# Relationship history for MSHA mine 4503343

Current hierarchy: **CRH PLC → Central Pre-Mix Concrete Company → PORTABLE PLANT #1**

- 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 → PORTABLE PLANT #1; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Hanson PLC → PORTABLE PLANT #1; 1988-11-14 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Acme Materials & Construction Company → PORTABLE PLANT #1; 1995-10-01 to 2000-06-29; source msha-controller-operator-history
- **controller_controls_operator:** Hanson PLC → Acme Materials & Construction Company; 1995-10-01 to 2000-06-29; source msha-controller-operator-history
- **operator_operates_mine:** Central Pre-Mix Concrete Company → PORTABLE PLANT #1; 2000-06-30 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** CRH PLC → Central Pre-Mix Concrete Company; 2000-06-30 to current/open; source msha-controller-operator-history