Subway problem near Union Square snarls morning rush hour commute

Train problems near Union Square caused massive shutdowns and delays during rush hour Tuesday morning along the city's busiest subway line.

A signal switch problem at 8:30 a.m. just north of the Union Square subway station forced the MTA to suspend all downtown service along the Lexington Avenue line from 125th Street to the Brooklyn Bridge and have uptown trains make local stops, the agency said.

No. 4/5/6 subway service resumed nearly an hour later, according to MTA spokesman Kevin Ortiz, though there were some delays.

The massive train problems came a day after the MTA announced four proposals to raise fares next year.

Angry straphangers blasted the agency on Twitter as they tried to navigate around the service diversions.

"No 4,5 or 6 train downtown service this morning and MTA wants to raise prices!!! They should be lowering it and apologizing," tweeted @GilesMcGrath.

The cause of the incident is still under investigation, Ortiz said.