It is a subsidiary of Martin Marietta Materials , a spinoff of Lockheed Martin .
The Alamo Gulf Coast Railroad ( reporting mark AGCR ) is a short - line railroad headquartered in San Antonio , Texas .
Alamo Gulf Coast Railroad is a railroad of Martin Marietta Materials , a spinoff of Lockheed Martin .
The Alamo Gulf Coast Railroad ( reporting mark AGCR ) is a short - line railroad headquartered in San Antonio , Texas .