A drainage layout, a scale rule and two days
A tender arrives for groundworks on a housing phase: foul and surface water layouts, manhole schedules, road and plot levels, and a tight return date. Your estimator prints the drainage layout, measures each run between manholes, works out the depth from cover and invert levels, puts each run in a depth band, counts manholes by size and depth, and counts plot connections. Then it all goes into the pricing spreadsheet.
It takes days. There are three other tenders waiting. And one misread invert level puts a run in the wrong depth band.
Why drainage take-off is so slow
The information is on the drawings, but not in a form a spreadsheet can use. Lengths are drawn, not tabulated. Depths have to be worked out from two levels at each end. Manhole schedules help but are sometimes missing or out of step with the layout. Every tender, the same measuring is done again from scratch.
- Run lengths are measured from drawings by hand or with PDF tools.
- Depth bands are worked out from cover and invert levels.
- Manhole schedules do not always match the layout.
- Quantities are typed into the pricing sheet manually.
- Revised drawings mean measuring again.
What slow take-off costs
Estimator time that limits how many tenders you can price properly. Errors in depth bands that change the price of a run. Tenders priced in a rush or declined. And revisions from the engineer, which are common in groundworks, that mean doing a large part of the take-off again.
Assisted take-off we build
- Drainage layouts and manhole schedules, as PDF or CAD files, are loaded for the tender.
- Runs are identified between manholes, with lengths measured from the drawing scale or CAD geometry.
- Cover and invert levels are read from labels or schedules, and depths calculated at each end.
- Each run is put in your depth bands, with pipe size and material where stated.
- Manholes are listed by type, size and depth, and plot connections and gullies are counted.
- The estimator reviews each item on screen against the drawing, corrects anything misread, and marks items the drawing does not make clear.
- Quantities export to your pricing spreadsheet or estimating system. When revised drawings arrive, changed runs are highlighted.
| Take-off item | Read from | Estimator's role |
|---|---|---|
| Run lengths | Drawing scale or CAD | Check against drawing |
| Depths and bands | Cover and invert levels | Check anything unclear |
| Manholes | Layout and schedule | Confirm types and sizes |
| Connections and gullies | Layout | Check counts |
| Revisions | New drawing compared with old | Review changed items |
Take-off accuracy depends on the quality of the drawings. Every item is checked by your estimator; nothing goes into a price unreviewed.
More tenders priced properly
Estimators spend their time checking and pricing rather than measuring. Depth bands are calculated consistently. Revisions show what changed, so re-pricing is quick. You can price more of the tenders you want, and each one with more care. And the take-off is saved with the tender, so if you win it, the site team starts with the same quantities.
It also helps when the engineer issues a revised layout halfway through the tender period, which happens often enough in groundworks to plan for. The changed runs are listed, so your estimator can see at once whether the revision moves the price or just tidies a few levels, and the tender goes back with the right drawings referenced.
Is your drainage take-off like this?
- Drainage runs are measured by hand for every tender.
- Depth bands are worked out one run at a time.
- Quantities are typed into the pricing sheet.
- Revised drawings mean starting again.
- You decline tenders because estimating is full.