Do you pay more using the Opal card?
Transport Minister Gladys Berejiklian insists the great majority of public transport users - at least 90 per cent - will be better off or the same under the fares policy for the new smartcard.
But the minister has never provided documentation to prove this.
And now the creator of a website that allows commuters to punch in their regular trips and compare them to the cost of an Opal reckons the government could pocket nearly $100 million a year extra from higher fares, a figure Transport for NSW disputes.
That figure is derived from more than 130,000 fare comparisons the site has crowdsourced from people who have plugged their journey into the Opal or Not website.
Transport for NSW is not fond of Opal or Not, created by app developer Jani Patokallio.
After Fairfax Media reported his preliminary findings in March, the department demanded Mr Patokallio remove the Opal logo from his site.
It then sent him a 26-page list of problems with his comparisons. In a report posted late on Wednesday, Mr Patokallio addresses each of those problems, concedes a few points, but still argues a $98 million a year figure is robust enough.
Despite this, one commentator on his analysis has already pointed out that at least one of the assumptions Mr Patokallio makes when arriving at the figure may be flawed, as it assumes all train commuters purchase the cheapest paper ticket available when this may not be the case.
Transport for NSW also disputed the analysis, saying its finding were "completely false".
"The fact is the overwhelming majority of customers will pay the same or less using Opal as they would using paper tickets," a Transport for NSW spokesman said.
"The NSW government has always assumed a cost-neutral position in relation to farebox revenue."
One of the main criticisms Mr Patokallio makes of Opal is echoed by a wide range of transport academics: under the smartcard, commuters need to pay extra every time they change from a train to a bus or a bus to a train or between a ferry and another mode of transport.
This discourages transfers between modes of transport, and penalises people who live further from train stations.
Mr Patokallio was moved to create the website after noticing that he would pay significantly more under the Opal than using a ferry TravelTen ticket between his home in Abbotsford and Pyrmont, where he works about three days a week.
But he will soon not have the option of buying an adult ferry TravelTen.
Transport for NSW will stop selling 14 paper-based tickets from September, including the ferry ticket and relatively generously priced yearly and quarterly tickets.
Transport for NSW has been asked for a comment on the latest report by Opal or Not.
What do you pay under the Opal? Leave a comment below
With Ben Grubb