How do I get the path to my apache server root?

[JonBlockBoston]

I need the path to the apache server root.

I do not need the path to the document root.

For example, my server root for one of my servers is:

/usr/local/apache2/

Is there a PHP function that will specifically give me the server root?

Thank you,
Jon

[NogDog]

I am not aware of any such function, variable, or constant built in to PHP.

[Weedpacket]

Could it perhaps be determined from a combination of $_SERVER's SCRIPT_NAME and SCRIPT_FILENAME elements?