# Relationship history for MSHA mine 0503022

Current hierarchy: **Bechtel Group Inc → Bechtel Operating Service Corp → Martinez Mine**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **operator_operates_mine:** Chimney Rock Coal → Martinez Mine; 1976-11-01 to 1984-01-04; source msha-controller-operator-history
- **controller_controls_mine:** J H R Corp Et Al → Martinez Mine; 1976-11-01 to 1984-01-04; source msha-controller-operator-history
- **controller_controls_operator:** J H R Corp Et Al → Chimney Rock Coal; 1976-11-01 to 1984-01-04; source msha-controller-operator-history
- **operator_operates_mine:** Bechtel Operating Service Corp → Martinez Mine; 1984-01-05 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Bechtel Group Inc → Martinez Mine; 1984-01-05 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Bechtel Group Inc → Bechtel Operating Service Corp; 1984-01-05 to current/open; source msha-controller-operator-history