BROOKLYN - Brooklyn residents who rely on the Long Island Rail Road should prepare for massive service disruptions this weekend.Transit officials are advising commuters to use the LIRR for important business travel only, and avoid using the railroad at all if possible.There will be no service between Atlantic Terminal and the Jamaica station. Service on nearly all the other branches will be extremely limited. Officials say the changes are needed for the LIRR to update its signal and switching control system at the Jamaica station.Extremely Limited LIRR Train Service