Even if you’re not of the nautical persuasion, you probably know that watercraft require a reliable method of mooring to the mainland. To keep ropes in place and prevent currents from sending ships seaward unexpectedly, mushroom-shaped steel and cast-iron marine bollards have been employed for hundreds of years.
The ubiquity of the mooring bollard has led to a standard test of a watercraft’s pulling power. When testing a boat’s “bollard pull,” a dynamometer or pull-scale is attached on a line between the vessel and an onshore bollard. The boat then pulls away, to measure how much drag force it has in specified conditions. This bollard pull statistic is used to describe the abilities of a vessel in the same way horsepower is used in describing a vehicle.
Yet the marina no longer is the site of most bollard installations. Today, most bollards have migrated inland, where they are used to both boost safety and beautify their surroundings.
The movement inland
In the 17th century, decommissioned cannons were used along wharfs as nautical bollards. These substantial iron posts were useful to tie off ships. Their design, either buried muzzle up and capped with an oversized cannonball, or muzzle down, so that the decorative aspects of the “cascable” were visible, also provided architectural flair. Architects and city planners saw this trend and started burying cannons as an attractive device to protect stonework against the rubbing of carriage wheels. Soon cannon-bollards were installed around important buildings. Eventually, smaller cannon-inspired bollards were designed to be used at smaller sites, as well as around gardens, tree beds, and plazas. Decorative bollards became a culturally understood way of dividing space without erecting fences or walls.
Architectural accent to safety feature
Today, the architectural use of bollards as a way of placemaking or complementing design continues. Many posts are installed for a decorative purpose and as a visual guide. In this case, an attractive design and finish are the main concern. Scratch-resistant and able to withstand the weather, these bollards are a visual border to landscape features, usually made of iron, aluminum, or steel. They are most often powder coated in black, but are available in other colors, and the coating provides both strength and durability.
Accessories have been added to traditional bollards, intended to enhance function and appearance. To make a stronger visual statement, bollards can be fitted with eyes and then joined together using decorative chains, creating a sort of visually-appealing “fence without a fence.” Other accessories may enable bike parking, provide a place for additional lighting, or create extra public seating.
Decorative posts are still used to protect stonework at the corners of buildings, or next to public phones or mailboxes, but the forces they might have to deal with are greater today than they were when bollards first moved inland. Traditional installation methods will generally only protect against the rubbing of bikes, strollers, and wheelchairs. For a bollard to capture and divert a car’s impact, it must be engineered to do so.
The evolution of installation
How a bollard is mounted is important to its function. Fixed bollards are the most common type, like the mooring bollards and cannon-bollards of old, permanently set in place.
For these fixed bollards to protect against more than just carriage wheels, they must be able to catch and divert the force of a vehicle impact. They are usually dug deep and cemented in, with just the top of the bollard visible. Yet site-specific factors such as soil conditions play a role in how this is done. When site conditions do not allow for deep mounting, shallow mounts are possible. In this case, bollards must short and broad to distribute potential impacts over a wider area.
Another evolution of our modern streetscape is that areas are often multi-use, now, and require flexibility. Plazas and walkways need to admit variable vehicle access. New removable and retractable mounts allow bollards to be removed from a site or folded into ground-based receivers to permit temporary vehicle access.
Still on the marina
These days, most bollards are not being used to test the pulling power of watercraft or keep yachts from going adrift. Yet they play an increasing role in our society. At first, moving inland, they were an attractive marker of borders and boundaries. Now they are taking on a greater, more active role, allowing for variable access to spaces in the case of removable bollards, or providing greater protection in the case of impact-resistant ones. Regardless of how their functionality evolves, they come from a tradition of enhancing our streetscapes and creating a civil culture.