Independent research and development of PG4 (U78CrV) annual volume of traffic in the world's largest rail laid daqin railway, the new moon yellow railroad, zhang tang railway and central south channel, line with small radius curve, large vehicle axle load, rail force more demanding, etc. PG4 rail online after the operation, the rail wear and contact fatigue performance is good, is China's largest production base of overloaded railway rail, is also a important overloaded railway rail supplier in the world. The export of overloaded railway rail in the United States, Brazil, Australia and other countries, well received by users.