When a small hole in the road is a window into a bigger hole that is so deep it can swallow most of a broom handle, a collapse is only a matter of time.

With all the precipitation we’ve had this summer, the city’s network of storm sewers has often worked overtime to clear the rainwater that has drained into them.

The sheer volume of water during a long, hard rain creates a lot of pressure in the storm sewer infrastructure. Not surprisingly, weak points in aging pipes sometimes fracture and allow water to seep into the surrounding road bed.

And when it does, the road bed material is washed away, creating a hollowed-out area beneath the pavement that can buckle from the weight of vehicles passing over it.

That may be the best explanation for a hole in the pavement at the southeast corner of Broadview and Withrow Aves., which appears to be a portal to a large cavity beneath the street.

Michael Nitefor sent us an email about it, saying the hole developed earlier this summer, but so far, the only thing the city has done about it is spray-paint a red circle around the empty space.

He estimates the hole “is about four feet deep,” a sizable subterranean chamber along the curb of a street as busy as Broadview, and no doubt susceptible to a cave-in.

How did Nitefor estimate the depth of the hollowed-out area? He stuck a broom in the hole, which we found to be an effective (and amusing) measuring stick.

He added that he’s waiting for “a catastrophic pavement collapse,” since the hole has been there for several months without the city doing anything about it.

We went to Broadview and Withrow and peered into the small hole, which revealed a much larger and deeper open space. The only reason the pavement hasn’t buckled is that Withrow is one-way westbound, and northbound traffic on Broadview can’t turn right onto it; otherwise vehicles would drive right over the hole.

STATUS: Ellen Leesti, a spokesperson for Toronto Water, emailed to say they’re working with transportation services to determine the cause of the cavity and will repair it as soon as possible.

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