To break even by 2015, daily patronage need to increase by 61 per cent in both directions, while ticket prices need to increase by 40 per cent.
"In practice that will see KiwiRail attempting to grow patronage while increasing fares about 10 per cent year on year. We know this will be very challenging."
Currently, an average of 174 passengers a day travel from Otaki station and north, while 116 travel from Waikanae and further south.
The average passenger ticket price is $10.29.
Ms Hume said commuters and councils who have made strong calls for keeping the service needed to encourage more people to use it every day.