Silent traffic jam

The stereotypical traffic jam generally involves a lot of blaring horns along with engines being revved briefly in expectation of a 3-inch gap opening up. A couple of days ago, I was in a traffic jam on the Old Madras Road in Bangalore where there were a 100-150 cars, buses and motorbikes, yet there wasn't a sound to be heard. Not a single horn honking or engine revving or idling. Definitely creepy!