> And that engineering company just dreamed this arcane rule up because they got burned by getting some bad topo from somebody.
I doubt that... I just sounds like somebody living in the past. I actually remember doing topo surveys that way, where we would use a transit and chain to lay out a 50' grid in a field, then use the automatic level to shoot the elevations at each point.
Haven't done a topo survey like that since the mid-80's, though...
If the accuracy of "laying out the grid" is not specified; then pacing is an acceptable way of laying out the grid.
Time to promote the capital S in surveyor.
A request for grid only as instructed requires your professional input to advise the client that there are pitfall in the request as changes of grade do not fall on grid corners. Explain also that the mathematical assumption in making a model for contours assumes between any two points a constant grade and therefore more important to locate change of grade points. Also explain that today's surveying equipment negates the need to set out the traditional grid.
That all said if the client insists on grid point levels because they have state of ark methods of handling the data.
The work around is to level the site, create a model , superimpose a grid and get the program to interpolate levels at each grid intersection point.
Result will be more than adequate for the client if you have created a good DTM.
RADU
Bruce Gidday from DU
I noticed that U have not added a public email address
If U don't want to publicise it then drop me an email...
RADU
50' Grid Means 50' Grid, Topo Means Breaklines
You need to do both.
BTW, McDonald's specification was a 20' grid.
Paul in PA
Engineer wanted a 20' grid on a site that was nothing but pea gravel (Gambell, St Lawrence Island) that the only relief was the tire tracks from a 966 loader made when the old fuel tanks were moved. He went to a meeting and I jumped on the D-8 and smoothed it out. He went for a 100' grid!:-D
Sometimes they just aren't so sure of what they want!
-JD-
Bruce Gidday from DU
I forgot to check the box. Should be okay now.