Trouble on Skytrain and Translink is telling Surrey commuters to get to the stations early.

Due to a mechanical issue, Skytrain is running reduced service - running single-track, alternating directions, between 22nd St Station and Metrotown.

The Millennium Line is running separately, between VCC-Clark and Columbia and turning back.

Additional trains will be put in service between Commercial-Broadway and Waterfront.

Customers -- particularly those using Surrey stations -- should expect major delays and should plan on leaving early.

Translink isn't sure when technicians will get the problem fixed.