Manhole Top Styles

When you’re looking to install packaged metering manholes for your flow rate measurement needs, there are several top styles to consider. The kind of top you have on your manhole plays a major role in its overall functionality and how it interacts with the surrounding environment. Learn all about the various styles of manhole tops, and discover which would work best for your flow rate measurement needs.

Domed Tops

A domed top for a manhole is the most popular option thanks to its easy application, convenience and durability. Dome-shaped tops are typically designed to stick out about a foot above grade, making the manhole relatively easy to notice. Because of this, they aren’t used often in heavy traffic areas. While they are tested for vehicular loads, there will be trouble if a speeding car ever hits one. Pedestrian traffic can be hurt by these as well, because they’re trip hazards. 

One of the more appealing features of domed tops is the standard fail-open gas struts. These handy features make opening the top easy, and they can ensure that the top stays open. A gas strut greatly reduces the likelihood of a worker or monitor getting stuck in the manhole due to the top closing. Without access to the strut, unauthorized parties won’t be able to get into the manhole as well, so there’s additional security.

Hatch Tops

A hatch top allows a manhole to be at the same level as the surrounding grade. They are most commonly used in high pedestrian-traffic areas, as walking from the surrounding ground over the hatch top of a manhole might not even be noticeable to passersby. Additionally, hatch tops allow for much wider manhole openings, which can make access for workers easier. 

While hatch tops are useful at helping a manhole blend in with its surroundings, there are a few additional factors to consider. The first is that hatch tops aren’t inherently designed to be watertight. If there are heavy rains or floods, water can drip down the manhole to potentially reach a vault with a flume inside. Additionally, these hatches are not rated for vehicular traffic. While the weight of a human won’t do any damage, these tops could collapse under the weight of a car.

Traffic Reducer

As the name may suggest, a traffic reducer top is designed to withstand vehicular traffic. These are the kind of tops that need to be used when a manhole is located in the road. They use specially made mounts and frame stacks to withstand an immense amount of weight without caving in. Additionally, these manholes often feature extra protection because vehicle traffic has a higher risk of causing microbial-induced corrosion.

When though traffic reducer tops may be placed in a popular area, they aren’t at much risk of being vandalized. Lightweight stack types don’t have any scrap value, so no one will take the cover for a profit. That’s only true, however, if you opt for certain materials. Cheaper and heavier materials are not only harder to operate, but they do have a scrap value.

Packaged Metering Manholes From Tracom

With these manhole top styles in mind, you’re in a better position to get a packaged metering manhole of your own. That’s where Tracom can help. Learn more about our fiberglass manholes, and contact us today to start your own design!