This depends on whether you were party to a written employment agreement or a collective bargaining agreement (as a member of a union). Unless you have contractual rights for reinstatement, I do not believe that the company is required to reinstate you . After all, you were still found to be 50% at fault. That surely is enough legally to justify termination.
Nonetheless, your question does not contain all the facts and details, and it would probably be worthwhile for you to retain and consult with legal counsel.
Without a contract (individual or collective bargaining agreement) you do not have any right to the position. As an at-will employee your employer does not even have to retain your employment, unless they are discriminating against you. That being said, there is nothing that would prevent your employer from reinstating you, unless there is a department of transportation restriction (or any other legal restriction) that prevents you from performing that job.
You should speak to your employer about reinstatement and see what they say. If you do not get an answer that pleases you, call a union to represent you. People do not know the value of having a union until situations like this occur. Most transportation companies are unionized with good benefits and protections. You can learn more about unions here: Http://WWW.ibew1430.com.
Possibly, contact your union to pursue this. If they refuse to, consider retaining private counsel. That said, be forewarned that attorneys will need to charge you in order to pursue this for you. Contingency is unlikely to be available for this kind of case in my experience.
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