# Relationship history for MSHA mine 4503623

Current hierarchy: **CRH PLC → American Rock Products → ARP Prtbl Crusher WP/Kolberg**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **controller_controls_mine:** CRH PLC → ARP Prtbl Crusher WP/Kolberg; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** CRH PLC → ARP Prtbl Crusher WP/Kolberg; 1987-09-18 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Central Washington Concrete → ARP Prtbl Crusher WP/Kolberg; 2006-11-29 to 2023-08-21; source msha-controller-operator-history
- **controller_controls_operator:** CRH PLC → Central Washington Concrete; 2006-11-29 to 2023-08-21; source msha-controller-operator-history
- **operator_operates_mine:** American Rock Products → ARP Prtbl Crusher WP/Kolberg; 2023-08-22 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** CRH PLC → American Rock Products; 2023-08-22 to current/open; source msha-controller-operator-history