On February 12, 2009, two trains collided on the Berlin U-Bahn line, resulting in the deaths of 9 people and injuring over 20 others. The crash occurred during rush hour, causing widespread panic and confusion among passengers. Investigations revealed that the collision was caused by a signaling failure that allowed two trains to be on the same track. The incident raised concerns about the safety of urban rail systems and prompted a review of the citys infrastructure. In the aftermath, Berlins U-Bahn system underwent extensive safety upgrades to prevent future accidents.