[mhays]

Grade separation is really important to both speed and reliability. I agree that it should be a priority.

The issue is how we fund things in the US. Since transit has to go to the voters on a per-phase/project basis, and voters are often selfish and shortsighted, they have see benefit to themselves for each project. The mileage will matter more to them than future proofing and operational simplicity.

Speaking for Seattle's experience (with some grade crossings, though not in the core), both speed and reliability have become issues. At least we don't have the issue of block-length limiting train length since our at-grade stations aren't in small-grid areas.