HQTA Methodology follow-up: enforce partial collinearity and check branching

[edasmalchi]

Research Task

Per ongoing discussion with stakeholders, build on #1230 to further improve dataset accuracy.

• While combining frequencies from multiple routes in a corridor often makes sense, it can lead to inaccurate results where routes are only briefly collinear -- especially in suburban areas or at transit centers. Implement a threshold distance (TBD, 1-4mi) to require routes to be collinear along a corridor for a certain distance before allowing aggregation, ensuring transit riders actually experience those frequencies for a meaningful trip distance.
• Where a route branches from a trunk, ensure we only create a major stop if both the branch and the trunk meet the frequency standard

• Research Required:

• What should the threshold distance be? Look at empirical results and bus transit trip distance research/statistics.
• Test cases: Woodland, Elk Grove, Woodman/Saticoy (San Fernando Valley), Wardlow corridor (Long Beach)

• Expected Outputs / Findings: what do you hope to have created when this is complete?

• Revised HQTA data incorporating these changes.