The lorry in pripyat is able to be got onto if you team with a seeker. Making so if you do get teamers its impossible to get to the hiders on top of it. But once your on top your also able to be boost outside the map or on top of the trees making it impossible for seekers to get you. i have lost many games due to it and find it very annoying.
Thanks for submitting a bug report.
There is a pending fix on this map that should fix this issue in due time, but you can also report these people for Teaming or Exploiting as either way bother are breaking our rules.