At Traylor Bros Inc. (TBI), building bridges and tunnels is a family affair. The family-owned heavy/civil construction company mostly builds suspension and segmental bridges, dams and ports, storm sewers, and transmission lines. Its Underground division works on tunneling projects, while its Traylor Mining, LLC subsidiary works on underground mining projects and facilities for copper, gold, and coal mine development in North America. TBI is perhaps best known for its work for the San Francisco's Bay Area Rapid Transit (BART) system and the I-10 span bridges over Lake Pontchartrain in Louisiana. Civil engineer William Traylor founded TBI in Indiana in 1946.