Despite Seoul City’s efforts to curb illegal subway rides by charging a fine of 30 times the original fare, such rides are still on the rise, subway operators said Friday.

According to Seoul Metro and Seoul Metropolitan Rapid Transit, which respectively operate Subway Lines No. 1-4 and 5-9, more than 42,814 passengers illegally hopped on trains last year, paying almost 1.7 billion won ($1.5 million) in fines.

In 2015, the number of illegal riders stood at 42,289, paying about 1.5 billion won in fines.

The most frequent tricks were bypassing the turnstiles without tagging a metro card, going through the special turnstile designed for the handicapped or tagging someone else’s transportation card.

The rise was especially conspicuous in the number of those using the discount pass of a family member -- who is either aged 65 or above, a student or physically handicapped -- according to Seoul Metro.

“While the number of those who hopped on a train without tagging a metro card seems to be diminishing, those who use someone else’s card to receive a price discount has largely gone up,” said the SMRT official.

“Senior passes, only distributed to citizens 65 years or older, are frequently used by elderly people at a younger age, or even by their grandchildren.”

Another subway official said it is physically difficult to crack down on such illegal riders, as it frequently leads to quarrels between subway staff and passengers.

“Even when they are caught, many of the illegal riders refuse to give their personal information and even reproach subway staff members for levying fines on them,” a Seoul Metro official surnamed Park who works at City Hall station told The Korea Herald.

“Clashes often break out as we are neither the police nor have the official right to interrogate passengers,” Park added.

According to the Seoul Institute released report last year, 724 billion won worth of extra burden is needed each year to manage Seoul’s subway operations during times of congestion.

To reduce the burden, Seoul’s subway operators should consider adopting a differential fare system, charging passengers more during peak times, the report suggested.

By Kim Da-sol (ddd@heraldcorp.com)