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 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 platform serving one of the new SG tracks from the north as the previous interchange island has been demolished.
Prior to its being withdrawn on 15 December 2013 whilst the "Rail Baltica" project work was underway, PKP worked a service from Warszawa to the then limit of standard gauge track at Šeštokai. There was an "SUW2000" gauge changing system at Mockava, which was used only by the overnight passenger train between Warszawa and Vilnius until withdrawal after 28 May 2005.