Projects on multiple fronts have led to service changes on the Long Island Rail Road this weekend, and riders are being urged to give themselves extra time.

Some riders were caught off guard Saturday morning when they showed up at the Ronkonkoma station to find yellow school buses waiting for them, instead of a train.

Ongoing work to install a second track between Farmingdale and Ronkonkoma has led to service changes. There will be no train service all weekend long between Hicksville and Ronkonkoma on the Ronkonkoma branch -- riders will have to board a bus instead. The double track project is also affecting service on the Greenport branch.

Buses will also be rolling on the Port Washington line today. That's because crews are testing the positive train control system -- technology that is designed to automatically stop a train to prevent accidents.

And there's also signal testing underway this weekend related to the East Side Access project. That work means there will be less service on the Port Jefferson branch.

The LIRR says riders should give themselves plenty of time this weekend.

Several riders who spoke with News 12 Saturday morning said said they're happy to put up with a little inconvenience if it means better service down the road -- but some did say they didn't appreciate the current inconveniences.