Monty Dean explains the various types of bollards used by the NYC Department of Transportation and their respective safety functions.

• Security bollards are designed to prevent vehicles traveling at high speeds from mounting the curb.
• Bell or Martello bollards, which are lower to the ground, are used on pedestrian islands to deter vehicles from encroaching when making turns.
• Pipe bollards are installed to prevent vehicles from parking in restricted areas or backing into infrastructure.
• While not intended for security against high-speed vehicles, pipe bollards serve specific safety and regulatory purposes.