# Relationship history for MSHA mine 0400133

Current hierarchy: **RRM Development Corporation; Mitsubishi Corp → Robertson's Ready Mix Ltd → El Cajon Quarry**

- 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:** Hester'S Granite Pit → El Cajon Quarry; 1950-01-01 to 1989-07-14; source msha-controller-operator-history
- **controller_controls_mine:** Joel J  Cloud et al → El Cajon Quarry; 1950-01-01 to 1989-07-14; source msha-controller-operator-history
- **controller_controls_operator:** Joel J  Cloud et al → Hester'S Granite Pit; 1950-01-01 to 1989-07-14; source msha-controller-operator-history
- **controller_controls_mine:** Hanson PLC → El Cajon Quarry; 1987-05-01 to 2007-08-22; source msha-controller-operator-history
- **operator_operates_mine:** Hanson Aggregates Pacific Southwest Inc → El Cajon Quarry; 1989-07-15 to 2012-03-06; source msha-controller-operator-history
- **controller_controls_operator:** Hanson PLC → Hanson Aggregates Pacific Southwest Inc; 1989-07-15 to 2007-08-22; source msha-controller-operator-history
- **controller_controls_mine:** Mitsubishi Corp  et al → El Cajon Quarry; 1995-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Heidelberg Materials AG → El Cajon Quarry; 2007-08-23 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Heidelberg Materials AG → Hanson Aggregates Pacific Southwest Inc; 2007-08-23 to 2012-03-06; source msha-controller-operator-history
- **operator_operates_mine:** Robertson's Ready Mix Ltd → El Cajon Quarry; 2012-03-07 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Mitsubishi Corp  et al → Robertson's Ready Mix Ltd; 2012-03-07 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** RRM Development Corporation et al → Robertson's Ready Mix Ltd; 2012-03-07 to current/open; source msha-controller-operator-history