Okay, I have to admit it, I want to know what's going on when I see holes being dug, streets being scraped, men going down into openings in the street. Agatha Christie's Miss Marple called such people "nosy parkers," and I guess I'm one of them. After all, "inquiring minds just want to know." When I saw these men with their big truck with all the dials and indicators, I couldn't resist.
As it was explained to me, the truck is a rolling vacuum cleaner of sorts, which they use to suck stuff out of the city water lines. The sections of tube were attached to an opening in the water line, then connected to the truck. When the vacuum was turned on, things such as gravel that might have eventually blocked the line were sucked into the tank on the back of the truck.
Duly impressed, I thanked them for their information, then asked if, when they were done with their shift, they might come over to vacuum out my place; it needs more help than Hoover, Dyson or Oreck can handle.