Earthworks Comps: accurate quantities

[Georgiou]

HI, Earthworks Comps: accurate quantities

 

I work as A project Engineer, however I'm also draft person which comes in handy.

 

Does anybody know the most effective way to calculate earthworks based on given cross sections for the land development industry.

 

i normally calculate earthworks by...

 

1. Drawing a ployline around the cut and fill areas

2. changing the scale to 1:1, so i get an accurate area

3. then multiplying distance between cross sections based on the average cut and fill areas within an excel spreadsheet.

 

Is there a more effective way to do this? Such as other programs or preferably a AutoCAD lisp?

 

Should i ask for additional information from the consultants or designers?

 

My goal is to determine the cut and fill volumes of a major subdivision.

 

Any suggestion would be appreciated.

 

Thanks

[BIGAL]

You have already answered your questions

 

Ask the engineers for volumes

 

Civil 3D etc can produce volumes in a couple of different ways (roads v's surfaces) I would expect all decent civil software will give you volumes.

 

A disclaimer though your volumes are only as good as the original survey, Aerial photos, hand sketched contours, actual field survey but at what spacing, how good is the final surface model has accurate breaklines been added.

 

No good using 10m cross sections if points are at 100m spacing how accurate is answer ?

 

Always do a rough check by hand often volume answers are not what you expect, I heard of a job design said had excess cut half way through ran out of fill expensive mistake.

 

As a software sales rep whilst demoing a real client job using our software found 1 pt with wrong height 30,000 cubic metres error 3.0 v's 30.0 customer bought me lunch.

[Georgiou]

i was simply illustrating what i already know,however I'm looking for more effective ways to do a quantity check accurately without being pedantic about it.

 

However the cross section are only between 5 -18m at the most. Additionally earthworks isn't an exact science, hence there is room for a 10% error margin.

 

The scope of works is typical your smaller type , approximately 6,000 - 20,000 square meters of area, excavation volume range between .2 to .7 of meter typically for roads, and about .1 to .6 for Lot ares.

 

Now, if i where to work on large Project area of 1,000,000 Square meters i might need to pay more attention to gradient changes, to insure an accuracy range of 85 to 90 percent. However, for the typical smaller jobs that really its much of an issue.

 

I'm simply after a quicker way to get cut and fill volumes whilst maintaining accuracy,

[Georgiou]

Does anybody have any further ideas/ advice?