Birmingham's New Street station could be hit by "taxi wars" with council chiefs set to allow any hackney carriage to pick up passengers there.
Currently only 1,000 members of the Birmingham and Solihull Taxi Association can use the lucrative New Street ranks, serving 135,000 passengers.
But from July 31, all hackney carriages in Birmingham - about 1,600 - will be able to use it.
Network Rail is aiming to install a barrier where drivers will swipe a card to be allowed in. Each entry will cost 20p, which will be added on to the taxi fare.
The B&S Taxi Association has predicted gridlock, with potential flashpoints between drivers.
Secretary Mike Shingler said: "It could be chaos. They already queue out onto the street and it will only get worse." In the past, police have been called to confrontations between drivers around the station area.
Ron Pearson, a cab driver with the Transport and General Workers Union, said: "They have controlled the ranks for a long time so it is good that everyone else can have a chance."