THE number of commuters using Dublin's integrated ticket for public transport -- known as a Leap card -- has doubled in the last year.
However, thousands of passengers are still being overcharged by the system -- which is set to be rolled out in Cork city in the coming months.
Figures obtained by the Irish Independent show that more than 6,000 people obtained refunds in the first 11 months of the year because they were overcharged.
Nearly 600 passengers a month sought money back this year, mainly because of faults on Irish Rail ticket validators.
This meant they were charged the maximum fare because they couldn't tag off at a station to qualify for the lower fare applicable to shorter journeys.
The National Transport Authority (NTA) said that 384,689 Leap cards had now been issued, which is up more than 190,000 in the last 12 months.
Some 6,352 journey refunds were processed in the year to the end of November, but this was out of nearly 19 million journeys, which the NTA said compared favourably with other European systems.
The level of refunds is below the 7,500 issued last year, even though twice as many people are using the pre-paid Leap card system when travelling.
"Isolated incidents of validators temporarily going offline is the main cause of refund requests in Irish Rail stations," the NTA said.
Most stations had several validators so customers could tag off at different ones, but the NTA is working with Irish Rail to provide additional machines where there is only one or two.
Rail Users Ireland said that many more could have been overcharged but weren't aware or didn't bother contacting the operators to get their money back. Spokesman Mark Gleeson said Irish Rail should sort out the software issues still causing glitches and overcharging after two years of the system being operational.
"There's bound to be occasional issues on any system, but there's no reason why Dart stations should be worse than Luas ones where there are hardly any problems with the same validators," he said.
However, there had been positive developments this year, including the introduction of daily and weekly fare caps in recent weeks.
This means commuters who make multiple short trips do not pay any more than €10 per day, or €40 a week, on public transport services in Dublin, with lower caps on individual services such as the Luas or Dublin Bus. Mr Gleeson said Dublin was the first city in Europe to have a weekly fare limit on its travel network.
"Many systems like the one in London have daily limits, but Dublin is pretty far ahead of the game on the weekly cap," he said. The Leap card system is also set to be rolled out on Cork's commuter services in April, meaning card holders will be able to use the same system in both cities.
Passengers using pre-paid Leap cards get discounts of up to 23pc on short-hop fares compared with those who pay cash, meaning there's a strong financial incentive to use the system. The free travel pass system for elderly and disabled passengers is also set to be switched on to the Leap card system.
Transport operators are hoping this will end serious abuses of the existing paper system where out-of-date or invalid free travel passes are frequently used.