What is the preposition category of "along"?

Solution 1:

I fear your categorization is based on unsound foundations, but let's just look at along:

The signs were on buildings along Main Street.

Passive.

He traveled along roads that were long and painted purple.

Active.

Assuming that I correctly understand how you're categorizing prepositions, then it's a preposition that can be in either state.

Solution 2:

Along is a preposition of place and direction. Active and passive might work for understanding and visualizing the word but not as standard grammar categories for prepositions.