Friendly Route Protection
Why People Get This Wrong
People often assume that the "Friendly Route Protection" means they can't block a new player at all during their first two turns, which leads to arguments about what exactly constitutes blocking or when it's allowed. The confusion arises because the rule specifically mentions only claiming both connections into the same city, not outright preventing a route from being played at all.
Official Verdict
During a player’s first two turns, opponents may not claim both connections leading into the same city solely to trap that player. This informal courtesy is useful when teaching but requires good-faith judgment and is not recommended for competitive play.