Why do you sometimes see a row of square holes dug in the street?

Dear Cecil: Every so often we see a work crew dig four or five squares in a row out of the street, cover them with a marker for a day, then surprise, fill them in with cement. What is the point of this? David D., Chicago

Cecil replies:

Dear David:

Who says there has to be a point to everything? Not only would it make life tedious beyond description, this hard-working columnist would be out of a job. That said, the workers probably aren’t digging those holes for grins–most likely they’re employed by a local utility. Since we’re on sort of a gas theme today, let’s assume it’s the gas company out looking for a leak. First they check the obvious places where gas collects, like catch basins and manholes. If this proves unavailing, they drive a steel bar into the pavement to see if gas has percolated through the soil. Still nothing? Time to get serious and dig a series of two-by-two-foot holes along the route of the gas main, paying particular attention to joints and connections. The leak having been found, the crew digs a bigger hole, makes the necessary repair, and moves off to snarl traffic somewhere else.

Cecil Adams

Send questions to Cecil via cecil@straightdope.com.