Manholes are covered by very heavy removable metal plates. According to Untapped Cities, a website that explores New York City, these manhole covers generally weigh between 200 and 300 pounds (90 and 136 kilograms) and are made from concrete or cast iron. Each manhole opening contains a lip around its edge on which the cover sits. These covers protect unwary pedestrians from inadvertently falling into the sewers, but also protect the sewers from debris, such as trash or organic materials, which typically collects on streets and could potentially clog sewers and water systems.
In summary, bollards with reflectors serve a multifaceted role in urban design. Their contributions to safety, traffic management, aesthetic appeal, and sustainability make them invaluable assets in modern cities. As urban areas continue to grow and evolve, the implementation of effective, reflective bollards can help create safer, more accessible, and appealing public spaces. Engaging communities in these design decisions will ensure that bollards not only fulfill their functional purposes but also resonate with the identity and values of the neighborhoods they inhabit. Through careful planning and innovative design, cities can enhance the everyday experiences of their residents and visitors alike, making urban environments safer and more vibrant.