Then you have to know what is “Tzidei Reshus Harabim KeRH”R.” The Chazon Ish has a drawing/shitah on this in his sefer, that would extend Ocean Parkway quite some distance of side streets to side streets.
It is also well known that R’ Ahron Kotler z”l would not allow an eiruv in Lakewood because of the amount of traffic on Rt. 9.