New Technology: Twist Riser Manhole Cover

A new innovation from Precision Cover Systems keeps roadways smooth
by Doyt Y. Bolling, Director, Utah T² Center

	The initial manhole cover assembly base is installed on a “Twist Riser Manhole.” This type of manhole can save municipalities $150 to $500 per installation.

Providing and maintaining a smooth and safe riding surface on roads and streets is a major challenge for local and state highway agencies, especially when the road or street is the principal corridor for utilities. Particularly problematic are the utility manholes that are made in the road surface to provide access to the utilities.

Most of us can identify with hitting a dip in the road where a manhole cover has sunk and had our car bottom out on its shocks. This is a problem in most cities around the State of Utah and for that matter in the rest of the country. A new adjustable manhole cover developed by Precision Cover Systems, Inc. provides a handy solution to the problem. This new manhole cover has been installed in Orem, Pleasant Grove, Lehi, and on the campus of Utah State University. It is currently being evaluated for ease of use, serviceability, and cost.

The "Twist Riser Manhole" as it is called is designed in such a way that it can be rotated to match the exact grade and crown of the road. The manhole fits neatly onto the concrete manhole cone providing full support for the entire assembly. This new manhole can also allow for easy height adjustments up to 2.75 inches. The adjustment is made in 0.25-inch increments. This means that roadways can then be overlaid before any additional hardware is required.

The "Twist Riser Manhole" is estimated to save municipalities anywhere from $150 to $500 per installation when personnel, equipment and materials costs are considered.

As shown in the following photographs, the assembly can be installed very easily in just a few minutes.

Prior to paving, the grade is set by rotating the bottom assembly to match the grade and cross slope of the base layer of the street or road.

The initial manhole cover assembly base is installed.

Then the top riser assembly is set to match the height of the planned surface of the pavement. The paving crew can then pave directly over the manhole cover assembly, rake the excess asphalt off the cover, and then compact the asphalt to proper grade. Excess asphalt is removed; the surface around the cover is compacted.

If minor adjustments are needed the manhole lid can be removed, the riser repositioned to the correct height and then replace the lid. The result is a manhole cover that provides a smooth riding surface.

Final result: a level driving surface!

Lawrence G. Burton, Water Reclamation Manager for the City of Orem, Utah is impressed with the product, "This new system eliminates problems by giving the user unlimited variations in height and slope to the finished surface of the manhole without disturbing any surrounding road surface."