A planned rail strike in the northwest and east of the Netherlands will proceed on Tuesday after unions and national train operator NS failed to reach an agreement on Monday. The strike, the fourth in two weeks, will impact commuter traffic significantly.

The strike is organized by rail unions VVMC and FNV and will primarily affect the area around Arnhem, Nijmegen, Hengelo, Enschede, Zutphen, Haarlem, Alkmaar, and Amsterdam. Services will halt starting at 4 a.m.

The NS is currently evaluating the impact of the strike, but has not yet confirmed whether services to Schiphol Airport will be affected.

Monday’s negotiations between the unions and the company, aimed at preventing further industrial action, were described as “disappointing” by FNV negotiator Henri Janssen, speaking to broadcaster NOS.

Railway workers are demanding a 6% pay increase. NS has offered a 3.25% raise this year and 2.75% next year.

In addition to the pay raise, unions are seeking better early retirement options for employees involved in physically demanding work.

Two other rail unions, CNV and VHS, do not support the strike planned for Monday and wish to continue negotiations. International train services have not been affected by the strikes thus far.