{"id":1497,"date":"2026-10-12T00:17:44","date_gmt":"2026-10-11T21:17:44","guid":{"rendered":"https:\/\/setaf2018.com\/?p=1497"},"modified":"2026-10-12T00:17:44","modified_gmt":"2026-10-11T21:17:44","slug":"geotechnical-drawings-quantity-takeoff","status":"publish","type":"post","link":"https:\/\/setaf2018.com\/en\/post\/geotechnical-drawings-quantity-takeoff\/","title":{"rendered":"Geotechnical Drawings: From Analysis Model to DWG and Quantities"},"content":{"rendered":"\n

Geotechnical drawings are the construction documents that turn a geotechnical design into something a contractor can build: wall layouts, sections through the support system, anchor and nail schedules, pile layouts, reinforcement details and the notes that govern sequence. They sit between the analysis and the site, and almost every error that reaches the field passes through them.<\/p>\n\n\n\n

\"Geotechnical<\/figure>\n\n\n\n

The analysis establishes what the structure has to be. The drawing establishes what will be built. In most offices those two documents are produced in different software, by different people, at different times, and the transfer between them is manual.<\/p>\n\n\n\n

That transfer is unglamorous. It is also where the expensive mistakes are made, because an error in transcription looks exactly like a correct drawing until someone builds it.<\/p>\n\n\n\n

Analysis errors are caught in review. Transcription errors are caught on site.<\/strong><\/p>\n\n\n\n

What Does a Geotechnical Drawing Set Contain?<\/h2>\n\n\n\n

The set varies with the work, but for excavation support and foundations the content is consistent.<\/p>\n\n\n\n

Drawing<\/th>What it fixes<\/th>Depends on<\/th><\/tr><\/thead>
General layout plan<\/td>Wall alignment, pile positions, plan geometry<\/td>Site boundary and structure layout<\/td><\/tr>
Support sections<\/td>Excavation depth, wall embedment, support levels<\/td>Analysis of each critical section<\/td><\/tr>
Anchor or nail schedule<\/td>Length, inclination, bond length, prestress, spacing<\/td>Capacity and internal stability checks<\/td><\/tr>
Strut and waler layout<\/td>Member sizes, levels, connection detail<\/td>Axial force, buckling and thermal load<\/td><\/tr>
Pile and cap details<\/td>Diameter, length, reinforcement, cap geometry<\/td>Axial and lateral capacity, TS 500 minimum steel<\/td><\/tr>
Construction sequence notes<\/td>Order of excavation and support installation<\/td>Staged analysis<\/td><\/tr>
Quantity schedule<\/td>Concrete, steel, drilling metres, grout<\/td>All of the above<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

The last two are the ones most often treated as an afterthought. Both are outputs of the analysis, not decorations added to it.<\/p>\n\n\n\n

Why Is the Transfer From Analysis to Drawing the Weak Point?<\/h2>\n\n\n\n

Because it is the only step in the chain with no automatic consistency check.<\/p>\n\n\n\n

Within the analysis, changing a soil parameter updates every dependent result. Within the drawing, changing a dimension updates the geometry. Between them, nothing propagates. An embedment depth revised from 4.5 m to 5.2 m in the calculation reaches the drawing only if a person remembers to change it, on every section where it appears.<\/p>\n\n\n\n

The failure mode is not carelessness. It is that a typical shoring design has several critical sections, each with its own wall length, support levels and member sizes, and each revision touches a subset of them. Keeping track of which subset is a bookkeeping problem, and bookkeeping problems scale badly.<\/p>\n\n\n\n

\"Geotechnical<\/figure>\n\n\n\n

What Changes When Drawings Come From the Analysis Model?<\/h2>\n\n\n\n

The geometry stops being re-entered.<\/p>\n\n\n\n

When the wall, the supports and the foundation elements are defined once in a three-dimensional model and the drawing is generated from that model, the drawing cannot disagree with the analysis, because it is a view of the same objects. A revised embedment appears in every section that shows it. A removed anchor row disappears from the schedule and from the quantity total at the same time.<\/p>\n\n\n\n

This is a narrower claim than it may appear. It does not make the design correct. It removes one specific class of error: the difference between what was analysed and what was drawn.<\/p>\n\n\n\n

How Is a Quantity Take-off Produced From the Same Model?<\/h2>\n\n\n\n

By measuring the objects that were analysed rather than the lines that were drawn.<\/p>\n\n\n\n

A bill of quantities assembled by scaling a drawing measures the drawing. A schedule generated from the model measures the design: pile lengths as designed, anchor drilling metres including bond and free length, concrete volumes from the actual member geometry, reinforcement from the detailing rules applied.<\/p>\n\n\n\n

The practical difference appears at revision. A manual take-off is a snapshot, valid for the drawing revision it was prepared from, and it silently becomes wrong when the drawing changes. A generated schedule is regenerated.<\/p>\n\n\n\n

Which Quantities Actually Matter on a Shoring Job?<\/h2>\n\n\n\n
Quantity<\/th>Why it drives cost<\/th><\/tr><\/thead>
Drilling metres<\/td>Rig time, the largest single variable on anchored walls<\/td><\/tr>
Concrete volume<\/td>Pile diameter and length, capping beam geometry<\/td><\/tr>
Reinforcement mass<\/td>Detailing rules and minimum steel, not just structural demand<\/td><\/tr>
Grout volume<\/td>Bond length and hole diameter, with overbreak allowance<\/td><\/tr>
Steel section mass<\/td>Strut and waler sizes from the staged analysis<\/td><\/tr>
Excavation volume<\/td>Stage by stage, not a single bulk figure<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Excavation volume deserves the note. Taken as one bulk figure it tells the contractor little, because the cost depends on how much can be removed before each support level goes in. Staged volumes come out of the staged analysis<\/a> rather than from the final section.<\/p>\n\n\n\n

What Happens When the Design Changes?<\/h2>\n\n\n\n

Every design changes. The question is what a change costs.<\/p>\n\n\n\n

A change in a linked model is an input edit followed by regeneration of the affected drawings and quantities. A change in a disconnected workflow is an input edit, a re-run, a manual comparison of old and new results, a set of drawing edits, a revision cloud, and a re-measured take-off. The second path is not only longer. It has more places to miss something.<\/p>\n\n\n\n

This is why the cost of a late change is a workflow property rather than a design property. The same revision is cheap in one office and expensive in another.<\/p>\n\n\n\n

Why Do the Drawing and the Report Disagree?<\/h2>\n\n\n\n

Three reasons, in descending order of frequency.<\/p>\n\n\n\n

The first is revision lag: the report was updated and the drawing was not, or the reverse. The second is rounding applied in the drawing for buildability, where a calculated 4.7 m embedment is drawn as 5.0 m, which is correct practice but has to be recorded, because the next person cannot tell a deliberate rounding from an error. The third is scope: the drawing shows a detail the analysis never covered, most often a connection, a transition between wall types, or a corner.<\/p>\n\n\n\n

None of the three is resolved by checking harder. They are resolved by removing the gap where they occur, and by writing down the roundings that remain.<\/p>\n\n\n\n

What Does Automatic Drawing Output Not Replace?<\/h2>\n\n\n\n

Judgement about buildability.<\/p>\n\n\n\n

A generated drawing is dimensionally consistent with the analysis. It does not know that the anchor it places passes through an adjacent property, that the strut level conflicts with the permanent slab, that the rig cannot reach the corner, or that the sequence assumed cannot be achieved with a single crane. Those are read from the drawing by an engineer who has built something.<\/p>\n\n\n\n

Nor does it replace detailing review. Reinforcement arrangement, cover, lap positions and connection details still require a designer to look at them. What generation removes is the copying, not the deciding.<\/p>\n\n\n\n

How Should the Drawing Set Be Checked Before Issue?<\/h2>\n\n\n\n

Against the analysis, not against the previous revision.<\/p>\n\n\n\n

The useful check is a short reconciliation: every governing dimension in the drawing traced to the calculation that produced it, and every deliberate rounding noted. On a shoring job that is wall length, embedment, support levels, anchor lengths and inclinations, member sizes, and the sequence notes. It takes an hour and it is the only check that catches transcription error, because reviewing a drawing against itself cannot.<\/p>\n\n\n\n

What Must the Drawing Say That the Calculation Does Not?<\/h2>\n\n\n\n

A calculation establishes capacity. A drawing has to establish buildability, and several of the things it must communicate never appear in the analysis output at all.<\/p>\n\n\n\n

Construction sequence is the first. A staged analysis assumes a particular order: excavate to a level, install the support, stress it, excavate again. If that order is not written on the drawing, the contractor is free to choose another, and the wall will have been analysed for a sequence it did not experience. The critical stage is rarely the final one, so an altered sequence is not a conservative deviation.<\/p>\n\n\n\n

Tolerances are the second. Pile verticality, anchor inclination and wall alignment all carry construction tolerances, and the analysis assumed nominal values. Where overlapping elements form a cut-off, or where an anchor has to clear a boundary, the tolerance has to be stated rather than implied, because a deviation that accumulates with depth turns a designed overlap into a gap.<\/p>\n\n\n\n

Prestress and testing requirements are the third. An anchor schedule that gives length and capacity without the lock-off load, the proof load and the acceptance criteria leaves the installer to choose them. The same applies to pile integrity testing and to the acceptance criteria for a ground improvement column.<\/p>\n\n\n\n

Monitoring and trigger levels are the fourth. Where the design predicts a wall deflection at serviceability, the drawing is where that prediction becomes an instruction: what is measured, how often, and at what reading work stops. A predicted deflection that never reaches the site is a number that cannot protect anything.<\/p>\n\n\n\n

A drawing that shows only geometry has communicated the result and withheld the reasoning that makes it safe.<\/strong><\/p>\n\n\n\n

Common Errors in Geotechnical Drawings and Quantities<\/h2>\n\n\n\n
Error<\/th>Consequence<\/th><\/tr><\/thead>
Drawing updated for one critical section but not the others<\/td>Built geometry differs from the analysed geometry<\/td><\/tr>
Buildability rounding applied without being recorded<\/td>Next reviewer cannot distinguish rounding from error<\/td><\/tr>
Quantities scaled from drawings rather than measured from the design<\/td>Take-off becomes wrong at the first revision<\/td><\/tr>
Excavation given as a single bulk volume<\/td>Contractor cannot price the sequence<\/td><\/tr>
Anchor schedule listing free length without bond length<\/td>Drilling metres understated<\/td><\/tr>
Construction sequence notes omitted from the drawing<\/td>Staged analysis assumptions not communicated to site<\/td><\/tr>
Reinforcement taken from structural demand only<\/td>Code minimum steel missed, quantity understated<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Where SETAF2018 Fits<\/h2>\n\n\n\n

SETAF2018 generates project drawings and quantity schedules from the same model that carries the analysis, which is the reason the two cannot drift apart.<\/p>\n\n\n\n

The excavation support system is built as a three-dimensional model: wall groups defining reinforced concrete or piled walls, anchors or soil nails at their design inclinations, and steel pipe, profile or concrete supports at their levels. Foundations are placed as rectangular, circular or polygonal elements with piles, micropiles, deep mixing or jet grout columns positioned individually or generated as a group. Analysis runs on sections through that model, stage by stage, following the construction sequence.<\/p>\n\n\n\n

Drawing output is produced as DWG project sheets with the project note generated automatically, and quantities as an XLSX schedule. Because both read the model, a revised embedment, an added anchor row or a changed pile layout appears in the drawing and in the schedule without a separate transfer step. Deep soil mixing carries its own cement and water quantity report for the mixing plant.<\/p>\n\n\n\n

The design behind the drawing follows the dependent pressures method with elasto-plastic Winkler springs, with the code checks applied through the Turkish excavation support regulation, TBDY 2018, EN 1997 and TS 500 minimum reinforcement. Calculation reports<\/a> show the equations behind each figure, so a dimension on a drawing can be traced to the check that produced it.<\/p>\n\n\n\n

Drawings, quantities and the wider excavation support<\/a> and project drawing<\/a> outputs come from one model, alongside the anchor<\/a>, soil nail<\/a> and soldier pile wall<\/a> design methods they are drawn from.<\/p>\n\n\n\n

Frequently Asked Questions<\/h2>\n\n\n\n

What are geotechnical drawings?<\/h3>\n\n\n\n

They are the construction documents that translate a geotechnical design into buildable information: wall and pile layouts, sections through the support system, anchor and nail schedules, strut and waler arrangements, reinforcement details and construction sequence notes. They are the form in which the design reaches the site.<\/p>\n\n\n\n

What is the difference between a geotechnical drawing and a quantity take-off?<\/h3>\n\n\n\n

The drawing fixes geometry and detailing; the take-off measures it. A quantity schedule lists drilling metres, concrete volumes, reinforcement mass, grout and steel sections. Both derive from the same design, which is why they should be produced from the same source rather than independently.<\/p>\n\n\n\n

Why do drawings and calculations disagree?<\/h3>\n\n\n\n

Usually revision lag, where one was updated and the other was not. The other two causes are buildability rounding applied in the drawing without being recorded, and details shown on the drawing that the analysis never covered, most often connections and transitions.<\/p>\n\n\n\n

Can drawings be generated automatically from a geotechnical model?<\/h3>\n\n\n\n

Yes, where the wall, supports and foundation elements are defined as objects in the model rather than drawn as lines. The drawing then becomes a view of the analysed geometry, and revisions propagate. What generation does not provide is buildability judgement or detailing review.<\/p>\n\n\n\n

How is a bill of quantities produced for a shoring job?<\/h3>\n\n\n\n

By measuring the designed elements: drilling metres including bond and free length, concrete volume from member geometry, reinforcement mass from the detailing rules applied, grout volume with an overbreak allowance, steel section mass from the staged analysis, and excavation volume stage by stage rather than as one bulk figure.<\/p>\n\n\n\n

Which quantity has the largest effect on cost?<\/h3>\n\n\n\n

Drilling metres on anchored and piled walls, because they govern rig time. Reinforcement mass is the one most often understated, since code minimum steel can exceed structural demand and is easy to omit when quantities are taken from structural results alone.<\/p>\n\n\n\n

Should rounding in drawings be recorded?<\/h3>\n\n\n\n

Yes. Rounding a calculated 4.7 m embedment to 5.0 m for buildability is correct practice, but an unrecorded rounding is indistinguishable from a transcription error to the next person who checks the set, and it invites a correction that reverses a deliberate decision.<\/p>\n\n\n\n

How should a drawing set be checked before issue?<\/h3>\n\n\n\n

Against the analysis rather than against the previous revision. Every governing dimension traced to the calculation that produced it, and every deliberate rounding noted. Reviewing a drawing against itself cannot detect a transcription error, because the drawing is internally consistent either way.<\/p>\n\n\n\n\n