TCL commands to determine routing congestion

I'm trying to find relevant TCL commands to determine routing congestion as shown in the ChipPlanner.

Attached are a couple of screenshots to illustrate what I'm asking.

Also:

- What's the definition of routing elements. I understand there are different types of routing resources. So why it's bundled into a single number.

- Where is the routing element count coming from. Is it across some XY cut ?

Thanks,

Evgeni