Buses will replace trains this weekend between Ronkonkoma and Central Islip on the Long Island Rail Road, the railroad said.

The work from late Friday to early Monday calls for switch installation and related track work for the double-track project, the railroad said.

Riders to or from Ronkonkoma should plan for at least an additional 23 minutes of travel time or consider using the Port Jefferson Branch or Montauk Branch as alternatives, or take advantage of free parking at Brentwood and Deer Park, the LIRR said.

The LIRR issued this advisory:

advertisement | advertise on newsday

  • Eastbound riders traveling to Ronkonkoma from stations in New York City, Nassau County or western Suffolk County will board their regularly scheduled Ronkonkoma-bound trains and get off at Central Islip to connect with buses traveling to Ronkonkoma. Customers should plan for up to an additional 23 minutes in travel time.
  • Customers traveling to Medford, Yaphank, Riverhead, Mattituck, Southold or Greenport will board their regularly scheduled trains (the 9:12 a.m. or 2:12 p.m. departures from Penn Station) and get off at Central Islip to connect with buses traveling to Ronkonkoma.
  • At Ronkonkoma they will connect with trains making all stops to Greenport. The trains from Ronkonkoma will be timed to meet the buses and will arrive at all stations 23 minutes later than normal.
  • The 4:39 p.m., 5:39 p.m. and 6:39 p.m. trains from Penn Station, which normally travel to Ronkonkoma, will instead terminate at Farmingdale. Customers traveling to Wyandanch, Deer Park, Brentwood, Central Islip or Ronkonkoma should take trains that depart Penn Station at 4:12 p.m., 5:12 p.m., 6:12 p.m. or 7:12 p.m.
  • Riders from Ronkonkoma to points west will find buses to take them to Central Islip for regularly scheduled train service. Buses will depart up to 23 minutes earlier than regularly scheduled trains.
  • Riders from Greenport, Southold, Mattituck, Riverhead, Yaphank or Medford to points west of Ronkonkoma will board trains 32 minutes later than normal schedules.
  • At Ronkonkoma, riders will connect with buses to Central Islip for continuing train service. Upon boarding their station of origin, customers should plan for up to 28 minutes of additional travel time, and will arrive at western terminals one hour later than normal.
  • The trains that normally originate at Ronkonkoma at 10:05 a.m., 11:05 a.m. and 12:05 p.m. will instead originate at Farmingdale, at their usual times.
  • Riders from Central Islip, Brentwood, Deer Park and Wyandanch should take the trains that will originate at Central Islip at 9:47 a.m., 10:47 a.m., 11:47 a.m. or 12:47 p.m. and will make all stops along the branch.
  • The train that normally departs from Ronkonkoma at 11:19 p.m. and is due into Penn Station at 12:44 a.m. will originate at Central Islip at 11:40 p.m., 14 minutes later than normal. It will arrive at Penn Station at 12:59 a.m.
  • Bus connections from Ronkonkoma are adjusted accordingly and listed in a special timetable available at mta.info, the LIRR said.
  • Riders on this train traveling to Brooklyn will connect at Jamaica with a train that arrives at Atlantic Terminal 27 minutes later than normal.

The $387 million double track project is expected to increase capacity along the 18 miles between Farmingdale and Ronkonkoma. Completion is targeted for the end of 2018.