If you are using activeCollab 0.7.1 (free, open source version), there is no time tracking available. In activeCollab Corporate (current version is 1.1.4) there is time tracking module available.
I think Active collab should develop a project time tracking module in open source version through which one would be easily able to track the time spent on specific project.
I believe the entire point of open source is that you can make enhancements that you need. If you have the resources, you should go ahead and build this for aC 0.7.1. I am sure activeCollab team will put a note about it here so others who want it, can use it too.
On the other hand, activeCollab corporate already has extensive time tracking features - including project level time tracking. And it may be cheaper to buy the corporate version than to develop such a module from scratch.
I am new to Active collab .Is there any ption to track each employee work time in a particular project?