# Relationship history for MSHA mine 3500522

Current hierarchy: **Thomas R  Bright → Portland Road and Driveway Co Inc → Portland Road and Driveway Co Inc**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-18T09:31:49.615908+00:00

## Valid-time edges

- **operator_operates_mine:** Portland Road and Driveway Co Inc → Portland Road and Driveway Co Inc; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Michael D  Bright → Portland Road and Driveway Co Inc; 1950-01-01 to 2013-12-31; source msha-controller-operator-history
- **controller_controls_operator:** Michael D  Bright → Portland Road and Driveway Co Inc; 1950-01-01 to 2013-12-31; source msha-controller-operator-history
- **controller_controls_mine:** Thomas R  Bright → Portland Road and Driveway Co Inc; 2014-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Thomas R  Bright → Portland Road and Driveway Co Inc; 2014-01-01 to current/open; source msha-controller-operator-history