Interrupted Dashed Lines
Posted 31 March 2009 - 01:58 PM
I have been reviewing an old topography map of a piece of property in the North Eastern united states that was drawn in 1939.
This map has a curvy twin dashed line that represents a road, however the twin dashed lines are interrupted. So in layman's terms there is a stretch of twin dashed lines, then a gap, then more twin dashed lines, then another gap, and so on. There is no additional marking when the dashed lines stop, just a blank space until the dashed lines start again.
I was wondering what this indicates as I was unable to get an symbol list or legend that showed what a gap in a road means.
Your expert advice would be much appreciated.
Also, if I'm posting this in the wrong place, please let me know so I can correct it.
Posted 31 March 2009 - 03:52 PM
Sounds like a 4wd jeep road to me.
Does it look like this?
Picture_128.png 4.77KB 60 downloads
It could also be a tunnel...
Thanks for the quick response.
It's sorta like that. I looked up the USGS symbols and it matches the Undeveloped Road symbol. It's basically a strip like the picture you linked, followed by blank space and then it starts up again. It's not just a dashed line, but a real gap in the dashed lines followed by more. It also doesn't have a designation of a tunnel and there is no tunnel there in the actual area.
We figure its where the surveyor could not establish a road, say overgrown with grass or whatever, but I wanted to be certain. From what I gathered an Undeveloped Road means any unpaved road that is considered fair terrain that is passable in good weather, so I could see parts of it being overgrown to the point where it was not obvious that it was a road. I just want to make sure that that's what that gap indicates.
Posted 02 April 2009 - 12:32 PM
Can you post a small scan so we can see the context?
Chances are good that the sheet is already up on the web at http://docs.unh.edu/...pos/nhtopos.htm
I will see if I can scan it in tomorrow. My boss has it with him at a deposition. It's a terrible black and white (not grayscale) copy though, but hopefully it'll be clear enough.
Thanks again for the help.
Posted 02 April 2009 - 04:02 PM
One might assume it is indeed some sort of wagon track or other logging or agricultural road, perhaps with indeterminate boundaries (wider parts on soft ground, fainter on hard patches). However, although one might think that such a symbol might suggest something of the nature of the track, it could also be that the draftsman was using a template to draw his dashes and / or didn't feel he needed to do quite so much inking for this particular feature: he shows it is there and that is enough.
I seem to remember pulling that trick when drawing such maps myself; do a section as long as my parallel dash template and then shift a bit further down. You concentrate on the complex bits, but otherwise avoid having to make smooth dash transitions between different segments.
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