📊 Leveling Run

0/5 steps

Field Checklist (Supervisor-Free)

Instrument collimation known (Two Peg Test done if needed)Start BM RL confirmed; end BM/closure plan confirmedBalanced sight lengths (BS≈FS; within ~10 m)Turning points are hard/stable and clearly marked/witnessedStaff kept vertical (rod bubble) and readings to 0.001 mCall-and-repeat booking discipline followed (no memory booking)Arithmetic check done on-site before leaving (ΣBS−ΣFS = Last RL − First RL)

Stop Rules

Arithmetic check fails (ΣBS−ΣFS ≠ ΔRL)
Closing error exceeds allowable (ordinary: ±12√K mm) after re-checks
Turning point moved/unstable or staff point uncertain
Sight lengths badly unbalanced and cannot be corrected by repositioning

STEP 1

Plan the Run

STEP 1 — PLAN THE LEVELING RUN (FIELD SOP)
Goal: transfer RLs with a closed check and a passing arithmetic check.

Minimum equipment:
• Automatic/digital level + tripod (or total station in leveling mode)
• 2 staffs if possible (faster and safer), with rod bubbles
• Turning point plate (or solid peg) + chalk/marker
• Field book (or METARDU Field Mode) + backup pen

Before you start (trainee rule):
If instrument collimation is unknown OR the job is important → do a Two Peg Test first.
If Two Peg Test fails, STOP and rectify instrument (otherwise your RLs will be biased).

Plan your route:
1) Identify the starting benchmark (BM) with known RL.
2) Identify the closing BM (same BM loop closure is best) OR a second known BM.
3) Choose turning points (TPs):
   • every ~50–80 m (or as terrain demands)
   • hard/stable surface (concrete/rock/TP plate)
4) Compute the distance K (km) for tolerance checks.

Allowable misclosure (Basak):
• Ordinary leveling: ±12 √K mm
• Precise leveling:  ±6 √K mm

Booking template (copy into field book):
Station | BS | IS | FS | HI | RL | Remarks
Arithmetic check at end: ΣBS − ΣFS = Last RL − First RL

Trainee stop gate:
If you cannot close to a known RL (no end BM and no loop), STOP and redesign the run.

🔗Open METARDU Tool → Leveling

STEP 2

Set Up Level

STEP 2 — SET UP THE LEVEL (FIELD SOP)
Setup objective: balanced sights + stable instrument = reliable RL transfer.

Setup rules (Basak/standard practice):
• Set instrument roughly midway between BS and FS points (BS ≈ FS distance).
• Keep BS−FS distance difference within ~10 m (tighter for high precision).
• Avoid very long sights; keep individual sights reasonable for conditions (often ≤ 60–80 m; avoid >100 m if possible).
• Avoid long sights over hot surfaces (tar roads) to reduce shimmer/refraction.
• Tripod legs firm; instrument level stable through rotation.

Trainee workflow at each setup:
1) Choose a stable spot with clear sight to BS and FS.
2) Level the instrument properly.
3) Focus eyepiece (remove parallax) before reading staff.
4) Take BS first, then FS (consistent pattern reduces mistakes).

Trainee stop gate:
If you cannot balance sights due to terrain, you MUST note it and shorten sights; otherwise stop and reposition.

🔗Open METARDU Tool → Leveling

STEP 3

Take Readings

STEP 3 — TAKE READINGS (FIELD SOP)
At each instrument setup, you will record BS/IS/FS in a strict pattern.

Recommended reading pattern:
1) BS to known point or TP (call-and-repeat; book immediately).
2) Any IS readings (if you need intermediate points).
3) FS to next TP (call-and-repeat; book immediately).
4) Move instrument; the FS point becomes the next setup’s BS point.

Staff handling rules:
• Staff MUST be vertical (use rod bubble; rock the staff to find minimum reading if needed).
• Book to 0.001 m (3 decimals) consistently.
• Do not “correct” readings later — re-read in the moment if unsure.

Turning point (TP) rules:
• Use a TP plate or solid point (concrete/rock/firm peg).
• Mark and witness the TP location; do not change it between BS and FS.
• Never use loose stones, soft soil, or vibrating surfaces (vehicles/construction).

Quick sanity check at each setup:
• Rise/Fall = BS − FS (for that setup). If it looks unreasonable, re-check immediately.

Trainee stop gate:
If a reading was not written immediately (memory booking), STOP and re-read; do not guess.

🔗Open METARDU Tool → Leveling

STEP 4

Compute in METARDU

STEP 4 — COMPUTE + CHECK (METARDU SOP)
Enter the leveling data and DO NOT accept results until checks pass.

METARDU enforces Basak arithmetic check:
ΣBS − ΣFS MUST equal (Last RL − First RL).
If this fails: treat it as an error, not “close enough”.

If arithmetic check FAILS (blunder isolation):
1) Check for transcription errors (digit swap, wrong station line, wrong column).
2) Check that each TP appears twice correctly (FS then next BS).
3) Re-check staff units and decimal places.
4) If still failing, re-run the affected section in the field.

If arithmetic check PASSES:
• Check closing error against allowable tolerance (±12 √K mm ordinary).
• If out of tolerance: shorten sights, rebalance BS/FS, avoid heat shimmer, and re-run the section.

Trainee stop gate:
If arithmetic check fails OR misclosure exceeds allowable after re-checks, do not issue RLs.

🔗Open METARDU Tool → Leveling

STEP 5

Generate Report

STEP 5 — REPORT + HANDOVER (SOP)
Deliverables should show the checks clearly (so your work is defensible).

In METARDU:
→ Generate Report (PDF)

Minimum report contents:
• Start BM RL and closing BM RL (known + observed)
• RL table (HI and/or Rise & Fall)
• Arithmetic check statement and values (ΣBS, ΣFS, ΔRL)
• Closing error and allowable tolerance (±12 √K mm ordinary)
• If adjustment applied: method stated + corrected RLs
• Notes: date/time, crew, instrument ID, any unbalanced sights and why

Trainee rule:
Keep the raw booking. If RLs are challenged later, your raw notes are the evidence.

🔗Open METARDU Tool → Leveling