There may be times when you -- as a project manager -- are overwhelmed with the tasks of personally following up on issues and need some help, but this doesn't necessarily justify creating a new position or expanding the hierarchy to include a Program Manager who coordinates a team of project managers, as the extra workload may just be temporary.
Solution to Feeling Overwhelmed - Self-Organizing Teams:
I've worked in places where teams were self-organizing. In one case, I needed to train personnel on how to use software that we had recently developed and released as a private beta. The supervisors of the users were assigned the tasks of conducting the training, but all my time became consumed by answering questions and communicating with the 8 people handling the training.
I held a meeting and explained that I needed some help coordinating the training; I asked if one of the supervisors had extra time to help communicate issues and questions to me and relay the information back to the team. One person volunteered.
This supervisor took a lot of weight off of my shoulders. She picked my brain and learned everything she could about the software so that, when problems or questions were encountered, she could step in and help.
She also proactively asked the other supervisors questions about how the training was going and helped make sure that we were meeting our goals. Instead of having to follow up with each supervisor individually, I effectively delegated the task of making training a success by eliciting a highly-motivated volunteer.
When the training was completed and the software was released to public beta, the self-organizing team naturally dissolved.
In my experience, self-organizing teams can be unofficially formed and unofficially dissolved, and tend to consist of volunteers who not only have a strong interest in the project, but also they have a specific set of skills that make them a great fit for the point of contact/liaison.
Here are Some Helpful Tips on Self-Organizing Teams and How They Compare to Command and Control.