The MBTA commuter rail and subway lines are experiencing multiple weather-related delays and commuters are being told outright to avoid the Red Line if possible.

A T spokesman said Tuesday that a week of constant exposure to frigid temperatures, ice, and snowfall has taken a toll on vehicles and infrastructure.

The National Weather Service says temperatures early Tuesday could fall to 17-below with wind chill.

Although all T modes are being affected, the Red Line is a particular issue because of a shortage of fully functioning subway cars.

MBTA General manager Beverly Scott said it could be days before things are back to normal.

Boston area highways were also in virtual gridlock on Tuesday.

A six-car Red Line train with about 50 passengers was stranded for about two hours on the tracks near the Braintree station on Monday.