Radio New Zealand - Te Reo Irirangi o Aotearoa

Auckland's newest commuter rail service is being cut after little more than a year because too few people used it.

The service to Helensville in the rural northwest will end after Christmas, having attracted just half the level of patronage needed to make it viable.

The Auckland Regional Transport Authority says the almost 50 kilometre extension of the western line service drew on average 14 passengers in each journey, and numbers fell through the year.

Community campaigners in Helensville had claimed success last July when the rail service was restored to their town.

The authority said it cost $45 in subsidy for each train passenger's journey, and the bus service is more frequent and quicker.