quiet will not get you this position. They are looking for people with confidence and the ability to lead a field crew (i.e. be around people who speak their mind regardless of how it makes you feel)