Crowd control - create a safe area for crowds entering or exiting a venue, or use the barriers to keep crowds from entering an area. The mass of each barrier ensures that they can't be tampered with to create an opening.
Security - create a temporary or permanent physical barrier for protection of assets or personnel. Protect Shop fronts, carparks, government buildings, airports, subdivisions, anything that needs to keep vehicles or people entering.
Farming/Agriculture - use to separate your feed lot, or create storage bins