The Metropolitan Transportation Authority introduced a real-time messaging system Tuesday that – if it works as intended – will let riders know if there's transit trouble ahead of time so they can plan around it.

Riders can sign up from free on the MTA's website for text messages and email alerts about unplanned service disruptions.

They will be able to customize the alerts to the subway lines and stations they use or choose from the system's 373 bus routes or nine bridges and tunnels. In turn, the agency will send up to a million text messages in five minutes about unplanned outages and major disruptions.

The system, which is based on the MTA's current email alert system for scheduled disruptions, will cost the agency $600,000 over five years.

Text-savvy New Yorkers say they could use the heads up from transit officials.

"I already get too many messages so I'm not sure how much attention I would pay to them, but it's probably a good idea," said one subway rider.

"I think it's very good because it gives people a sense of what's going on and just keep people aware," said another.

"If I got an alert every day that my subway was down or anything like that, it would help me plan out my day better," said a third.

The MTA drew criticism last August after a storm dumped three inches of rain on the city in an hour, crippling virtually the entire subway system. A task force looking into the agency's response concluded that riders may have stayed home or found another way to travel if they had known the extent of the problems.

The transit agency also wants to make it easier to receive emails and text messages below ground. Under a contract agreed to late last year, six Manhattan subway stations will have wireless access by the end of next year.

The current plan says all 277 underground stations throughout the city will be wired by 2013.