Too shy to say hi to people I barely know. Normal? Help?

[Sunshine on a Cloudy Day]

People I barely know, such as mere classmates.

I usually just walk by them in the hall unless they say hi to me first because I'm too shy.
They may or may not see me themselves.

Now don't get me wrong. I'm an upper freshmen college student with lots of friends, but those were mostly from highly interactive classes in which everyone got to know each other and my school's online Facebook groups and my People You May Know page on Facebook.

Is this normal?
Do you face this too?
How can I overcome this?

[XxGirlxX]

I dont say hi too anyone they can talk to me if they want, I'm not forced to talk to them