Is it possible to avoid running 2 parallel builds of same project?

Hello,

I have a project with trigger which triggers build at every hour (I do not want run build at every source checkin). But sometimes I want to run build immediately at some source checkin so I trigger build manually (build takes some time, approx. 30 min). In this case if trigger happens the teamcity starts an another build of this project, which I want to avoid without always disabling/enabling trigger. Is it possible?

Thanks

Regards, Gabriel