In Mas. Sh'kalim, 20A, the gemara discusses whether one can consume meat or cheese that he finds in a public space. One reason to allow it is because "רוב מהלכי דרכים" most of the travelers in those cases were Jewish so the item was not forbidden due to a concern that it was of non-Jewish origin.
Unlike a situation where one can count the number of butcher shops, the number of travelers is not static. I live in a relatively "Jewish" town and in a neighborhood with a large percentage of Jews, but the streets are public and people can walk (or drive) through to get to different places.
How, practically, can one determine if a road or large common area has a majority of Jewish travelers on it (on one day? over a year? what about tourist season when many non-Jews visit)? Does the road have to be a dead end so no one other than residents would walk/drive down it and one can count who lives on that block?
I'm not asking for a psak based on my address because roasted kid and cheese wheels are often spotted on my block; I am trying to understand the halachic mechanism.