Two lane roads come in lots of flavors! Here's a representative sample, widths given in real-world, HO and N:
Country road in central Tennessee - 22 feet paved, about 3 feet of unpaved shoulder.
(HO - 3 inches paved, 3/8 inch shoulder, N - 1 5/8 inches paved, 1/4 inch minus shoulder.)
Downtown street in old city - 35 feet between curbs. (HO - 4 13/16 inches, N - 2 5/8 inches)
Modern rural road in Texas - 25 feet paved, 8 foot paved shoulders. (HO - 3 7/16 inches paved plus 1 1/8 inch paved shoulder, N - 1 7/8 inches plus 19/32 inches.)
1990's built residential street - 45 feet between curbs. (HO - 6 3/16 inches, N - 3 3/8 inches.)
Modern downtown streets in a major southwestern metropolis - 75 feet between curbs. (only 60 feet if there's no center turn lane) in HO, that's 10 3/8 inches (or 8 1/4 inches,) while N scale gets away with a mere 5 5/8 inches (or 4 1/2 inches.)
If modeled to correct scale, streets are not narrow!
As for sidewalks, the least I've seen is 36 inches (plus a 4 inch curb,) 7/16 inch in HO, 1/4 inch in N. (in front of my house, on that 45 foot wide residential street.)
Common sidewalk widths in downtown areas range from five feet to eight feet. In any given jurisdiction they will usually be the same, since they are set by local building code. (HO - 5/8 inch to 1 1/8 inches, N - 3/8 inch to 5/8 inches)
For roads angling away from the foreground, you can use forced perspective (full size at the layout edge, narrowing as distance to rear increases) to make streets look longer.