Tejada, an employee of the construction company ARB in Pittsburg, had been laying pipe in the area, according to Sgt. Bryan Reynolds at the coroner's office.
Bill Griffith, regional safety manager for ARB, confirmed that Tejada was an employee at the company but couldn't comment on the incident because it is still under investigation.
The California Highway Patrol reported that the collision happened in the area of North Broadway Avenue and Willow Pass Road in unincorporated Contra Costa County.
Amtrak spokesman Marc Magliari said the crash occurred at about 3:15 p.m. at a private crossing on BNSF Railway tracks. There were no reports of injuries to crew or passengers on the Oakland-bound Amtrak train No. 713, he said.
Tejada was taken to John Muir Medical Center in Walnut Creek, where he died.
The train was delayed by about an hour and a half, Magliari said.