Tex. Transportation Code § 112.158

(a) This section applies only to a corporation, receiver, or other person that controls or operates a railroad or street railway the line of which is located wholly or partly in this state.

(b) An entity described by Subsection (a) is liable for damages sustained by an employee of the entity while the employee is engaged in the work of operating the cars, locomotives, or trains of the entity as a result of the negligence of any other employee of the entity, regardless of whether the negligent employee and the employee who sustained the damages are considered fellow servants.

(c) Persons who are engaged in the common service of an entity described by Subsection (a) are considered fellow servants only if the persons are:

(1) employed in the same grade of employment;

(2) doing the same character of work or service; and

(3) working together at the same time and place and at the same piece of work for a common purpose.

(d) A person engaged in the service of an entity described by Subsection (a) is considered a vice principal of that entity if the person is entrusted by the entity with the authority of superintendence, control, or command of the other employees of the entity, with the authority to direct any other employee in the performance of any duty of the employee.

(e) A vice principal of an entity described by Subsection (a) is not considered a fellow servant with other employees of the entity.

(f) A contract between an employer and employee that limits the employer's liability under this section in the event of the death of or injury to the employee or setting damages that may be recovered under this section is not valid or binding.

(g) This section does not impair or diminish the defense of contributory negligence if the injury of the employee is proximately caused by the employee's own contributory negligence.