Autorouter strategy: when a net can't route, tear out the blocking traces and re-route both. The cure for plateauing on congested boards.
How it looks
Drawing: a routing grid, not a part of CORE3588
A drawing on a routing grid. Faint dashes: where A was first routed (blocking B). Solid: after ripping A up, routing B, and rerouting A through the far gap.
How it works
Where it fits
Rip-up and reroute is the classic cure for a bad routing order on a crowded board. Freerouting uses it in passes.
Negotiated congestion is the gentler cousin: instead of tearing nets out, it lets them overlap and raises the price of crowded squares until they move.