# Relationship history for MSHA mine 0501057

Current hierarchy: **Holcim Ltd → Lafarge West Incorporated → Northern Portable Plant #18**

- 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

- **operator_operates_mine:** Western Paving Construction Company → Northern Portable Plant #18; 1950-01-01 to 1987-05-28; source msha-controller-operator-history
- **controller_controls_mine:** Koppers Company Inc → Northern Portable Plant #18; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Koppers Company Inc → Western Paving Construction Company; 1950-01-01 to 1987-05-28; source msha-controller-operator-history
- **operator_operates_mine:** Western Paving Construction Company → Northern Portable Plant #18; 1987-05-29 to 1988-06-13; source msha-controller-operator-history
- **controller_controls_mine:** Koppers Co Inc & Redland Plc → Northern Portable Plant #18; 1987-05-29 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Koppers Co Inc & Redland Plc → Western Paving Construction Company; 1987-05-29 to 1988-06-13; source msha-controller-operator-history
- **operator_operates_mine:** Western Mobile Denver Aggregate → Northern Portable Plant #18; 1988-06-14 to 1998-02-10; source msha-controller-operator-history
- **controller_controls_mine:** Redland Plc → Northern Portable Plant #18; 1988-06-14 to 1998-02-10; source msha-controller-operator-history
- **controller_controls_operator:** Redland Plc → Western Mobile Denver Aggregate; 1988-06-14 to 1998-02-10; source msha-controller-operator-history
- **operator_operates_mine:** Western Mobile Incorporated → Northern Portable Plant #18; 1998-02-11 to 2002-02-28; source msha-controller-operator-history
- **controller_controls_mine:** Lafarge S A → Northern Portable Plant #18; 1998-02-11 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Lafarge S A → Western Mobile Incorporated; 1998-02-11 to 2002-02-28; source msha-controller-operator-history
- **controller_controls_mine:** Lafarge S A → Northern Portable Plant #18; 2002-01-31 to 2015-07-09; source msha-controller-operator-history
- **operator_operates_mine:** Lafarge West Incorporated → Northern Portable Plant #18; 2002-03-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Lafarge S A → Lafarge West Incorporated; 2002-03-01 to 2015-07-09; source msha-controller-operator-history
- **controller_controls_mine:** Holcim Ltd → Northern Portable Plant #18; 2015-07-10 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Holcim Ltd → Lafarge West Incorporated; 2015-07-10 to current/open; source msha-controller-operator-history