Program Room - How the Runway widget actually functions

The Runway widget provides any given Program a point in time visual representation of the relative health of the backlog of work. 

Consider how a Scrum/Kanban Team needs to have a healthy backlog of work that will allow them to progress through 4-8 Sprints, if they have too little (1 -3 Sprints) they may quickly reach a point where they don't have enough work to fill their sprints (Scrum) or keep continuous flow moving (Kanban); if they have too much work 9-24 Sprints they will be less effective due to the nature of attempting to maintain such a lengthy backlog. 

The very same is true for a Program, however the Program deals in a larger suite of work items than stories and needs a view into their work from Epics down to Stories with an appropriate timebox to understand that work.