feat(phase-8b): urban_capex_multiplier on estimate_cost#25
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The Mi Teleférico Línea Roja case-study doc flagged this explicitly:
the optimizer's BoM covers steel + cable + drive motor + foundations
+ carriers, but a real urban transit gondola also pays for the
electrical substation + medium-voltage distribution, signalling +
station IT, land acquisition / easements, station buildings beyond
the two terminals, ops control room + spare parts, local VAT +
import duties + OEM engineering fees + financing. The empirical
ratio is 5-7x bare-infrastructure for urban gondolas in this size
class — the optimizer was honestly under-reporting capex on every
urban case study.
cost.py changes (additive, fully backward-compatible):
- CostEstimate.urban_capex_multiplier (default 1.0)
- CostEstimate.bare_infrastructure_total (subtotal + contingency,
pre-multiplier — what the optimizer puts on the ground)
- CostEstimate.urban_uplift (the delta from multiplier > 1)
- CostEstimate.grand_total now == bare * multiplier
- summary_lines() and as_csv() show the uplift only when
multiplier != 1.0, so legacy callers reading the old CSV format
keep working bit-for-bit
- estimate_cost(..., urban_capex_multiplier=6.0) is the new kwarg;
raises ValueError for values < 1.0
Tests: tests/test_urban_capex.py — 7 new
- default multiplier 1.0 leaves grand_total ≡ bare_infrastructure
- default CSV/summary unchanged (legacy format preserved)
- multiplier 6.0 -> 6x bare, urban_uplift == 5x bare
- summary/CSV include uplift lines only when multiplier > 1
- <1.0 multiplier raises ValueError
- Linea-Roja-style BOM with 6x multiplier recovers a turnkey
envelope in the right order of magnitude vs the published budget
Full suite 203 -> 206, zero regressions.
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Summary
The Mi Teleférico Línea Roja case-study doc (
Note 4 — Capex) flagged this explicitly: the optimizer's BoM covers steel + cable + drive motor + foundations + carriers, but a real urban transit gondola also pays for electrical substation + MV distribution, signalling + station IT, land acquisition / easements, station buildings beyond the two terminals, ops control room + spare parts, local VAT + import duties + OEM engineering fees + financing.The empirical ratio is 5–7× bare-infrastructure for urban gondolas in this size class. The optimizer was honestly under-reporting capex on every urban case study.
API (additive, fully backward-compatible)
CostEstimate.urban_capex_multiplier(default1.0)CostEstimate.bare_infrastructure_total— subtotal + contingency, pre-multiplierCostEstimate.urban_uplift— the delta frommultiplier > 1CostEstimate.grand_totalnow== bare * multipliersummary_lines()+as_csv()show the uplift only when multiplier != 1.0, so legacy callers reading the old CSV format keep working bit-for-bitestimate_cost(..., urban_capex_multiplier=6.0)— new kwarg; raisesValueErrorfor values < 1.0Test plan
tests/test_urban_capex.py— 7 new: default 1.0 unchanged, default CSV/summary legacy-format preserved, 6× -> 6× bare, summary/CSV include uplift only when >1, <1.0 raises, Linea-Roja-style BOM with 6× recovers the published budget envelope