Bush appointed a special board to address issues that have prevented 3,400 machinists and other trade workers from reaching a new contract after four years of negotiations with the Metropolitan Transportation Authority.

Federally mediated talks ended a month ago with no resolution or agreement for arbitration, clearing the way for unions to strike. No threat of a walkout has been issued.

Appointment of a presidential emergency board triggers a cooling off period until summer while the panel reviews the dispute and makes recommendations for contract terms. The recommendations are not binding.

Metro-North serves 250,000 passengers per day in New York, New Jersey and Connecticut.