I remember seeing an artical that gave recommended widths for streets. I’ve saved all my back issues of Model Railroader so I can go look it up if someone can tell me where.
Wandering to the top of this page to the magazine index search index
http://index.mrmag.com/
Yields 75 hits for the word “street” in the title of articles in MR backissues to #1.
For what it’s worth, side streets are about 9’ wide per lane, and highways average 12’. I found this out by wandering outside with a tape measure. I’ve also been on backroads in central Illinois that are a whopping 6’ wide total!
[:D][^]You to huh,I was checking out the width of a road a while back,had people stop and stare,my wife was with me this time,she looked at the people and said"don’t worry,he is an model raolroader" that seamed to take of it right there!![8D][:D]
JIM
Look in the current issue of Model Railroader, page 48ff - modeling modern highways. Just happened to read it last night.
[bow]
If you don’t want to buy MR just for that, take a look at: http://cid.railfan.net/t08_scenes.html#streets to give you some background on Street Widths. 
In my city the street right of way is 50’. This includes a 10’ wide section on each side for a sidewalk, curb and narrow grass plot. The home owner is responsible for this 10’ section but it is part of the R/W. Add parking on both sides of the street and the driving lanes are reduced to about 9’ as stated above.
In the real word street and roads vary greatly in width. 12’ lanes for travel and 8’ shoulders or parking lanes are the modern “standard” but probably not typical. In urban areas there would usually be sidewalks and in rural areas gravell shoulders outside the pavment.
It is generally best to model streets a little narrow so that they don’t overwelm the the trains and the (usually) selectively compressed building.
One of the most interesting urban street I’ve seen was in a little town in southwestern Washington. In the old residential area (dimensions estimated) 20’ AC pavement, 10’ unpaved shoulders, concrete curb and gutters, 4’ planting strips, 4’ sidewalks.
Incidently the street right of way width in many towns in California dating from 1850/60’s era is 80 feet. This is wider than the right of way for most post automobile streets. I have read that this was because this width was necessary to allow horse drawn fire fighting equipment to make a U-turn.
In rural areas of California the road right of way (not traveled width) of old roads varies from 30’ (very few really minor roads) to 100’ or more. 50’ probably the most common
Thanks for all the info.