# Relationship history for MSHA mine 4600001

Current hierarchy: **CRH PLC → Boxley Aggregates of WV LLC → Fort Spring Plant**

- 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

- **controller_controls_mine:** Martin Marietta Materials Inc → Fort Spring Plant; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Acme Limestone Company → Fort Spring Plant; 1950-01-01 to 1994-04-30; source msha-controller-operator-history
- **controller_controls_mine:** W H  File Jr → Fort Spring Plant; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** W H  File Jr → Acme Limestone Company; 1950-01-01 to 1994-04-30; source msha-controller-operator-history
- **controller_controls_mine:** Boxley Materials Co → Fort Spring Plant; 1991-03-01 to 2015-12-31; source msha-controller-operator-history
- **operator_operates_mine:** Acme Limestone Company Inc → Fort Spring Plant; 1994-05-01 to 1999-07-20; source msha-controller-operator-history
- **controller_controls_mine:** Ferrell Excavating Company → Fort Spring Plant; 1994-05-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Ferrell Excavating Company → Acme Limestone Company Inc; 1994-05-01 to 1999-07-20; source msha-controller-operator-history
- **operator_operates_mine:** Martin Marietta Materials Inc → Fort Spring Plant; 1999-07-21 to 2003-05-29; source msha-controller-operator-history
- **controller_controls_operator:** Martin Marietta Materials Inc → Martin Marietta Materials Inc; 1999-07-21 to 2003-05-29; source msha-controller-operator-history
- **operator_operates_mine:** Boxley Aggregates of WV LLC → Fort Spring Plant; 2003-05-30 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Boxley Materials Co → Boxley Aggregates of WV LLC; 2003-05-30 to 2015-12-31; source msha-controller-operator-history
- **controller_controls_mine:** CRH PLC → Fort Spring Plant; 2016-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** CRH PLC → Boxley Aggregates of WV LLC; 2016-01-01 to current/open; source msha-controller-operator-history