A strike by the Korean Railroad Workers' Union is to begin Thursday morning, raising concerns over transportation and logistics turmoil.

According to unionized workers at the state-run Korea Railroad Corp., also known as Korail, the union will go on a four-day strike from 9 a.m. Thursday to 9 a.m. Monday.

The strike is the union's first since November 2019. Members voted 64.4 percent in favor in a strike ballot at the end of August.

The railway union's requests include the expansion of public railroads and the full implementation of a four-group, two-shift schedule. The implementation of this shift schedule, in which two of four groups of workers work 12 hours a day, while the other two groups take a break, has been delayed for more than four years.

While total annual working hours are the same in both the current and proposed systems, the four-group, two-shift schedule results in workers having more days off. The disadvantage for management is that it requires more workers.

The expansion of public railroads includes the introduction of KTX services between Busan and Suseo Station in Seoul to resolve passenger inconvenience, decreasing the fare gap between the KTX and SRT, and the integration of Korail and SR.

Korail and SR operate KTX and SRT trains, respectively.

The SRT was launched in 2013 with the aim of improving services through competition within the high-speed train market, providing an alternative to the KTX. The railway union considers the expansion of the SRT as an attempt to reduce Korail's public role.

The union has held a total of seven negotiation sessions with management since July, but failed to reach an agreement. The mediation by the National Labor Relations Commission also broke down.

The union said that it may stage a second strike depending on the management's response. In the past decade, there have been four general strikes by railway unions, in December 2013, September 2016, October and November 2019. Among them, the 2016 strike was the longest at 74 days.

In the most recent strike in November 2019, unionized workers called for 4,000 additional workers to be recruited to introduce a four-group, two-shift system. The freight train operation rate was only 20.7 percent at the time, causing nationwide turmoil.

The government launched an emergency task force on Wednesday to minimize disruptions from the strike. The task force said it will secure the frequency of the subway and KTX during rush hour at 70 percent of the usual level and allocate additional intercity buses.