Traffic Tops for Packaged Metering Manholes

For installations where a Packaged Metering Manhole will be subjected to vehicle traffic (AASHTO H-20/HS-20) , formed reducers are necessary to transfer the load to the manhole walls.

Laminated to the top of the manhole barrel, the reducer provides a bench on to which standard grade rings / frame / cover stack is installed. Grade rings are usually concrete and the frame / cover system cast iron. However, for corrosive applications, composite grade rings (Ladtech) and frames / covers (GMI) can be used.

typical manhole grade ring frame and stack assembly

Extending up from the reducer is a 4-inch lip that helps to prevent inflow into the manhole in the event that the cover stack is not completely sealed.

Access

Openchannelflow offers a concentric 31 3/4-inch opening reducer for its 48, 60, 72, and 96-inch diameter manholes. The opening provides twice as much area for an operator to access the manhole than a traditional 22 1/2-inch reducer.

Openchannefllow also offers:

38-inch concentric
22 1/2-inch eccentric
36-inch eccentric reducers

to help customize the manhole to your particular application needs.

h-20 vehicle traffic reducer on an Openchannelflow fiberglass Packaged Metering Manhole

Vehicle (H-20) reducers are available for 48, 60, 72, and 96-inch diameter manholes. Retrofit reducer kits are also available for installations where regrading of a site calls for a new top (either by damage or use change).

Image: Hamilton Kent