The average person recognizes manhole covers, but their specific purpose is often a mystery. Most of us go on our way without examining them.
These heavy cast iron coverings are removed to gain entry to a manhole while also providing a durable top when not being opened. Manholes are underground chambers where workers can access pipes and wires that support traffic signals, water, sewer, lights, heat and other utilities. These utility service compartments with their covers are most often found in streets where the vehicle tires repeatedly bump over them.
Manhole covers rarely pop off. It’s when they do they become objects of interest. In 1926 a gas explosion in Billings sent a manhole cover hurtling a hundred feet into the air. The heavy cover crashed to the ground near a group of workers, but no one was hurt. When gasoline seeped into the Great Falls sewer in 1969, it caused an explosion. The manhole covers all over the northside of Great Falls blew off. In 1998 in Helena, hydrocarbons in the sewer ignited and created an explosion causing manhole covers to blow off and setting fire to brush nearby.
These silent guardians also come off when excess water causes them to float. Occasionally Montana cities will get several inches of rain in a sudden downpour. The gutters can’t handle the excess rain, so the water backs up and the covers float off to be replaced by utility personnel after the storm.
An incident in Ann Arbor, Michigan, proves how important manholes and their covers are to maintenance of city utilities. When the streets received a new layer of asphalt, the whole street was covered without thought to the manholes. The city had to hire someone with a metal detector to go around the city and identify their location, so the covers could be dug up.
These pieces of metal in our streets are round for several reasons. A heavy metal manhole cover falling on a utility worker who was in the manhole would be a real blow (literally!). Because of their shape, it is impossible for round covers to fall into the hole unlike a cover that has square edges. Since they are round, heavy covers can be rolled into position. Rotational tools for creating manholes are circular, so round manholes and their covers are a good fit. And finally, the volume of material required to manufacture a round manhole cover is a little less than what is needed to manufacture other shapes.
In Mimi and Robert Melnicks’ book, Manhole Covers of Los Angeles, they write, “…manhole covers present an infinite variety of design in the commonplace as a record of defunct utility companies, forgotten business firms, and obsolete foundries. Manhole covers forming urban industrial art [have their] place in American culture.”
The city of Seattle decided to do something different than casting the usual tread design on the covers. Instead, a city map was imprinted. The idea came from Europe where a Seattle utilities’ employee saw decorative manhole covers. In Lillehammer, Norway, the symbol of the 1994 Olympic Games was designed for its covers. They were so popular that the utilities company had to replace a few that strangely disappeared.
Cities throughout the United States have created unique designs for covers that market their community. For instance, the City of Bisbee, Arizona cover features a mining car filled with gold nuggets. The desert town of Peoria, Arizona, designed a cactus and the sun peering over a mountain for its cover. Jacksonville, Florida manhole covers feature a picture of Andrew Jackson for whom the city was named.
Cities in Montana have gotten into the act and have contracted for unique manhole cover designs. The official symbol of Helena is a drawing of “The Guardian of the Gulch” that represents the tower standing on “Tower Hill. The covers at Big Sky, Montana, feature its mountains. The design on the Bozeman cover represents the city’s seal celebrating the city’s beginning. D&L Foundry in Moses Lake, Washington, has cast covers for these Montana cities and also the unique designs for Missoula, Kalispell, and Billings.
Essayist and poet, David K. Leff writes, “More than fascinating objects to look at, manhole covers give me hope. They restore my faith that the utilitarian can be beautiful, that the mundane can be an ornament that the ordinary can intrigue.”
The next time you take a walk, you may be surprised at what you find in the artistic design on the manhole covers in your city’s streets, so don’t forget to look down as well as up. MSN
