roads, parking lots and sidewalks - Model Railroader Magazine

"Standard" road widths have not changed since the 1930-40's.  The largest automobiles then were the same size (or even a little larger) than the largest automobiles today.  In the 1920's there were some trucks on the roads that would not be legal today because of their width.

This for residential streets. It is from the 1940's.  It is "typicial" not "standard and there are many exceptions in the real world:

STREETS_zps82bbd366 by Donald Schmitt, on Flickr

Minimum recomended sidewalk width 4'.  Recommended planting area between sidewalk and steet (if there is a planting area) 3' without trees, 7' with trees.

 A few years ago  I drove by a house I lived in the 1950's  then it had approximately 18' of pavement (for two way traffic)  gravel parking areas on both sides (each wide enough to parallel park cars, curb on both sides, planting strip and sidewalk on both sides.   It had not changed.

An 18 foot wide dirt road is reasonable for a dirt road in the 1950's, It provides enough width for vehicles traveling in opposite directions to get by each other without too scareing most drivers. 

 I currently live in a very rural mountainous area of California.  While the main County roads are paved 24'-26' wide.  There are many miles of unpaved County roads.  A few are actually wider than the paved  roads (generally due to improvements to facilitate recent logging operations), but most are 10' or  less wide with few turnouts.  These roads are virtually unchanged since the mid to late 1800's when they were cut through the forest by miners, loggers and farmers in the area.

Dirt roads in the flatlands were generally built wide enough to accomodate twio way traffic.

The following info for parking lots could also be applied to streets.

PARKING2_zpsc18dd086 by Donald Schmitt, on Flickr

PARKING1_zps01e9fb83 by Donald Schmitt, on Flickr

Commercial streets would generally be paved wide enough to accomodate 2 or 4 lanes of traffic plus angled parking on both sides although parrallel (0-degree) parking is not really rare. Sidewalks 5' to 10' wide. Probably most in the 5-6' range.

I tried to sell my two cents worth, but no one would give me a plug nickel for it.

I don't have a leg to stand on.