Train from Warsaw to Kiev, Ukraine

Traveling from Berlin to Kiev, I was a little worried when police, or military took my passport and walked away with it. Soon we pulled into what looked like a warehouse and my train started rising up into the air. The train is shunted into the gauge-changing shed at Yagodin (the Ukrainian frontier point) and jacked up to have its wheels changed from standard European (4' 8½") gauge to Russian 5' gauge. Apparently, Ukraine has different track sizes. This was changed in the second world war to prevent the German's to enter Russia. And the Ukrainians haven't bothered to change this in the past 50 years.