Pink train carriages - for women and children only - should be introduced to give them ''safe zones'' at night, according to a plan by the NSW Rape Crisis Centre and the transport union.

They are calling on the government to trial the carriages next to guard carriages, from 7pm to midnight for three months.

In the pink: An artist's impression of a proposed women and children only carriage.

There were 203 reported cases of sexual assault and other sexual offences on the rail network in 2010, according to the most recent data. Women aged 18 to 29 were the most likely to be the victims.

While the rate of assaults was rising, Bureau of Crime Statistics and Research director Don Weatherburn said that given the number of passengers the rate was still low.