When did streets begin to be constructed with “crowns” in the middle? Is this a more recent phenomenon, or has it been around for a while? Thanks.
Tom
I’m pretty sure the Romans had crowned streets.
Dave H.
Yes. IIRC the word “highway” was coined to describe the Roman-built roads in Britain because they were built up higher than the surrounding ground to allow drainage, which would include being crowned to allow water to run off to the sides.
So, a state route (SR) asphalt road in the 20s, 30s, or 40s would not look out of place with a crown to it?
Tom
No. Actually it would look out of place without it.
Dave H.
Thanks, Dave. Thank you, too, Styx.
Tom
In the 1920’s, or the 20’s (i.e. Roman times) it would work !!
BTW it’s Stix not Styx. [(-D]
So, okay, I’ll be the one to ask first. Other than out of curiosity, why did you want to know this? Are you considering actually modelling a road with a crown down the center? I don’t know what the actual crown would be for a typical 2-lane road, but aside from the difficulty of modelling the road, will the finished product satisfy the two-foot rule? You know…if it’s more than two feet away on the layout, no one will see the detail anyway!
Oops! Sorry, Stix. [:I] Yes, that would be the 1920s. Ben Hur just looked a little out of place to include him on the layout. [swg]
Tom
maxman,
A perfectly reasonable inquiry. I posed the question because I am constructing a road on my early 40s (for Stix that would be 1940s [:)]) New York Central layout. The road will be made out of 3-1/8" wide x 1/16" thick cork sheeting. (That’s 22.7’ in HO scale - slightly narrower than a standard 24’ wide road but close enough.)
While not essential, I was just curious whether or not a slight crown to the road would enhance it’s realism. I’ve already superelevated the curves of my mainline slightly and there is a small but noticable difference in the appearance of the train as it navigates around the track. My thought is: Before tacking down the road, adhere a thin strip of balsa wood (thickness to be determined) along the bottom side of the cork sheeting to create the crown in the middle of the road.
It may be that it’s more trouble than it’s worth. Even so, I thought it would be fun to experiment to see whether it’s worth the extra effort or not.
Tom
And a perfectly reasonable answer to my question. But if I may offer a few thoughts? I understand the track superelevation and how the appearance of the train tilting through the curve looks impressive. But don’t forget that the height of the cars accentuates the amount of elevation that you added under the track. I’m not sure that this will be as visible with stationary objects on a road unless the amount is exaggerated to be more than what is prototypical. And I don’t really know what the amount of crown should be. I looked for this information but didn’t really have any luck finding it. I’m sure someone will tell us.
Anyway, when you first described doing this, I envisioned a plaster or joint compound affair where you made a curved screed or scraper to give you the crown shape. I don’t think your cork idea will work. I understand the idea of the piece of plastic or stripwood down the center to get the height, but how will you get the cork to conform to or retain a curved surface? I’m not sure, but I don’t think a crowned road is really like a flattened out peaked roof with a ridge down the center and a constant slope to each side. I think it’s more like a rounded shape. But I’m sure that there must be a website somewhere that shows a road cross-section. Inquiring minds want to know!
maxman,
Good points and thanks for expressing them. I also had concerns whether or not I could achieve what I wanted with the cork sheeting. I guess that’s what I’ll have to experiment with and try to see if the results are satisfactory or not.
And I also tried searching the Net for a cross-sectional view of a road last night but wasn’t able to find anything either.
Tom
In addition to crowning, road curves have been superelevated on those routes with higher speed limits at least since the 1930’s - a lot of them rebuilt as WPA projects.
As for cross-section, the surface crowning is set clear down at compacted subgrade level. The various layers of paving material are uniform thickness.
Modern concrete roads are more ‘tilted’ than crowned. The pavement slopes, but in a straight line when viewed in cross-section.
Chuck (modeling Central Japan in September, 1964)
Here is some proto information from the dirt road thread, see the details given at the bottom of the thread:
Not the best picture, but I added a crown to this street by placing a roughly 1/2" wide strip of .060" styrene beneath the centre of the .060" sheet styrene “pavement”. The roadway material extends beneath the sidewalks (more .060" sheet) and is fastened to the plywood layout top with contact cement. To get a good bond between the wood and styrene, I first “prepped” the contact areas of the styrene with lacquer thinner, then applied the contact cement as usual. I think that the crown looks good, but it’s not something that’s readily apparent.
If you’re making your roads using some type of plaster, you could make a “form” that could be dragged along the length of the top of the still-wet plaster, then hand-fill later to a flat profile at railway crossings.
Wayne
Maxman: “…I don’t really know what the amount of crown should be. I looked for this information but didn’t really have any luck finding it. I’m sure someone will tell us. And I don’t really know what the amount of crown should be. I looked for this information but didn’t really have any luck finding it. I’m sure someone will tell us.” …“But I’m sure that there must be a website somewhere that shows a road cross-section. Inquiring minds want to know!”
tstage: “And I also tried searching the Net for a cross-sectional view of a road last night but wasn’t able to find anything either.”
SINCE you asked, and SINCE this is a “prototype information” forum, I will give you my two cents worth. It is two cents worth in 1930-something pennies, which are worth more than 2008 pennies. Especially for a steam era or transition-era period modeling question.
When I have a little extra time in a small town, I wander into local public libraries to see if they have any interesting books I have not seen. Often, small towns down have a big library budget. They have books that were donated, often out of date and obsolete. Just what I am looking for. In Aransas Pass, Texas public library, I found a 1937 college engineering textbook on “modern” highway design, and copied 12 or 15 pages from it. It shows a crown for a concrete paved roadway with a 1/4" rise in each one foot from pavement edge to center line. In this case, the entire paved width was 20 feet wide, so each lane was 10 feet from edge to center. That means the crown would rise 2 1/2" above the outside edge of the pavement.
The same diagrams showed the shoulder of the road 6 tp 10 feet wide with a 1" to 1 foot slope.
For a typical clay-sand road, or gravel road, diagrams showed 1/2" inch crown p
Kevin, Wayne, and Ken;
Thanks! Good stuff! [:)][tup] More things to contemplate…
Tom
Wayne,
Your photo certainly argues for a crown. The cars gently tipping to the side look “right”. My roadways will now definitely have crowns. It sounds like you are happy with the technique you shared. Would you make any changes in it for upcoming projects?
Good work,
Ed
From the CALTRANS (California DOT) Highway Design Manual
The Manual is available On Line at www.dot.ca.gov
301.2 Cross Slopes
(1) General. The purpose of sloping on roadway cross sections is to provide a mechanism to direct water (usually from precipitation) off the traveled way. Undesirable accumulations of water can lead to hydroplaning or other problems which can increase accident potential. See Topics 831 and 833 for hydroplaning considerations.
(2) Standards.
(a) The standard cross slope to be used for new construction on the traveled way for all types of surfaces shall be 2%.
(b) For resurfacing or widening when necessary to match existing cross slopes, the minimum shall be 1.5% and the maximum shall be 3 percent. However, the cross slope on 2-lane and multilane AC highways should be increased to 2% if the cost is reasonable.
(c) On unpaved roadway surfaces, including gravel and penetration treated earth, the cross slope shall be 2.5% to 5.0%.
Thanks, Ed. That little dead-end street is the only one on which I used this technique. All of the other paved streets in this town are wider and fairly short, ending at the backdrop and crossed by several tracks, so there’s not enough room to provide a transition to a flat cross-section at the tracks.
This one, also dead-ending at the tracks, would be suitable, but the road surface is only .010" thick - I installed the building and sidewalks before the road surface,[banghead] and I’m afraid that the thinner material would sag if crowned in the same manner.
The rest of the roads on the layout are done with plaster, and none of them crowned:
Wayne