Note that there is a one hour time difference between Lithuania and Poland
(Šeštokai -) Mockava LG - Trakiszki PKP (- Suwałki)
[D] Standard gauge [1435 mm] track crosses the border and continues to Kaunas as "Rail Baltica". There is broad gauge [1520 mm] track north of Mockava, interlaced with the standard gauge track as far as Šeštokai. A limited FSSuMO standard gauge service between Białystok and Kaunas operated by PKP diesel units commenced on 17 June 2016, but these only commenced calling at Šeštokai on 6 October 2017 at a new platform serving one of the realigned SG tracks as the previous interchange island had been demolished.
PKP had previously worked a service from Warszawa to the then limit of standard gauge track at Šeštokai until it was withdrawn on 15 December 2013 whilst the "Rail Baltica" project work was underway. Prior to 28 May 2005 there had been a through overnight passenger train between Warszawa and Vilnius using a "SUW2000" gauge changing system at Mockava.