If you have a very rectangular shape then the lip would have to be large. Stop for a moment next time you walk in an urban environment. Look for circular utili

If you have a very rectangular shape then the lip would have to be large. Stop for a moment next time you walk in an urban environment. Look for circular utility covers you see in your urban environment as opposed to squaed ones. Look at the features of the circular ones vs the non-circular ones. One of the reasons this myth irritates me so much is that everyone is so certain that they know exactly the answer but their actual daily experience doesn't line up with the results at all. I've heard several people offer explanations from a geometric safety option (which is attractive for free-standing covers) to the simplicity of manufacturing (e.g., that it's very easy to make circular molds and get even density compared to square molds) to simply what the contractor suggested. I've also heard people suggest that metal cylindrical templates were something very common to manufacture for a variety of industrial uses.