Manhole patterns can be of any design but are usually restricted to concentric circle pattern, basket weave or waffle. Each manhole cover has two patterns, one for the top part which is decorative, and the other for the lower half which is usually flat or designed in a spider web pattern. Neenah Foundries has pattern shops that come out with 15 to 20 new patterns every day ranging from small changes made to existing patterns to new patterns as specified by customers. CNC machines are used to construct patterns made of wood, aluminum, plastic and metal. Metal patterns are very durable and strong making them useful for manufacturing manhole covers in large scale. To allow for shrinkage while cooling, the patterns are designed to be marginally larger than the intended size of the finished manhole cover.
Another crucial aspect of bollard guards is their cost-effectiveness. Compared to other security measures, such as building walls or extensive surveillance systems, bollards offer an economical solution for improvements in safety and security. Their straightforward installation process also means that urban areas can upgrade safety measures without significant disruptions to existing infrastructure.