From Wikipedia ...

For a model railroad, I'd keep things on the narrower side, like 9-12 feet. I use 10 feet for the lanes on my roads and since they're not freeways or other major roads, they look fine. Here's Highway 42 on my Siskiyou Line layout and it uses 10-foot lanes:

Dagenham

you mention a 'road'...is it a rural-ish paved State highway?  If so wondering if you have a shoulder or not.  Joe's pic above doesn't really have one, so maybe that is making things look off if you added one?  Without actually measuring, I've taken a few HO scale cars and trucks and added what looked 'right' on either side...do the mirrors of two on-coming vehicles smash into each other?? Too close!

There's DOT standards on such things, but I think roads in model railroading are sorta like trees- if they are actually to scale in some instances, they just look huge.  There are some old, 'locked in time' small towns I've driven through, where it seems things get really wide as you enter town- you can usually tell main street because it's wider for Fourth of July Day Parades and such- know what I mean?  So I say whatever looks right probably is!

how wide a normal two lane road should be

What part of town, residential, commercial, industrial? ? what era was the street constructed?? How much room do you have for a street??? ....DaveB

I make my roads 2" wide which

I make my roads 2" wide which means a lane width of about 13' in N scale.

a good guess

My highway lanes are 10-12 feet wide. Take 2 of your scale model cars or trucks , put them side by side and see what looks correct to you. Measure the width of the "road". Roads vary, main highways are wider, 2- lane county blacktops can be narrower. Gravel roads can be real wide to very narrow.  Don't forget to add a few feet for a shoulder, even they can be wide to narrow. It really depends on how much width you have to work with in the first place. If it is a narrow spot,, well, everything can be scaled back a bit and still look OK.  Here is what I do for city streets, I just assemble a bunch of scale cars and start lining them up, you know, 2 lanes for traffic, parking (angle or other). City streets can get pretty wide, so you might want to scale them back some. Years ago roads and shoulders were narrower than they are today. I hope this helps. Brian

FHA Chart of Roadway Widths

Here is a link to a chart published by Federal Highway Administration.  I assume the chart is for today's roadways, however I think the narrower widths listed in a range would be applicable to your time frame.

Roads and highways back then frequently had small or even no shoulders.  I remember as a kid riding down some highways that if you swerved off the road, you'd end up in the ditch.

Oversize

Always oversize your road/lane widths.   1-1/2 to 2 inches ( 12-15 foot in HO)  just looks better when a vehicle has visible space around it making the scene more realistic.  All to often modelers make the road widths the exact size of the vehicle, which does not look at all realistic.

One Way to save space and look good...

Depending on where your road is, a one way street can save some space.  The diorama I'm working on looked much too tight, ad certainly would have no on-street parking.  On some of thm, you do have to worry about mirrors of wider vehicles meeting.

Now,it's a one way street with on street parking, and has plenty of space. One way with on street parking needs much less space than 2-way.

Also, in some places, the roads are way pre DOT standards, with no practical way to widen them.  In New Hampshire's White Mountains, there's some adequate roads but with one lane bridges or underpasses.  Early bridges can be MUCH too solid to alte easily...

Joe, your road looks like some evil roads I've had to drive on--FAR too narrow for easy use--but there and in use anyway

Standard 1950 road

I agree with JamesS. IMHO a lot of layouts make there roads too narrow, which is completely understand when you are trying to selectively compress a scene.  A standard quality road of 1950 is going to be 5 inches wide in HO scale.  5 inches if you consider 6 ft shoulders on each side and two 12 ft lanes. 36ft = 4.95 inches.  Even if you reduce the shoulders down to 4 ft each with 10 ft lanes it is going to be 3.85 inches wide. So that is were I would be between 4 and 5 inches wide for HO.

Oversize

Hi James -

Richard Harden here. I lost contact with you after I built some structures for you awhile back. I was just looking for road width info for HO scale gravel/secondary roads and found this post from you. I wanted to get back in touch with you to see what is going on. I also wanted to let you know that I am still interested in build structures for other modelers. I think that when I changed my email address is when I lost contact with you. Have you got more done an your layout? How about a link or some pictures to see what is going on. Hope to here from you. My new address is richhard444@hotmail.com

Richard

Even today shoulders vary

Even today shoulders vary from 0 to 8 feet or more. Rural roads in the 1950's often did not have paved shoulders and had minimal gravel shoulders.  Haven't been on it in years, but looking at Google Earth a lot of Calif State Highway 17 has very minimal shoulders in many places.  Don't know if still the case but in the 1980's short  portions of the white edge line were actually painted outside the pavement  on dirt..  

Lane widths generally 9-12 feet.

In town  a minimal street will usually have two lanes for travel (one each direction) and  an approximately 8' wide parking lane for parallel parking, wider for 90 degree (about 18 feet for 90 degree)  or angled parking) with curbs and sidewalks on each side. But there are many exceptions both narrower and wider. Sidewalks might be a narrow as 2.5 feet' in residential area, but could be as much as 10 feet in business areas.

In general believe in making streets and roads on the narrow side do that they do not dominate the scene.

Need to look at the area you model,  Google Earth abd Bing are great resources for this.

Joe's Highway looks right for a narrow  California highway or county road (with minimal shoulder)  mid 1960's to the 2010 or so.  White edge lines were not adopted in California until the mid 1960's and probably about the same time in most states. .  More recently there has been a change in the standards for centerlines on Highways. The county roads I am familiar with still use the older standards.

Michaels road looks about right for a wider road with paved shoulders.  It needs a center line but no edge lines since it appears to be set in the 1950's.   Each travel lane and shoulders were and are usually paved separately so there likely be  a visible line between the travel lanes and in particular the travel lanes and the shoulders.

Another variation to consider for the 1950's, Traveled way on highways and some whole  streets  might be poured concrete slabs,  Paved shoulders on the highways - asphalt 

Another variation a road with a suicide lane on a straight stretch of road . 3 lanes wide, outside lanes for travel.. Center lane for passing in either direction.   Back in the mid 1950's my dad almost had a head-on on Highway 101. 

I tried to stay with what

I tried to stay with what looked right but fit into the space I had available in this town.

I'm not a nit picker or a river counter, but it it looks reasonably good, it works for me.

Links to California Highways

Links to California Highways and Public Works - Published by the State of California 1924-1967

http://www.americanroads.us/forum/index.php?topic=249.0

Funny you should mention CA 17....

That's the road I drive to my LHS. It has been upgraded (courtesy of an earthquake) to 4 lanes, 12' wide, with a concrete divider. In places the shoulder is less than 18" wide, with a drop off or a sheer cliff face on the other side. The center divider barely has room for a drainage grate between the lane and k-rail.

pqe

Source for Period Info on Highway Details

Here's a great source for details on signage for roads, grade crossings, etc. for various time periods:

https://ceprofs.civil.tamu.edu/ghawkins/MUTCD-History.htm

I don't know that you'll find anything about lane width, but that seems well adressed by previous posters.  I also model the late 50's and have found the info from this website very helpful.

Cheers,

Allen

Roads in the 50s

I remember quite well highways with little or no shoulder and narrow lanes from the '50s, even though I was fairly young. However, it will depend on where it is and what kind of traffic it is carrying. The ones I remember best are K-96 in Eastern Kansas (since replaced by US-400, thank God), US-81 south of Wichita, KS, and US-77 through Oklahoma, especially in the Arbuckle Mountains where is now a scenic drive. Even today there are single lane paved roads with little or no shoulder in the Nebraska Sand Hills. Check the road going north out of Ashby, NE on Google Earth. I spent a day driving some of those roads and there were long stretches where I honestly don't know what I would have done had there been any oncoming traffic, but there was none.