I have my first 0.25' contour request, not sure if they have ever worked with that tight of a survey before. The sites are very steep, I may have to talk some sense into them before proceeding. This is just for driveway and site work of existing houses.
Contours
I've been asked to supply 0.25' contours when chasing water on a really flat surface, but I agree. In a steep area contours at that interval are overkill.
What fun. At least you aren't dealing with a topo that was shot with 2' interval precision but drawn by an engineer at .1' intervals. I recently did a paving overlay job like that. The engineer provided a 25' grid on a .1' contour interval map. When things didn't work he offered to provide a 10' grid. It took a couple weeks to prove to him that his original topo was shot at approximately 50' spacing and his grid was a figment of his imagination.
Maybe take a shot every 5 feet or so plus breaklines?
I love it when I get crazy requests.. just takes more time. I'll be glad to provide them with whatever they want, as long as they're paying for it.
I would not sign a .25' contour map . Nope
Why not?
Contours
I've been asked to supply 0.25' contours when chasing water on a really flat surface,
for flat parking hard surfaces, really helps show curb cuts, slight swells, that kinda thing; which when at 1' can get lost and really mess it up, but for steep ground, overkill.
This should dictate a very small grid when on natural terrain. Maybe a 25 foot grid would work on solid surfaces that are close to flat or somewhat uniformly sloped. My primary question to the client is "How is knowing this information going to alter what you are doing and impact which specific equipment that you plan to use for your work?" Laying out driveways is one thing. Laying out a landing strip at an airport is something else entirely.
better use the topo shoe.....don't want to push that prism pole into the ground at all. That could throw you off half a contour interval!
In NC topos are to meet the standard that the map must be accurate to half a contour over 90% of the site .
I'd make one up and send it to them to show what it would look like. A black blob of ink might change their minds
Contours
To clarify, I would only put 0.25' contours on something like a paved surface, as some have since mentioned.
I understand that, but if an area was paved, do you not think you could meet that standard? It would require a very tight grid (5'?) and running with a level, but I wouldn't have any problem doing one.
There are places .25' would be ridiculous (and useless) overkill. In others it wouldn't be good enough. When you survey a 40 that has less than a foot of relief over the entire site, you better find a way to tighten up. It's not really very difficult if the site conditions are right...
Well, they say to price it accordingly....
Yeh you could do that if its asphalt .
Since I am obligated to be accurate to plus or minus a 1/2 contour, there is no way I will stick my neck out to be accurate to 0.125 of a contour.
Sure, the software will do anything you tell it, but not worth the headache later.
Actually, I think its just stupid to even say you can do it with 100% confidence.
I say bail or teach some common sense.
Randy
It will look like a black solid hatch. Send it to them then rebill for re-doing it.
But eddy,
We could make the plat real big. 😉
The more decimal places the more dollar signs.
0.25' = $$$$$$$$$$
Let them know that your drawing scale will be 1ft = 1ft
Some requests are not practical.
I have had to edit and put grade slopes on topo maps in areas where the contours were so close together they plotted solid black.
😉