HCM-164 — designated 1976-10-20
Glendale - Hyperion Bridge
Los Angeles River
market / owner / federal protection sufficient; hcm is recognition overlay
HCM not needed — building would survive without it via private value or alternative protections
street view ↗ satellite ↗ big orange landmarks ↗ (bariscale, 2008) concrete (orchestrator-captured imagery is not building-aimed — use these for HITL verification)
Six-axis scores
- A. would-survive 5 probability the structure would survive market forces without HCM designation. low = needs protection.
- B. tourist currency 0 tourist and cultural currency — Wikipedia pageviews, walking-tour inclusion, public visitation evidence.
- C. subsidy efficiency 0 subsidy efficiency — Mills Act and federal HTC value vs preservation outcome. zero means no active subsidy.
- D. externality load 0 externality load — code complaints, CSR cases, 311 encampment/dumping/graffiti, vacancy duration.
- E. neighborhood health 2 neighborhood health — median household income, distress indicators, displacement risk.
- F. alternative-use value 3 alternative-use value — parcel acres, TOC tier, TPA eligibility, zoning capacity for higher use.
overall confidence: unknown
Site
- lat / lon
- 34.11275, -118.26677
- parcel acres
- 4.915670159017241 (inferred)
- typology
- infrastructure
- TPA / TOC
- no
- zoning capacity
- —
- nrhp listed
- no
- architect prominence
- —
Condition + subsidy
all "condition" fields below are proxies derived from LADBS permit history, 311 CSR cases, and code complaints. none of these directly measures occupancy. the vacancy line shows the proxy value and the specific rule that produced it; readers should treat "active" as "construction permits filed recently," not "people live or work here."
- vacancy proxy
- unoccupiable
- vacancy proxy basis
- typology non occupiable
- last permit
- 2022
- permits last 24mo
- 0
- code complaints 24mo
- 0
- CSR open cases
- 0
- Mills Act contract
- no — not in la OHR appendix a (2019 list of Mills Act properties)
- federal HTC
- no
- Wikipedia pageviews 12mo
- —
- walking-tour inclusion
- no
- median hhi (tract)
- $-666,666,666
- assessed value
- —
Contextual signals (GIS)
these are contextual proxies — signals derived from spatial context, not direct measurements of the property. they help infer hidden variables (contamination probability, structural risk) that public open-data does not measure directly. source: cal OEHHA CalEnviroScreen 4.0 (cumulative pollution burden by census tract).
- census tract
- 6037980009
- CalEnviroScreen overall percentile
- —
- cleanups percentile
- 94.3
- groundwater threats percentile
- 36.9
- hazardous waste percentile
- 47.6
- toxic release percentile
- 70.0
- lead exposure percentile
- —
- EnviroStor cleanup sites nearby
- —
- in CGS liquefaction zone
- yes — designated under seismic hazards mapping act of 1990
- type-1 contamination probability (fused)
- 0.25 — low
- type-2 structural-risk probability
- 0.70 — elevated (liquefaction zone membership combined with pre-modern-code designation date)
Narrative
history
the glendale-hyperion bridge spans the los angeles river at the point where hyperion avenue crosses between the silver lake and atwater village neighborhoods, connecting two historically distinct urban districts. the current structure was completed in 1928 (approximately), replacing an earlier crossing, and was built as part of los angeles's expanding municipal infrastructure program during the interwar period of rapid city growth. the bridge served as a critical arterial link facilitating residential development in silver lake and the northeastern communities, and its construction coincided with the broader channelization and civic engineering projects transforming the los angeles river corridor. no major catastrophic events such as flood damage or seismic retrofitting crises are confirmed in available records, though the bridge has undergone maintenance interventions consistent with its age and traffic load.
architectural significance
the glendale-hyperion bridge is a reinforced concrete arch bridge executed in a beaux-arts civic style consistent with late 1920s los angeles department of public works practice. decorative elements include ornamental railings, lamp standards, and pilaster detailing that distinguish it from purely utilitarian infrastructure of the same era. comparable extant examples in los angeles include the 1st street viaduct (1929), the macy street bridge (1926), and the north broadway bridge (1911), all of which represent the same municipal aesthetic program for civic infrastructure along the los angeles river. the hyperion bridge is notable for its relatively intact decorative metalwork and parapet detailing, though the degree of current preservation integrity requires field verification.
neighborhood context
the tract-level data for this hcm is unreliable: the median household income field returns a sentinel error value (-666,666,666), rendering axis e quantitatively uninterpretable from acs data alone. the reported population change over five years is zero, which is implausible for the silver lake–atwater village corridor — one of los angeles's most actively gentrifying subdistricts over the past decade — and likely reflects a data pipeline failure rather than actual demographic stasis. the 311-derived externality indicators (encampments, dumping, graffiti within 500 feet) return zero counts, which is atypically clean for a river-adjacent infrastructure node and may reflect incomplete geocoding rather than genuine absence of load. transit proximity is not confirmed in the fetched data, though the corridor is served by metro bus lines. | metric | value | |---|---| | census tract | 06037980009 | | median hhi | -666666666 | | 5yr δ population | 0 | | 311 within 500ft (24mo) | 0 | | encampment 311 calls | 0 | | ladbs code complaints (24mo) | — | | last permit year | — |
subsidy and condition
| field | value | |---|---| | mills act | — | | federal htc | — | | vacancy status | — |
classification reasoning
axis a (survival without protection) scores 5 at medium confidence. as public infrastructure owned by the city of los angeles, the bridge is not subject to private-market demolition pressure in the conventional sense; however, infrastructure hcms face distinct threats from capital improvement programs, seismic retrofit mandates, and traffic-capacity upgrades that can result in replacement rather than rehabilitation. a score of 5 reflects genuine ambiguity: municipal ownership provides baseline protection, but agency-driven replacement is a documented threat class for bridges of this era. axis b (tourist/cultural currency) scores 0 with unknown confidence, as no google review data, wikipedia pageview data, walking tour inclusion, or nps designation is present in the fetched record. this does not mean cultural currency is absent — the bridge is a visible civic landmark — but no data supports a higher score at this time. axis c (subsidy efficiency) scores 0 with unknown confidence; no mills act contract, federal htc, or subsidy information is available, which is expected for infrastructure typologies that operate outside the standard historic tax credit and mills act tracks. axis d (externality load) scores 0 at medium confidence; the three 311 proxy indicators all return zero, suggesting minimal documented negative spillover, though data completeness is uncertain. axis e (neighborhood health) scores 2 at high confidence per the system assignment, but the underlying hhi data is a known error value, making this score methodologically unsound. the high confidence label on axis e is inconsistent with the corrupted input data and should not be taken at face value. axis f (alternative use value) scores 0 with unknown confidence; parcel acreage, zoning capacity, and toc/tpa tier are all null, which is structurally correct for a bridge right-of-way that cannot be redeveloped as a parcel in any conventional sense. the candidate flag conditions are not met: a=5 exceeds the a_max threshold of 4, f=0 is below the f_min of 6, and overall confidence is logged as unknown rather than medium or higher. the reassess flag is therefore the correct output. the core analytical problem with this record is data completeness: three of six axes carry unknown confidence, the e-axis input is corrupted, and the infrastructure typology does not map cleanly onto a framework designed for buildings with mills act eligibility, parcel-level redevelopment potential, and conventional tourism metrics. a field validation visit and a data pipeline audit are prerequisites for any definitive classification.
sources
- la311: https://data.lacity.org/resource/h65r-yf5i.json?$where=within_circle(location%2c%2034.112745784134376%2c%20-118.26676703082812%2c%20152)%20and%20createddate%20%3e%20'2024-05-10'&$limit=1000 --- _generated by hcm-1200 orchestrator on 2026-05-10t23:13:49.000z._