"On national territory, a representative of the organisers and a Republican Guard will be posted at each level crossing ... and ensure the rules for crossing at that particular point," said a statement released Monday by the interior ministry, Tour de France organisers and SNCF, France's state rail company.
Any rider who breaches safety rules at rail crossings will be thrown out of the Tour, organisers said, adding that extra safety signs would be added before each rail crossing.
French prosecutors are still considering whether to press charges after several riders ignored a red light during the Paris-Roubaix race and crossed a TGV high-speed rail line just seconds before the train passed.
"Millions of television viewers saw live this extremely serious and irresponsible action which could have been tragic," SNCF said in a statement at the time.
The 102nd edition of the Tour de France kicked off from Utrecht in the Netherlands on Saturday, and passes through Belgium before entering France on Tuesday.
This year riders will have to overcome nine flat stages, three hill stages, seven mountain stages with five altitude finishes and two time-trial stages.