I am thinking of making use of Chengdu Sightseeing Bus services for me visit.

However can you advise me on the interval of these bus services? Do they operate at the start of period or they operate at a fix interval.

I have 4 days in the city, and i am thinking of multiple place within the city plus the following that is outside the city:

Mt. Qingcheng & Dujiangyan Irrigation Project
Research Base of Giant Panda Breeding & Three-Star Piles Museum
Three-Star Piles Museum