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Plant Security
Published in Frank R. Spellman, Fundamentals of Public Utilities Management, 2020
Bollards are vertical barriers at least 3 feet tall and 1–2 feet in diameter that are typically set 4–5 feet apart from each other so that they block vehicles from passing between them. Bollards can be fixed in place, removable, or retractable. Fixed and removable bollards are passive barriers that are typically used along building perimeters or on sidewalks to keep vehicles out, while allowing pedestrians to pass. In contrast to passive bollards, retractable bollards are active security barriers that can easily be raised and lowered to allow vehicles to pass between them. Thus, they can be used in driveways or on roads to control vehicular access. When the bollards are raised, they protect above the road surface and block the roadway; when they are lowered, they sit flush with the road surface, and thus allow traffic to pass over them. Retractable bollards are typically constructed from steel or other materials that have a low weight-to-volume ratio so that they require low power to raise and lower. Steel is also more resistant to breaking than is a more brittle material, such as concrete, and is better able to withstand direct vehicular impact without breaking apart.
Plant Security
Published in Frank R. Spellman, Handbook of Water and Wastewater Treatment Plant Operations, 2020
Bollards are vertical barriers at least 3 feet tall and 1–2 feet in diameter that are typically set 4–5 feet apart from each other so that they block vehicles from passing between them. Bollards can either be fixed in place, removable, or retractable. Fixed and removable bollards are passive barriers that are typically used along building perimeters or on sidewalks to prevent vehicles from passing them, while allowing pedestrians to pass them. In contrast to passive bollards, retractable bollards are active security barriers that can easily be raised and lowered to allow vehicles to pass between them. Thus, they can be used in driveways or on roads to control vehicular access. When the bollards are raised, they protect above the road surface and block the roadway; when they are lowered, they sit flush with the road surface, and thus allow traffic to pass over them. Retractable bollards are typically constructed from steel or other materials that have a low weight-to-volume ratio so that they require low power to raise and lower. Steel is also more resistant to breaking than is a more brittle material, such as concrete, and is better able to withstand direct vehicular impact without breaking apart.
Transportation impacts modeling
Published in Zongzhi Li, Transportation Asset Management, 2018
Bollards: A bollard is a sturdy, short, vertical post embedded in the ground. It can protect pedestrians by reducing vehicular speed or limiting vehicle access to keep pedestrians away from vehicle streams. Bollards could be categorized into permanent bollards (including fixed bollard, rising bollard, security bollard, removable bollard, telescopic bollard, lay-flat bollard, and bell bollard) and temporary bollards (including flexible bollard, Qwick Kurb, breakaway bollard, and planters) based on the usage. The cost of each bollard is approximately $650–$730.
Analysis and simplified modelling of simulation of tests for medium-duty truck collision with twin anti-ram bollards
Published in International Journal of Crashworthiness, 2020
A bollard is designed with an objective of making the vehicle penetration of the threat vehicle less than the allowable value. The parameters related to the bollard and the foundation should be controlled so that the objective is achieved, under a defined threat level. The parameters of the tested bollard were analysed in the simulation study to observe their contribution to the vehicle penetration. Foundation was analysed in terms of bollard–foundation interaction and contribution of foundation on the deflection of the bollard.