Hello all, to get I-HT what I've done is I have all my I-D and I-M in a couple other cities, and i've created enough of them to exhaust the demand for them. Once I've done that in yet another city I get everyone well educated 180+ Eq and raise the land value such that I have alot of R-$$ and R-$$$ and I then zone alot of industrial next to them (where the land value is high) in the same city and normally they develop right away into I-HT. It seems that you still need a really large population because I-M are the most filled jobs before the demand sorta spills over to I-HT. I do this because I don't really like modifying the industry's tax structures and also because many R-$$ and R-$$$ still work at I-D and I-M, which i'm guessing as managers and the such.