Description You can go by rail or you can go by air. But if you have trouble, go to the National Mediation Board because it keeps the peace within these two groups. Essentially, NMB exists to maintain harmonious relationships with the air and rail transportation industries by minimizing work stoppages. It resolves collective bargaining agreement and other disputes and settles questions around bargaining representation. NMB investigates, arbitrates, and educates, all with an eye to keeping the US transportation system running smoothly. The independent agency was created in 1934 by ammendments to the Railway Labor Act of 1926.