Crowd barriers, also known as crowd control barriers or crowd control fencing, are physical barriers designed to control pedestrian flow in retail, commercial, or office spaces and to help maintain queues of waiting attendees. When these barriers are interlocked, they form a more effective line of several impenetrable defenses. The lines don't snap easily and don't offer any gaps to straddle or topple over, providing great crowd control. It is often used in major public events such as sports events and concerts to control the crowd flow, make the crowd move in an orderly manner, and avoid stampede accidents.