BILLINGS, Mont. -

U.S. coal industry efforts to tap into the growing export market are struggling to gain traction.
    
Bureaucratic hurdles and resistance from environmentalists are slowing proposed mines in the Northern Plains, ports on the West Coast and now a coal-dedicated railroad in Montana.
    
The Surface Transportation Board said Friday it will take until next April to complete its draft analysis of the proposed Tongue River Railroad. That's the second significant delay in work originally scheduled for completion last year.
    
The $403 million line sponsored by BNSF Railway and Arch Coal would open the door to new mining in the Powder River Basin along the Montana-Wyoming border.
    
Coal companies want to increase exports from the basin to Asia, through new ports in Washington and Oregon. Those projects also have encountered delays.