"Oil process surfacing"?

[NE2]

What does this mean on an old Colorado map? The types of road are, in order:
*unimproved
*graded
*surfaced [presumably this is gravel]
*oil process surfacing
*paved

Does this mean it was asphalt, or was there another type between gravel and asphalt?

[Big John]

I think that is where they sprayed oil then put gravel over it, in which the gravel hardens in the oil base.  Better than loose gravel but not as good as a regular surface.

[briantroutman]

I would assume it refers to some kind of a "tarmac" -type of treatment where a relatively coarse aggregate is mixed with petroleum as a binder, but not as thoroughly or finished as smoothly as modern asphalt.

I think you are right, though, in that "surfaced" would be gravel–and "graded" would be just that (graded), and "unimproved" would be simply cleared.

[Kniwt]

From the Pacific Rural Press, 10/29/1904:

How Oiling Began.–ln the beginning oil was used as a substitute for water to lay the dust of roads more cheaply. Its efficiency for this purpose was quickly recognized, and through the hardened and lasting surface obtained roadmakers were led to its use in making permanent road surfacing. It is along this latter line that such remarkable success has been attained.

http://cdnc.ucr.edu/cgi-bin/cdnc?a=d&d=PRP19041029.2.23.1#

[Scott5114]

I think that is where they sprayed oil then put gravel over it, in which the gravel hardens in the oil base.  Better than loose gravel but not as good as a regular surface.

Also known as "chipseal".

[roadman]

From the Pacific Rural Press, 10/29/1904:

How Oiling Began.—ln the beginning oil was used as a substitute for water to lay the dust of roads more cheaply. Its efficiency for this purpose was quickly recognized, and through the hardened and lasting surface obtained roadmakers were led to its use in making permanent road surfacing. It is along this latter line that such remarkable success has been attained.

http://cdnc.ucr.edu/cgi-bin/cdnc?a=d&d=PRP19041029.2.23.1#

And we found out how well THAT worked - http://en.wikipedia.org/wiki/Times_Beach,_Missouri

[Brandon]

From the Pacific Rural Press, 10/29/1904:

How Oiling Began.—ln the beginning oil was used as a substitute for water to lay the dust of roads more cheaply. Its efficiency for this purpose was quickly recognized, and through the hardened and lasting surface obtained roadmakers were led to its use in making permanent road surfacing. It is along this latter line that such remarkable success has been attained.

http://cdnc.ucr.edu/cgi-bin/cdnc?a=d&d=PRP19041029.2.23.1#

And we found out how well THAT worked - http://en.wikipedia.org/wiki/Times_Beach,_Missouri

Well, it works well when not mixed with dioxins.  It's still better, IMHO, to pave it outright.

[theline]

Having driven on many gravel roads and oil-treated roads in my younger days, I can confirm that the oil treatment was a big improvement. The oil made the driving smoother, allowed faster speeds and held down dust. Of course, paving was better when it could be afforded.

[cpzilliacus]

I think that is where they sprayed oil then put gravel over it, in which the gravel hardens in the oil base.  Better than loose gravel but not as good as a regular surface.

This was a very common practice on subdivision streets and other paved roads with low traffic volumes in my home county - Montgomery County, Maryland.

In Montgomery County, it worked like this - first, a water tank truck would come through and "wash" the pavement to be treated.  After the pavement dried (such operations were never done on rainy or cold days), an oil tank truck would put down a layer of hot oil (not quite as sticky as tar).  Right after the oil truck, a chip spreader would come along and put down a generous layer of pretty finely-milled rock chips.  After that, a pavement roller to get the chips to adhere (somewhat) to the oil. 

For several weeks after this treatment, the paved roads would have the "look and feel" of unpaved gravel roads, but eventually the chips would adhere, and some would get washed away in the rain.  After about a month, the oil truck would return and put down another layer over top of the chips to seal them in. 

I do not think the county does this any longer, because people complained that the loose chips damaged their cars.  The chips only did damage to cars that were going well over the 25 MPH speed limit.

[NE2]

So are you saying that "oil process" is the same as chipseal?

[J N Winkler]

So are you saying that "oil process" is the same as chipseal?

I don't think it is.  Oiling is a general term for using petroleum derivatives as a binder; chipsealing (surface dressing) is one specific application of the concept.  I have heard of other processes (notably within the context of early twentieth-century dust suppression trials) that involved spraying oil on the road surface and "working" it in somehow, without there necessarily being a subsequent application of rock chips.  An oiled surface might look and feel like gravel lightly wetted by a rainstorm, without having the same textural characteristics as chipseal.  (BTW, "waterbound macadam" is another term for what we call "gravel" and Australians call "unsealed.")

For Wikipedia articles and the like, it is enough to say a road has been oiled.  Cumbersome phrases like "[road] had 'oil process surfacing' applied" can be sacrificed without loss of clarity.  Single-sheet highway map legends from the 1920's and 1930's often provided "oiled" with a distinctive stroke as an alternative to "paved."