Circular 20/1966 & CMR 2017 – DGMS Survey Limits of Error: 100 Solved MCQs for Coal Mines Regulations Exam

📘 DGMS Notification (G.S.R. 973(E), Dhanbad, 1st Oct 2018) Issued under Reg. 64(3), Coal Mines Regulations, 2017
By Prasanta Kumar Sarkar, DGMS & Chief Inspector of Mines

🔹 1.0 Plans 📍 Accuracy with Survey of India National Grid

All mine boundaries, shafts, reference points & features → must match SOI National Grid ✅

Within limits of survey & plotting error.

📏 Plotting Errors:

🗺️ Plan scale 1:2000 → 50 cm error allowed

🗺️ Plan scale 1:1000 → 25 cm error allowed

🔹 2.0 Surface Surveys ⛰️ 2.1 Triangulation Stations

Position of triangulation stations = within 1/5000th of horizontal distance from point of origin.

📐 2.2 Traverses Every traverse → must close polygonally 🔄

(i) Angular error ≤ 30√n sec (n = no. of stations incl. start & end).

(ii) Closure error (by coordinates) ≤ 1/3000th of traverse length.

🔹 3.0 Underground Surveys ⚙️ 3.1 Instruments

Theodolite (least count ≤ 20″).

Measurements with steel tape ≥ 30 m.

📐 3.2 Angular Error (Closed Traverse)

Formula: (20 + x)√n sec

x = 10 sec or instrument LC (whichever higher).

n = no. of observing stations.

📏 3.3 Error of Closure (Closed Traverse)

≤ 1/2500th of traverse length.

🔓 3.4 Error of Closure (Open Traverse)

Traverse starts & ends at known reference points but not closed polygonally.

Error ≤ 1/1500th of traverse length.

🛠️ 3.5 Subsidiary Surveys

For face/goaf/road junction.

Closure error ≤ 1/500th of traverse length.

🔍 3.6 Checking Subsidiary Surveys

If check survey stations not possible.

Difference between two surveys ≤ 3 m.

🔹 4.0 Correlations 🔗 By Shaft Wires:

Difference in azimuth ≤ 2′ arc

🧭 By Magnetic Observations:

Difference in azimuth ≤ 2′ arc

🚪 By Direct Connection (adits/inclines):

Difference in azimuth ≤ 1′ arc

🔹 5.0 Levels 📏 Surface Bench Marks (BM):

Levelling between SOI or Railway BMs.

Error ≤ 2 cm/km

⛏️ Shaft Inset Bench Marks:

Measurements must agree within 1/5000th.

🚇 Underground Levelling:

Closure error ≤ 1/2500th of inclined length.

🪨 Subsidiary Levelling (faces/goaf):

Difference ≤ 50 cm.

📊 Summary Table – Limits of Error

📝 Survey Type ✅ Permissible Error

Plans (Plotting)

Scale 1:2000 ≤ 50 cm

Scale 1:1000 ≤ 25 cm

Surface Surveys

Triangulation stations ≤ 1/5000th distance

Traverse angular error ≤ 30√n sec

Traverse closure ≤ 1/3000th length

Underground Surveys

Angular error (closed) (20+x)√n sec

Closure error (closed) ≤ 1/2500th length

Closure error (open) ≤ 1/1500th length

Subsidiary survey ≤ 1/500th length

Difference in 2 surveys ≤ 3 m

Correlations

Shaft wires ≤ 2′ arc

Magnetic observations ≤ 2′ arc

Direct connection ≤ 1′ arc

Levels

Surface BM levelling ≤ 2 cm/km

Shaft inset BM Agree within 1/5000th

Underground levelling closure ≤ 1/2500th length

Subsidiary levelling ≤ 50 cm

🎯 Quick Memory Tricks

📝 Survey Type	✅ Permissible Error
Plans (Plotting)
Scale 1:2000	≤ 50 cm
Scale 1:1000	≤ 25 cm
Surface Surveys
Triangulation stations	≤ 1/5000th distance
Traverse angular error	≤ 30√n sec
Traverse closure	≤ 1/3000th length
Underground Surveys
Angular error (closed)	(20+x)√n sec
Closure error (closed)	≤ 1/2500th length
Closure error (open)	≤ 1/1500th length
Subsidiary survey	≤ 1/500th length
Difference in 2 surveys	≤ 3 m
Correlations
Shaft wires	≤ 2′ arc
Magnetic observations	≤ 2′ arc
Direct connection	≤ 1′ arc
Levels
Surface BM levelling	≤ 2 cm/km
Shaft inset BM	Agree within 1/5000th
Underground levelling closure	≤ 1/2500th length
Subsidiary levelling	≤ 50 cm

1️⃣ Plans – 2000 → 50 cm, 1000 → 25 cm 📏
2️⃣ Surface traverse – angular = 30√n, closure = 1/3000 📐
3️⃣ Underground traverse – angular = (20+x)√n, closure = 1/2500 ⛏️
4️⃣ Open traverse – 1/1500 🚪
5️⃣ Subsidiary surveys – 1/500 or 3 m 🪨
6️⃣ Correlations – Shaft/Magnetic = 2′, Direct = 1′ 🔗
7️⃣ Levels – Surface = 2 cm/km, Inset = 1/5000, Inbye = 1/2500, Subsidiary = 50 cm 🌍

📝 50 MCQs – DGMS Notification (Limits of Error, 2018)

Q1. According to DGMS Notification (2018), the maximum plotting error allowed for a mine plan prepared on the scale of 1:2000 is: A. 25 cm
B. 50 cm
C. 100 cm
D. 75 cm
E. 20 cm

✅ Answer: B. 50 cm
Explanation: For scale 1:2000, permissible error = 50 cm. For 1:1000, error = 25 cm.

Q2. In case of mine plans on the scale of 1:1000, the maximum plotting error must not exceed: A. 50 cm
B. 25 cm
C. 10 cm
D. 1/2000th of scale
E. 100 cm

✅ Answer: B. 25 cm
Explanation: Notification specifies plotting error ≤ 25 cm for scale 1:1000.

Q3. Triangulation station positions must be within what error limit from the point of origin? A. 1/2000th of distance
B. 1/2500th of distance
C. 1/5000th of distance
D. 1/1500th of distance
E. 2 cm/km

✅ Answer: C. 1/5000th of distance
Explanation: Surface triangulation error must not exceed 1/5000th of horizontal distance.

Q4. The formula for total angular error in a surface traverse is: A. (20+x)√n seconds
B. 1/2500th of traverse length
C. 30√n seconds
D. 1/1500th of traverse length
E. 2 minutes of arc

✅ Answer: C. 30√n seconds
Explanation: Surface traverse angular error = 30√n seconds, where n = no. of observing stations.

Q5. The error of closure for a surface traverse after adjustment must not exceed: A. 1/2500th of traverse length
B. 1/1500th of traverse length
C. 1/3000th of traverse length
D. 50 cm
E. 1/5000th of traverse length

✅ Answer: C. 1/3000th of traverse length
Explanation: As per notification, surface traverse closure error = ≤ 1/3000th.

Q6. For underground main road traverses, which instrument is mandatory? A. Compass (LC = 1°)
B. Dumpy Level
C. Theodolite (LC ≤ 20″)
D. Total Station
E. Plane Table

✅ Answer: C. Theodolite (LC ≤ 20″)
Explanation: Regulation specifies theodolite with least count ≤ 20 seconds.

Q7. In underground surveys, the formula for angular error of a closed traverse is: A. 30√n seconds
B. (20+x)√n seconds
C. 1/1500th of traverse length
D. 1/2500th of traverse length
E. 1/500th of traverse length

✅ Answer: B. (20+x)√n seconds
Explanation: Where x = 10″ or least count of instrument (whichever higher).

Q8. The closure error for underground closed traverse must not exceed: A. 1/2500th of traverse length
B. 1/3000th of traverse length
C. 1/1500th of traverse length
D. 3 m
E. 2 cm/km

✅ Answer: A. 1/2500th of traverse length
Explanation: Underground closed traverse → error ≤ 1/2500th.

Q9. For an underground open traverse, the error of closure allowed is: A. 1/5000th
B. 1/2500th
C. 1/3000th
D. 1/1500th
E. 2 minutes of arc

✅ Answer: D. 1/1500th
Explanation: Open traverse = ≤ 1/1500th of length.

Q10. The permissible error of closure in a subsidiary underground survey is: A. 1/2500th
B. 1/3000th
C. 1/500th
D. 2 minutes of arc
E. 50 cm

✅ Answer: C. 1/500th
Explanation: Subsidiary surveys = ≤ 1/500th of traverse length.

Q11. If two independent subsidiary surveys are compared, the difference must not exceed: A. 1 m
B. 2 m
C. 3 m
D. 5 m
E. 50 cm

✅ Answer: C. 3 m
Explanation: Difference ≤ 3 m.

Q12. Correlation of surface and underground workings by shaft wires is within limit if difference in azimuth is not more than: A. 1 minute of arc
B. 2 minutes of arc
C. 5 minutes of arc
D. 30 seconds
E. 20+x seconds

✅ Answer: B. 2 minutes of arc
Explanation: Shaft wire correlation limit = ≤ 2′ arc.

Q13. Correlation by magnetic observation is acceptable if difference in azimuth is ≤: A. 1′
B. 2′
C. 3′
D. 30″
E. 5′

✅ Answer: B. 2′
Explanation: Same as shaft wires = ≤ 2 minutes of arc.

Q14. Correlation by direct connection (adits/inclines) is acceptable if difference in azimuth is ≤: A. 1′
B. 2′
C. 30″
D. 3′
E. 20+x seconds

✅ Answer: A. 1′
Explanation: Direct connection correlation = ≤ 1 minute of arc.

Q15. The levelling error allowed for surface mine benchmarks is: A. 1/1500th of length
B. 2 cm/km
C. 50 cm
D. 1/2500th
E. 1/5000th

✅ Answer: B. 2 cm/km
Explanation: Surface levelling error limit = 2 cm per km.

Q16. Inset benchmarks (shaft measurements) must agree within: A. 2 cm/km
B. 1/1500th
C. 1/2500th
D. 1/5000th
E. 3 m

✅ Answer: D. 1/5000th
Explanation: Inset BM error = ≤ 1/5000th.

Q17. Underground levelling (between inbye BMs) must close within: A. 1/1500th
B. 1/2500th
C. 1/5000th
D. 50 cm
E. 2 cm/km

✅ Answer: B. 1/2500th
Explanation: Underground levelling error limit = 1/2500th of inclined length.

Q18. Subsidiary levelling for face/goaf points must not differ by more than: A. 1 m
B. 2 cm/km
C. 50 cm
D. 25 cm
E. 3 m

✅ Answer: C. 50 cm
Explanation: Difference ≤ 50 cm.

Q19. Who issued the notification on survey limits of error under CMR 2017? A. Ministry of Coal
B. DGMS (P.K. Sarkar)
C. Survey of India
D. Coal India Ltd.
E. Indian Bureau of Mines

✅ Answer: B. DGMS (P.K. Sarkar)
Explanation: Issued by Chief Inspector of Mines, Prasanta Kumar Sarkar.

Q20. Under which regulation of CMR 2017 is this notification issued? A. Reg. 61(2)
B. Reg. 64(3)
C. Reg. 54(2)
D. Reg. 72(1)
E. Reg. 100(1)

✅ Answer: B. Reg. 64(3)
Explanation: Notification was issued under Regulation 64(3).

Q21. For a surface traverse with 9 stations, the maximum total angular error allowed is: A. 30√9 = 90 seconds
B. 30√9 = 270 seconds
C. 30√9 = 900 seconds
D. 20√9 = 180 seconds
E. 10√9 = 90 seconds

✅ Answer: B. 270 seconds
Explanation: Formula = 30√n. For n=9 → 30×3 = 90. But remember, n includes initial + closing stations, so 9 obs = 9√ = 3 → 30×3 = 90″. Wait correction: If n=9, √n=3, so error=90″. Correct option is A (90 seconds).

Q22. For an underground closed traverse with 16 stations and instrument LC=20″, maximum angular error allowed is: A. (20+10)√16 = 30×4 = 120 sec
B. (20+20)√16 = 40×4 = 160 sec
C. (20+20)√10 = 40×3.16 = 126 sec
D. (20+10)√10 = 30×3.16 = 95 sec
E. 30√n = 120 sec

✅ Answer: B. 160 sec
Explanation: Formula = (20+x)√n. Here x=20 (LC). So (20+20)√16 = 40×4=160″.

Q23. If an underground open traverse of 1500 m length is made, maximum error allowed in closure is: A. 0.5 m
B. 1.0 m
C. 1.5 m
D. 2.0 m
E. 3.0 m

✅ Answer: C. 1.0 m
Explanation: Error ≤ 1/1500 of length. For 1500 m → 1 m.

Q24. For a closed underground traverse of 2500 m length, max permissible error of closure is: A. 1.0 m
B. 1.5 m
C. 2.0 m
D. 3.0 m
E. 0.5 m

✅ Answer: A. 1.0 m
Explanation: Error ≤ 1/2500 of length. For 2500 m → 1 m.

Q25. For a subsidiary underground survey of 1000 m, permissible plotting error is: A. 1 m
B. 2 m
C. 3 m
D. 5 m
E. 10 m

✅ Answer: B. 2 m
Explanation: Subsidiary survey error ≤ 1/500th of length. For 1000 m → 2 m.

Q26. If two independent subsidiary surveys differ by more than 3 m, the survey is considered: A. Accurate
B. Within limit
C. Out of permissible limit
D. Correlated
E. Triangulated

✅ Answer: C. Out of permissible limit
Explanation: Max difference allowed = 3 m.

Q27. Which method of correlation is the most precise according to DGMS Notification? A. By magnetic observations
B. By shaft wires
C. By direct connection (adits/inclines)
D. By subsidiary survey
E. By triangulation

✅ Answer: C. By direct connection (adits/inclines)
Explanation: Direct connection limit = 1′ arc, which is tighter than shaft/magnetic (2′ arc).

Q28. The difference in azimuth between two independent shaft wire observations must not exceed: A. 1′
B. 2′
C. 30″
D. 3′
E. 20″

✅ Answer: B. 2′
Explanation: Shaft wire correlation error = ≤ 2 minutes of arc.

Q29. Levelling for surface mine benchmarks must start and close upon: A. Any building corner points
B. Bench marks established by DGMS
C. Survey of India or Railway benchmarks
D. Mine manager’s reference stations
E. Any triangulation pillar

✅ Answer: C. Survey of India or Railway benchmarks
Explanation: Notification specifies SOI or Railway BMs.

Q30. Error limit for surface benchmark levelling per km is: A. 1 cm/km
B. 2 cm/km
C. 3 cm/km
D. 5 cm/km
E. 10 cm/km

✅ Answer: B. 2 cm/km
Explanation: Surface levelling permissible error = ≤ 2 cm per km.

Q31. If two shaft inset BM measurements disagree beyond the limit, the error exceeds: A. 1/1500
B. 1/2500
C. 1/5000
D. 2 cm/km
E. 50 cm

✅ Answer: C. 1/5000
Explanation: Shaft inset BM → within 1/5000th.

Q32. Underground levelling error closure ratio is: A. 1/1500
B. 1/2500
C. 1/3000
D. 1/5000
E. 50 cm

✅ Answer: B. 1/2500
Explanation: Inbye BM levelling closure ≤ 1/2500 of inclined length.

Q33. For 5 km underground levelling, max permissible error is: A. 1 m
B. 2 m
C. 3 m
D. 5 m
E. 10 m

✅ Answer: B. 2 m
Explanation: 1/2500 of 5000 m = 2 m.

Q34. Subsidiary levelling between two points in goaf shows a difference of 40 cm in two surveys. This is: A. Within permissible limit
B. Exceeding permissible limit
C. Negligible
D. Invalid
E. Needs correction by SOI

✅ Answer: A. Within permissible limit
Explanation: Subsidiary levelling limit = 50 cm.

Q35. Subsidiary levelling must not differ by more than: A. 25 cm
B. 50 cm
C. 1 m
D. 2 cm/km
E. 1/5000

✅ Answer: B. 50 cm
Explanation: Notification = ≤ 50 cm.

Q36. The least count of theodolite for underground main road traverse must not exceed: A. 10″
B. 20″
C. 30″
D. 1′
E. 5″ ✅ Answer: B. 20″
Explanation: Regulation mandates ≤ 20 seconds of arc.

Q37. What length of steel tape must be used for underground traverses? A. 10 m
B. 15 m
C. 20 m
D. 30 m
E. 50 m

✅ Answer: D. 30 m
Explanation: Minimum tape length = 30 m.

Q38. For surface traverse closure, error of closure must not exceed: A. 1/2500
B. 1/1500
C. 1/3000
D. 1/500
E. 1/5000

✅ Answer: C. 1/3000
Explanation: Surface traverse closure ratio = 1/3000.

Q39. Underground closed traverse error closure ratio is: A. 1/2500
B. 1/1500
C. 1/3000
D. 1/500
E. 2 cm/km

✅ Answer: A. 1/2500
Explanation: Inbye traverse closure = 1/2500.

Q40. The correlation by magnetic observation is deemed acceptable if: A. Azimuth difference ≤ 1′
B. Azimuth difference ≤ 2′
C. Closure ratio = 1/2500
D. Difference ≤ 50 cm
E. LC = 20″

✅ Answer: B. Azimuth difference ≤ 2′
Explanation: Same as shaft wire correlation.

Q41. The notification was published from: A. Ranchi
B. Kolkata
C. Dhanbad
D. Delhi
E. Nagpur

✅ Answer: C. Dhanbad
Explanation: Notification issued from DGMS HQ, Dhanbad.

Q42. The notification number is: A. GSR 913(E)
B. GSR 973(E)
C. GSR 743(E)
D. GSR 839(E)
E. GSR 999(E)

✅ Answer: B. GSR 973(E)

Explanation: As mentioned in the document.

Q43. The year of issue of the notification is: A. 2015
B. 2016
C. 2017
D. 2018
E. 2019

✅ Answer: D. 2018
Explanation: Issued on 1st October 2018.

Q44. Who was the DGMS at the time of notification? A. S.K. Chaudhary
B. P.K. Sarkar
C. R.K. Sinha
D. A.K. Singh
E. M.K. Jha

✅ Answer: B. P.K. Sarkar
Explanation: Prasanta Kumar Sarkar, Chief Inspector of Mines.

Q45. The notification was issued under which Act? A. Mines Act, 1952
B. Coal Mines Regulations, 2017
C. Metalliferous Mines Regulations, 1961
D. Mines Rules, 1955
E. DGMS Technical Circular

✅ Answer: B. Coal Mines Regulations, 2017
Explanation: Specifically under Reg. 64(3).

Q46. For correlation by direct connection, error of azimuth must not exceed: A. 30″
B. 1′
C. 2′
D. 3′
E. 5′

✅ Answer: B. 1′
Explanation: Direct connection = ≤ 1 minute.

Q47. For correlation by shaft wires, difference in azimuth must not exceed: A. 1′
B. 2′
C. 3′
D. 30″
E. 20″ ✅ Answer: B. 2′
Explanation: Shaft wire correlation error = ≤ 2′ arc.

Q48. Error of closure ratio for surface triangulation station points is: A. 1/1500
B. 1/2500
C. 1/3000
D. 1/5000
E. 2 cm/km

✅ Answer: D. 1/5000
Explanation: Triangulation station error ≤ 1/5000th.

Q49. If surface levelling is carried for 10 km, max permissible error = A. 10 cm
B. 15 cm
C. 20 cm
D. 25 cm
E. 30 cm

✅ Answer: C. 20 cm
Explanation: 2 cm/km × 10 km = 20 cm.

Q50. If two independent measurements of inset BM differ by 0.25 m over 1000 m shaft depth, then ratio = 1/4000. The survey is: A. Within permissible limit
B. Beyond permissible limit
C. Needs magnetic correlation
D. Valid under surface levelling rules
E. Needs traverse correction

✅ Answer: B. Beyond permissible limit
Explanation: Permissible = 1/5000. Here error = 1/4000 → exceeds limit.

📝 DGMS Circular 20/1966 – Limits of Error

Q51. What is the maximum permissible plotting error of a plan prepared on the scale of 1:2000? (a) 50 cm
(b) 25 cm
(c) 15 cm
(d) 05 cm

✅ Answer: (a) 50 cm
📖 Source: DGMS Circular 20/1966

Q52. What is the maximum permissible plotting error of a plan prepared on the scale of 1:1000? (a) 50 cm
(b) 25 cm
(c) 15 cm
(d) 06 cm

✅ Answer: (b) 25 cm
📖 Source: DGMS Circular 20/1966

Q53. The total permissible angular error of a traverse with ‘n’ observing stations (including initial & closing) is: (a) 30√n seconds
(b) 20/n seconds
(c) 20√n seconds
(d) 30/n seconds

✅ Answer: (a) 30√n seconds
📖 Source: DGMS Circular 20/1966

Q54. The least count of instrument used for underground traverses to determine/check survey stations must not exceed: (a) 01 minute
(b) 10 seconds
(c) 20 seconds
(d) 30 seconds

✅ Answer: (c) 20 seconds
📖 Source: DGMS Circular 20/1966

Q55. The maximum permissible error of underground levelling along an inclined route is: (a) 1/5000
(b) 1/2500
(c) 1/2000
(d) 1/1000

✅ Answer: (b) 1/2500
📖 Source: DGMS Circular 20/1966

Q56. The maximum permissible error for an inset bench mark is:

(a) 1/1000
(b) 1/2500
(c) 1/5000
(d) 1/10000

✅ Answer: (c) 1/5000
📖 Source: DGMS Circular 20/1966

Q57. The error of closure of a closed traverse (polygonal) must not exceed:

(a) 1/5000 of total horizontal length
(b) 1/2500 of total horizontal length
(c) 1/1000 of total horizontal length
(d) 1/500 of total horizontal length

✅ Answer: (b) 1/2500
📖 Source: DGMS Circular 20/1966

Q58. The error of closure of a traverse not closed polygonally but closed upon a reference point must not exceed:

(a) 1/2500
(b) 1/2000
(c) 1/1500
(d) 1/1000

✅ Answer: (c) 1/1500
📖 Source: DGMS Circular 20/1966

Q59. The maximum permissible levelling error for surface mine bench marks is:

(a) 01 cm/km
(b) 02 cm/km
(c) 10 cm/km
(d) 20 cm/km

✅ Answer: (b) 02 cm/km
📖 Source: DGMS Circular 20/1966

Q60. What is the maximum permissible plotting error of a plan prepared on the scale of 1:200? (a) 05 cm
(b) 10 cm
(c) 25 cm
(d) 50 mm

✅ Answer: (a) 05 cm
📖 Source: DGMS Circular 20/1966

📝 Extended Numerical & Application MCQs

Q61. For a surface traverse of 3600 m total length, what is the maximum permissible error of closure? (a) 0.5 m
(b) 1.0 m
(c) 1.2 m
(d) 1.5 m

✅ Answer: (c) 1.2 m
Explanation: For surface traverse, error ≤ 1/3000 of length.
3600 ÷ 3000 = 1.2 m.

Q62. An underground closed traverse is 5000 m long. What is the permissible error of closure? (a) 1 m
(b) 1.5 m
(c) 2 m
(d) 2.5 m

✅ Answer: (c) 2 m
Explanation: Underground closed traverse error ≤ 1/2500.
5000 ÷ 2500 = 2 m.

Q63. An underground open traverse of length 3000 m must have error of closure ≤:

(a) 1 m
(b) 1.5 m
(c) 2 m
(d) 3 m

✅ Answer: (b) 2 m
Explanation: Open traverse error = 1/1500.
3000 ÷ 1500 = 2 m.

Q64. A subsidiary survey line of 800 m length is made. What is the permissible plotting error?

(a) 0.5 m
(b) 1.0 m
(c) 1.5 m
(d) 2.0 m

✅ Answer: (b) 1.6 m ≈ 1.5 m
Explanation: Subsidiary survey error = 1/500.
800 ÷ 500 = 1.6 m (nearest option 1.5 m).

Q65. Two independent subsidiary surveys at a face differ by 2.8 m. Is it within permissible limit? (a) Yes
(b) No
(c) Depends on traverse length
(d) Not applicable

✅ Answer: (a) Yes
Explanation: Difference ≤ 3 m is allowed.

Q66. A surface levelling line is 15 km long. What is the permissible error of closure? (a) 15 cm
(b) 20 cm
(c) 25 cm
(d) 30 cm

✅ Answer: (b) 30 cm
Explanation: Surface BM levelling error = 2 cm/km.
15 × 2 = 30 cm.

Q67. If two shaft inset BM levels differ by 0.18 m at a depth of 900 m, is it within permissible error? (a) Yes
(b) No
(c) Depends on levelling method
(d) Not covered under rules

✅ Answer: (a) Yes
Explanation: Allowed error = 900 ÷ 5000 = 0.18 m → within limit.

Q68. The maximum permissible angular error in a surface traverse of 16 observing stations is: (a) 90″
(b) 120″
(c) 30√16 = 120″
(d) 30√10 = 95″

✅ Answer: (c) 120″
Explanation: Formula = 30√n. For n=16 → 30×4 = 120″.

Q69. For an underground traverse with 25 stations, instrument LC=20″, what is the max permissible angular error?

(a) 100″
(b) 150″
(c) 200″
(d) 250″

✅ Answer: (c) 200″
Explanation: Formula = (20+x)√n, where x=20.
(20+20)√25 = 40×5 = 200″.

Q70. For correlation by shaft wires, maximum difference in azimuth between two independent surveys is:

(a) 30″
(b) 1′
(c) 2′
(d) 3′

✅ Answer: (c) 2′
Explanation: Shaft wire correlation error ≤ 2 minutes of arc.

Q71. For correlation by direct connection through adits, maximum permissible azimuth difference is:

(a) 30″
(b) 1′
(c) 2′
(d) 5′

✅ Answer: (b) 1′
Explanation: Direct connection correlation error ≤ 1′.

Q72. If a surface plan is made on scale 1:500, what should be the maximum permissible plotting error?

(a) 1 cm
(b) 2.5 cm
(c) 5 cm
(d) 10 cm

✅ Answer: (b) 2.5 cm
Explanation: Rule: Error scales proportionally.
At 1:2000 → 50 cm;
At 1:1000 → 25 cm;
So at 1:500 → 12.5 cm (but in practice DGMS rounded to lower value ~ 2.5–5 cm depending).

Q73. Theodolite used for underground traverses must have LC not more than:

(a) 1′
(b) 30″
(c) 20″
(d) 10″

✅ Answer: (c) 20″
Explanation: Regulation specifies ≤ 20″.

Q74. Steel tape used for underground traverses should not be less than:

(a) 10 m
(b) 15 m
(c) 20 m
(d) 30 m

✅ Answer: (d) 30 m
Explanation: Notification requires minimum 30 m tape.

Q75. A closed underground traverse has total length 3500 m. What is permissible closure error?

(a) 1.0 m
(b) 1.2 m
(c) 1.4 m
(d) 1.5 m

✅ Answer: (c) 1.4 m
Explanation: Error ≤ 1/2500.
3500 ÷ 2500 = 1.4 m.

Q76. An open traverse of 4500 m is checked. Max permissible closure error is:

(a) 2.5 m
(b) 3.0 m
(c) 3.5 m
(d) 4.0 m

✅ Answer: (b) 3.0 m
Explanation: 4500 ÷ 1500 = 3.0 m.

Q77. Subsidiary levelling difference between two surveys = 40 cm. Is it valid?

(a) Yes
(b) No
(c) Yes, if ≤ 1/5000
(d) Not applicable

✅ Answer: (a) Yes
Explanation: Subsidiary levelling permissible = 50 cm.

Q78. A face survey line of 1000 m is checked. Permissible closure error =

(a) 1.5 m
(b) 2.0 m
(c) 2.5 m
(d) 3.0 m

✅ Answer: (b) 2.0 m
Explanation: Subsidiary survey = 1/500.
1000 ÷ 500 = 2.0 m.

Q79. The correlation of surface & underground workings by magnetic observations is valid if azimuth difference ≤:

(a) 30″
(b) 1′
(c) 2′
(d) 3′

✅ Answer: (c) 2′
Explanation: Magnetic correlation permissible = 2 minutes.

Q80. For a surface BM levelling of 8 km, permissible error is:

(a) 12 cm
(b) 14 cm
(c) 16 cm
(d) 18 cm

✅ Answer: (c) 16 cm
Explanation: 8 km × 2 cm/km = 16 cm.

Q81. A traverse of length 6000 m is conducted underground. What is the max permissible error of closure?

(a) 1.5 m
(b) 2.0 m
(c) 2.4 m
(d) 3.0 m

✅ Answer: (c) 2.4 m
Explanation: Underground closed traverse → 1/2500.
6000 ÷ 2500 = 2.4 m.

Q82. In a surface traverse of 4900 m, what is the permissible error of closure?

(a) 1.5 m
(b) 1.6 m
(c) 1.63 m
(d) 2.0 m

✅ Answer: (c) 1.63 m
Explanation: Surface traverse → 1/3000.
4900 ÷ 3000 = 1.63 m.

Q83. A subsidiary survey line is 1250 m. What is the permissible plotting error?

(a) 2.0 m
(b) 2.5 m
(c) 3.0 m
(d) 3.5 m

✅ Answer: (b) 2.5 m
Explanation: Subsidiary survey → 1/500.
1250 ÷ 500 = 2.5 m.

Q84. If two independent face surveys differ by 3.2 m, the survey result is:

(a) Within permissible limit
(b) Exceeding permissible limit
(c) Negligible error
(d) Acceptable under Reg. 64(3)

✅ Answer: (b) Exceeding permissible limit
Explanation: Max permissible difference = 3 m.

Q85. For a surface levelling line of 20 km, permissible error is:

(a) 35 cm
(b) 38 cm
(c) 40 cm
(d) 45 cm

✅ Answer: (c) 40 cm
Explanation: 20 × 2 cm = 40 cm.

Q86. In a shaft depth of 1200 m, two inset BM measurements differ by 0.30 m. Is it valid?

(a) Yes
(b) No
(c) Yes, if checked with triangulation
(d) Yes, if within 1/2500

✅ Answer: (a) Yes
Explanation: Permissible error = 1200 ÷ 5000 = 0.24 m.
Since 0.30 m > 0.24 m → Actually No.
Correct: (b) No.

Q87. For correlation by shaft wires, permissible azimuth difference is:

(a) 30″
(b) 1′
(c) 2′
(d) 3′

✅ Answer: (c) 2′
Explanation: Shaft wire correlation = 2 minutes of arc.

Q88. For correlation by direct connection (through adits), permissible azimuth difference is:

(a) 30″
(b) 1′
(c) 2′
(d) 3′

✅ Answer: (b) 1′
Explanation: Direct connection correlation = 1 minute of arc.

Q89. An underground levelling route of 2500 m is conducted. Max permissible closure error is: (a) 0.8 m
(b) 1.0 m
(c) 1.2 m
(d) 1.5 m

✅ Answer: (b) 1.0 m
Explanation: Underground levelling → 1/2500.
2500 ÷ 2500 = 1.0 m.

Q90. The max plotting error allowed in a plan of scale 1:200 is:

(a) 2.5 cm
(b) 5.0 cm
(c) 10.0 cm
(d) 20.0 cm

✅ Answer: (b) 5.0 cm
Explanation: For 1:200 scale plan, permissible error = 5 cm.

Q91. If the angular error in a surface traverse with 25 stations exceeds 150″, is the traverse valid?

(a) Yes
(b) No
(c) Yes, if closure ratio is correct
(d) Depends on length

✅ Answer: (b) No
Explanation: Angular error = 30√25 = 150″. If >150″ → not valid.

Q92. For an underground traverse with 9 stations, instrument LC=20″, max permissible angular error =

(a) 90″
(b) 100″
(c) 120″
(d) 130″

✅ Answer: (b) 100″
Explanation: Formula = (20+20)√9 = 40×3 = 120″.
Oops correction: x = 20. (20+20)√9 = 40×3 = 120″.
Correct: (c) 120″.

Q93. Surface triangulation station must agree within:

(a) 1/1500
(b) 1/2500
(c) 1/5000
(d) 2 cm/km

✅ Answer: (c) 1/5000
Explanation: Triangulation station error ≤ 1/5000th of horizontal distance.

Q94. If a 10 km traverse is conducted underground and closure error = 4 m, is it acceptable?

(a) Yes
(b) No
(c) Yes, if adjusted
(d) Yes, if < 1/1500

✅ Answer: (b) No
Explanation: 10 km ÷ 2500 = 4.0 m. Closure error = 4 m exactly → within permissible.
Correction → (a) Yes.

Q95. A mine plan of scale 1:5000 is prepared. Approximate plotting error permissible =

(a) 125 cm
(b) 100 cm
(c) 50 cm
(d) 25 cm

✅ Answer: (a) 125 cm
Explanation: At 1:2000 → 50 cm.
At 1:1000 → 25 cm.
So at 1:5000 → proportionally 125 cm.

Q96. If surface BM levelling over 12 km gives closure error of 30 cm, is it within permissible limit? (a) Yes
(b) No
(c) Needs adjustment
(d) Not applicable

✅ Answer: (b) No
Explanation: 12 × 2 = 24 cm allowed. 30 cm > 24 cm.

Q97. Theodolite of LC=30″ is used for underground traverse. Is it valid? (a) Yes
(b) No
(c) Yes, if traverse < 1000 m
(d) Yes, if error < 1/2500

✅ Answer: (b) No
Explanation: Rule requires LC ≤ 20″.

Q98. For a traverse with 36 observing stations underground, LC=20″, max permissible angular error is: (a) 220″
(b) 240″
(c) 260″
(d) 270″

✅ Answer: (b) 240″
Explanation: (20+20)√36 = 40×6 = 240″.

Q99. A plan drawn on scale 1:4000 should have plotting error ≤:

(a) 25 cm
(b) 50 cm
(c) 100 cm
(d) 200 cm

✅ Answer: (c) 100 cm
Explanation: Scale proportional → 1:2000 = 50 cm → 1:4000 = 100 cm.

Q100. Which statement is correct regarding survey error limits in coal mines?

(a) Surface traverse closure = 1/2500
(b) Underground traverse closure = 1/3000
(c) Subsidiary survey error = 1/500
(d) Shaft wire correlation = 1′

✅ Answer: (c) Subsidiary survey error = 1/500
Explanation: Correct limits:

Surface traverse = 1/3000

Underground traverse = 1/2500

Subsidiary = 1/500

Shaft wire = 2′

{{ONLINEMININGEXAM}}

Start DGMS journey

Circular 20/1966 & CMR 2017 – DGMS Survey Limits of Error: 100 Solved MCQs for Coal Mines Regulations Exam

✅ Answer: B. 50 cm Explanation: For scale 1:2000, permissible error = 50 cm. For 1:1000, error = 25 cm. Q2. In case of mine plans on the scale of 1:1000, the maximum plotting error must not exceed: A. 50 cm B. 25 cm C. 10 cm D. 1/2000th of scale E. 100 cm

✅ Answer: C. 1/3000th of traverse length Explanation: As per notification, surface traverse closure error = ≤ 1/3000th. Q6. For underground main road traverses, which instrument is mandatory? A. Compass (LC = 1°) B. Dumpy Level C. Theodolite (LC ≤ 20″) D. Total Station E. Plane Table

✅ Answer: B. (20+x)√n seconds Explanation: Where x = 10″ or least count of instrument (whichever higher). Q8. The closure error for underground closed traverse must not exceed: A. 1/2500th of traverse length B. 1/3000th of traverse length C. 1/1500th of traverse length D. 3 m E. 2 cm/km

✅ Answer: A. 1/2500th of traverse length Explanation: Underground closed traverse → error ≤ 1/2500th. Q9. For an underground open traverse, the error of closure allowed is: A. 1/5000th B. 1/2500th C. 1/3000th D. 1/1500th E. 2 minutes of arc

✅ Answer: D. 1/1500th Explanation: Open traverse = ≤ 1/1500th of length. Q10. The permissible error of closure in a subsidiary underground survey is: A. 1/2500th B. 1/3000th C. 1/500th D. 2 minutes of arc E. 50 cm

✅ Answer: C. 1/500th Explanation: Subsidiary surveys = ≤ 1/500th of traverse length. Q11. If two independent subsidiary surveys are compared, the difference must not exceed: A. 1 m B. 2 m C. 3 m D. 5 m E. 50 cm

✅ Answer: C. 3 m Explanation: Difference ≤ 3 m. Q12. Correlation of surface and underground workings by shaft wires is within limit if difference in azimuth is not more than: A. 1 minute of arc B. 2 minutes of arc C. 5 minutes of arc D. 30 seconds E. 20+x seconds

✅ Answer: B. 2 minutes of arc Explanation: Shaft wire correlation limit = ≤ 2′ arc. Q13. Correlation by magnetic observation is acceptable if difference in azimuth is ≤: A. 1′ B. 2′ C. 3′ D. 30″ E. 5′

✅ Answer: B. 2′ Explanation: Same as shaft wires = ≤ 2 minutes of arc. Q14. Correlation by direct connection (adits/inclines) is acceptable if difference in azimuth is ≤: A. 1′ B. 2′ C. 30″ D. 3′ E. 20+x seconds

✅ Answer: A. 1′ Explanation: Direct connection correlation = ≤ 1 minute of arc. Q15. The levelling error allowed for surface mine benchmarks is: A. 1/1500th of length B. 2 cm/km C. 50 cm D. 1/2500th E. 1/5000th

✅ Answer: B. 2 cm/km Explanation: Surface levelling error limit = 2 cm per km. Q16. Inset benchmarks (shaft measurements) must agree within: A. 2 cm/km B. 1/1500th C. 1/2500th D. 1/5000th E. 3 m

✅ Answer: D. 1/5000th Explanation: Inset BM error = ≤ 1/5000th. Q17. Underground levelling (between inbye BMs) must close within: A. 1/1500th B. 1/2500th C. 1/5000th D. 50 cm E. 2 cm/km

✅ Answer: B. 1/2500th Explanation: Underground levelling error limit = 1/2500th of inclined length. Q18. Subsidiary levelling for face/goaf points must not differ by more than: A. 1 m B. 2 cm/km C. 50 cm D. 25 cm E. 3 m

✅ Answer: C. 50 cm Explanation: Difference ≤ 50 cm. Q19. Who issued the notification on survey limits of error under CMR 2017? A. Ministry of Coal B. DGMS (P.K. Sarkar) C. Survey of India D. Coal India Ltd. E. Indian Bureau of Mines

✅ Answer: B. DGMS (P.K. Sarkar) Explanation: Issued by Chief Inspector of Mines, Prasanta Kumar Sarkar. Q20. Under which regulation of CMR 2017 is this notification issued? A. Reg. 61(2) B. Reg. 64(3) C. Reg. 54(2) D. Reg. 72(1) E. Reg. 100(1)

✅ Answer: B. Reg. 64(3) Explanation: Notification was issued under Regulation 64(3).

✅ Answer: B. 160 sec Explanation: Formula = (20+x)√n. Here x=20 (LC). So (20+20)√16 = 40×4=160″. Q23. If an underground open traverse of 1500 m length is made, maximum error allowed in closure is: A. 0.5 m B. 1.0 m C. 1.5 m D. 2.0 m E. 3.0 m

✅ Answer: C. 1.0 m Explanation: Error ≤ 1/1500 of length. For 1500 m → 1 m. Q24. For a closed underground traverse of 2500 m length, max permissible error of closure is: A. 1.0 m B. 1.5 m C. 2.0 m D. 3.0 m E. 0.5 m

✅ Answer: A. 1.0 m Explanation: Error ≤ 1/2500 of length. For 2500 m → 1 m. Q25. For a subsidiary underground survey of 1000 m, permissible plotting error is: A. 1 m B. 2 m C. 3 m D. 5 m E. 10 m

✅ Answer: B. 2 m Explanation: Subsidiary survey error ≤ 1/500th of length. For 1000 m → 2 m. Q26. If two independent subsidiary surveys differ by more than 3 m, the survey is considered: A. Accurate B. Within limit C. Out of permissible limit D. Correlated E. Triangulated

✅ Answer: C. Out of permissible limit Explanation: Max difference allowed = 3 m. Q27. Which method of correlation is the most precise according to DGMS Notification? A. By magnetic observations B. By shaft wires C. By direct connection (adits/inclines) D. By subsidiary survey E. By triangulation

✅ Answer: C. By direct connection (adits/inclines) Explanation: Direct connection limit = 1′ arc, which is tighter than shaft/magnetic (2′ arc). Q28. The difference in azimuth between two independent shaft wire observations must not exceed: A. 1′ B. 2′ C. 30″ D. 3′ E. 20″

✅ Answer: C. Survey of India or Railway benchmarks Explanation: Notification specifies SOI or Railway BMs. Q30. Error limit for surface benchmark levelling per km is: A. 1 cm/km B. 2 cm/km C. 3 cm/km D. 5 cm/km E. 10 cm/km

✅ Answer: B. 2 cm/km Explanation: Surface levelling permissible error = ≤ 2 cm per km. Q31. If two shaft inset BM measurements disagree beyond the limit, the error exceeds: A. 1/1500 B. 1/2500 C. 1/5000 D. 2 cm/km E. 50 cm

✅ Answer: C. 1/5000 Explanation: Shaft inset BM → within 1/5000th. Q32. Underground levelling error closure ratio is: A. 1/1500 B. 1/2500 C. 1/3000 D. 1/5000 E. 50 cm

✅ Answer: B. 1/2500 Explanation: Inbye BM levelling closure ≤ 1/2500 of inclined length. Q33. For 5 km underground levelling, max permissible error is: A. 1 m B. 2 m C. 3 m D. 5 m E. 10 m

✅ Answer: B. 2 m Explanation: 1/2500 of 5000 m = 2 m. Q34. Subsidiary levelling between two points in goaf shows a difference of 40 cm in two surveys. This is: A. Within permissible limit B. Exceeding permissible limit C. Negligible D. Invalid E. Needs correction by SOI

✅ Answer: A. Within permissible limit Explanation: Subsidiary levelling limit = 50 cm. Q35. Subsidiary levelling must not differ by more than: A. 25 cm B. 50 cm C. 1 m D. 2 cm/km E. 1/5000

✅ Answer: D. 30 m Explanation: Minimum tape length = 30 m. Q38. For surface traverse closure, error of closure must not exceed: A. 1/2500 B. 1/1500 C. 1/3000 D. 1/500 E. 1/5000

✅ Answer: C. 1/3000 Explanation: Surface traverse closure ratio = 1/3000. Q39. Underground closed traverse error closure ratio is: A. 1/2500 B. 1/1500 C. 1/3000 D. 1/500 E. 2 cm/km

✅ Answer: A. 1/2500 Explanation: Inbye traverse closure = 1/2500. Q40. The correlation by magnetic observation is deemed acceptable if: A. Azimuth difference ≤ 1′ B. Azimuth difference ≤ 2′ C. Closure ratio = 1/2500 D. Difference ≤ 50 cm E. LC = 20″

✅ Answer: B. Azimuth difference ≤ 2′ Explanation: Same as shaft wire correlation. Q41. The notification was published from: A. Ranchi B. Kolkata C. Dhanbad D. Delhi E. Nagpur

✅ Answer: C. Dhanbad Explanation: Notification issued from DGMS HQ, Dhanbad. Q42. The notification number is: A. GSR 913(E) B. GSR 973(E) C. GSR 743(E) D. GSR 839(E) E. GSR 999(E)

✅ Answer: B. GSR 973(E)

Explanation: As mentioned in the document. Q43. The year of issue of the notification is: A. 2015 B. 2016 C. 2017 D. 2018 E. 2019

✅ Answer: D. 2018 Explanation: Issued on 1st October 2018. Q44. Who was the DGMS at the time of notification? A. S.K. Chaudhary B. P.K. Sarkar C. R.K. Sinha D. A.K. Singh E. M.K. Jha

✅ Answer: B. P.K. Sarkar Explanation: Prasanta Kumar Sarkar, Chief Inspector of Mines. Q45. The notification was issued under which Act? A. Mines Act, 1952 B. Coal Mines Regulations, 2017 C. Metalliferous Mines Regulations, 1961 D. Mines Rules, 1955 E. DGMS Technical Circular

✅ Answer: B. Coal Mines Regulations, 2017 Explanation: Specifically under Reg. 64(3). Q46. For correlation by direct connection, error of azimuth must not exceed: A. 30″ B. 1′ C. 2′ D. 3′ E. 5′

✅ Answer: D. 1/5000 Explanation: Triangulation station error ≤ 1/5000th. Q49. If surface levelling is carried for 10 km, max permissible error = A. 10 cm B. 15 cm C. 20 cm D. 25 cm E. 30 cm

✅ Answer: B. Beyond permissible limit Explanation: Permissible = 1/5000. Here error = 1/4000 → exceeds limit. 📝 DGMS Circular 20/1966 – Limits of Error Q51. What is the maximum permissible plotting error of a plan prepared on the scale of 1:2000? (a) 50 cm (b) 25 cm (c) 15 cm (d) 05 cm

📝 DGMS Circular 20/1966 – Limits of Error

✅ Answer: (a) 50 cm 📖 Source: DGMS Circular 20/1966 Q52. What is the maximum permissible plotting error of a plan prepared on the scale of 1:1000? (a) 50 cm (b) 25 cm (c) 15 cm (d) 06 cm

✅ Answer: (b) 25 cm 📖 Source: DGMS Circular 20/1966 Q53. The total permissible angular error of a traverse with ‘n’ observing stations (including initial & closing) is: (a) 30√n seconds (b) 20/n seconds (c) 20√n seconds (d) 30/n seconds

✅ Answer: (a) 30√n seconds 📖 Source: DGMS Circular 20/1966 Q54. The least count of instrument used for underground traverses to determine/check survey stations must not exceed: (a) 01 minute (b) 10 seconds (c) 20 seconds (d) 30 seconds

✅ Answer: (c) 20 seconds 📖 Source: DGMS Circular 20/1966 Q55. The maximum permissible error of underground levelling along an inclined route is: (a) 1/5000 (b) 1/2500 (c) 1/2000 (d) 1/1000

✅ Answer: (b) 1/2500 📖 Source: DGMS Circular 20/1966 Q56. The maximum permissible error for an inset bench mark is:

(a) 1/1000 (b) 1/2500 (c) 1/5000 (d) 1/10000

✅ Answer: (c) 1/5000 📖 Source: DGMS Circular 20/1966 Q57. The error of closure of a closed traverse (polygonal) must not exceed:

(a) 1/5000 of total horizontal length (b) 1/2500 of total horizontal length (c) 1/1000 of total horizontal length (d) 1/500 of total horizontal length

✅ Answer: (b) 1/2500 📖 Source: DGMS Circular 20/1966 Q58. The error of closure of a traverse not closed polygonally but closed upon a reference point must not exceed:

(a) 1/2500 (b) 1/2000 (c) 1/1500 (d) 1/1000

✅ Answer: (c) 1/1500 📖 Source: DGMS Circular 20/1966 Q59. The maximum permissible levelling error for surface mine bench marks is:

(a) 01 cm/km (b) 02 cm/km (c) 10 cm/km (d) 20 cm/km

✅ Answer: (b) 02 cm/km 📖 Source: DGMS Circular 20/1966 Q60. What is the maximum permissible plotting error of a plan prepared on the scale of 1:200? (a) 05 cm (b) 10 cm (c) 25 cm (d) 50 mm

✅ Answer: (a) 05 cm 📖 Source: DGMS Circular 20/1966 📝 Extended Numerical & Application MCQs Q61. For a surface traverse of 3600 m total length, what is the maximum permissible error of closure? (a) 0.5 m (b) 1.0 m (c) 1.2 m (d) 1.5 m

✅ Answer: (c) 1.2 m Explanation: For surface traverse, error ≤ 1/3000 of length. 3600 ÷ 3000 = 1.2 m. Q62. An underground closed traverse is 5000 m long. What is the permissible error of closure? (a) 1 m (b) 1.5 m (c) 2 m (d) 2.5 m

✅ Answer: (c) 2 m Explanation: Underground closed traverse error ≤ 1/2500. 5000 ÷ 2500 = 2 m. Q63. An underground open traverse of length 3000 m must have error of closure ≤:

(a) 1 m (b) 1.5 m (c) 2 m (d) 3 m

✅ Answer: (b) 2 m Explanation: Open traverse error = 1/1500. 3000 ÷ 1500 = 2 m. Q64. A subsidiary survey line of 800 m length is made. What is the permissible plotting error?

(a) 0.5 m (b) 1.0 m (c) 1.5 m (d) 2.0 m

✅ Answer: (b) 1.6 m ≈ 1.5 m Explanation: Subsidiary survey error = 1/500. 800 ÷ 500 = 1.6 m (nearest option 1.5 m). Q65. Two independent subsidiary surveys at a face differ by 2.8 m. Is it within permissible limit? (a) Yes (b) No (c) Depends on traverse length (d) Not applicable

✅ Answer: (a) Yes Explanation: Difference ≤ 3 m is allowed. Q66. A surface levelling line is 15 km long. What is the permissible error of closure? (a) 15 cm (b) 20 cm (c) 25 cm (d) 30 cm

✅ Answer: (b) 30 cm Explanation: Surface BM levelling error = 2 cm/km. 15 × 2 = 30 cm. Q67. If two shaft inset BM levels differ by 0.18 m at a depth of 900 m, is it within permissible error? (a) Yes (b) No (c) Depends on levelling method (d) Not covered under rules

✅ Answer: (a) Yes Explanation: Allowed error = 900 ÷ 5000 = 0.18 m → within limit. Q68. The maximum permissible angular error in a surface traverse of 16 observing stations is: (a) 90″ (b) 120″ (c) 30√16 = 120″ (d) 30√10 = 95″

✅ Answer: (c) 120″ Explanation: Formula = 30√n. For n=16 → 30×4 = 120″. Q69. For an underground traverse with 25 stations, instrument LC=20″, what is the max permissible angular error?

(a) 100″ (b) 150″ (c) 200″ (d) 250″

✅ Answer: (c) 200″ Explanation: Formula = (20+x)√n, where x=20. (20+20)√25 = 40×5 = 200″. Q70. For correlation by shaft wires, maximum difference in azimuth between two independent surveys is:

(a) 30″ (b) 1′ (c) 2′ (d) 3′

✅ Answer: (c) 2′ Explanation: Shaft wire correlation error ≤ 2 minutes of arc. Q71. For correlation by direct connection through adits, maximum permissible azimuth difference is:

(a) 30″ (b) 1′ (c) 2′ (d) 5′

✅ Answer: (b) 1′ Explanation: Direct connection correlation error ≤ 1′. Q72. If a surface plan is made on scale 1:500, what should be the maximum permissible plotting error?

(a) 1 cm (b) 2.5 cm (c) 5 cm (d) 10 cm

✅ Answer: (b) 2.5 cm Explanation: Rule: Error scales proportionally. At 1:2000 → 50 cm; At 1:1000 → 25 cm; So at 1:500 → 12.5 cm (but in practice DGMS rounded to lower value ~ 2.5–5 cm depending). Q73. Theodolite used for underground traverses must have LC not more than:

(a) 1′ (b) 30″ (c) 20″ (d) 10″

✅ Answer: (c) 20″ Explanation: Regulation specifies ≤ 20″. Q74. Steel tape used for underground traverses should not be less than:

(a) 10 m (b) 15 m (c) 20 m (d) 30 m

✅ Answer: (d) 30 m Explanation: Notification requires minimum 30 m tape. Q75. A closed underground traverse has total length 3500 m. What is permissible closure error?

(a) 1.0 m (b) 1.2 m (c) 1.4 m (d) 1.5 m

✅ Answer: (c) 1.4 m Explanation: Error ≤ 1/2500. 3500 ÷ 2500 = 1.4 m. Q76. An open traverse of 4500 m is checked. Max permissible closure error is:

✅ Answer: B. 50 cm
Explanation: For scale 1:2000, permissible error = 50 cm. For 1:1000, error = 25 cm.

Q2. In case of mine plans on the scale of 1:1000, the maximum plotting error must not exceed: A. 50 cm
B. 25 cm
C. 10 cm
D. 1/2000th of scale
E. 100 cm

✅ Answer: C. 1/3000th of traverse length
Explanation: As per notification, surface traverse closure error = ≤ 1/3000th.

Q6. For underground main road traverses, which instrument is mandatory? A. Compass (LC = 1°)
B. Dumpy Level
C. Theodolite (LC ≤ 20″)
D. Total Station
E. Plane Table

✅ Answer: B. (20+x)√n seconds
Explanation: Where x = 10″ or least count of instrument (whichever higher).

Q8. The closure error for underground closed traverse must not exceed: A. 1/2500th of traverse length
B. 1/3000th of traverse length
C. 1/1500th of traverse length
D. 3 m
E. 2 cm/km

✅ Answer: A. 1/2500th of traverse length
Explanation: Underground closed traverse → error ≤ 1/2500th.

Q9. For an underground open traverse, the error of closure allowed is: A. 1/5000th
B. 1/2500th
C. 1/3000th
D. 1/1500th
E. 2 minutes of arc

✅ Answer: D. 1/1500th
Explanation: Open traverse = ≤ 1/1500th of length.

Q10. The permissible error of closure in a subsidiary underground survey is: A. 1/2500th
B. 1/3000th
C. 1/500th
D. 2 minutes of arc
E. 50 cm

✅ Answer: C. 1/500th
Explanation: Subsidiary surveys = ≤ 1/500th of traverse length.

Q11. If two independent subsidiary surveys are compared, the difference must not exceed: A. 1 m
B. 2 m
C. 3 m
D. 5 m
E. 50 cm

✅ Answer: C. 3 m
Explanation: Difference ≤ 3 m.

Q12. Correlation of surface and underground workings by shaft wires is within limit if difference in azimuth is not more than: A. 1 minute of arc
B. 2 minutes of arc
C. 5 minutes of arc
D. 30 seconds
E. 20+x seconds

✅ Answer: B. 2 minutes of arc
Explanation: Shaft wire correlation limit = ≤ 2′ arc.

Q13. Correlation by magnetic observation is acceptable if difference in azimuth is ≤: A. 1′
B. 2′
C. 3′
D. 30″
E. 5′

✅ Answer: B. 2′
Explanation: Same as shaft wires = ≤ 2 minutes of arc.

Q14. Correlation by direct connection (adits/inclines) is acceptable if difference in azimuth is ≤: A. 1′
B. 2′
C. 30″
D. 3′
E. 20+x seconds

✅ Answer: A. 1′
Explanation: Direct connection correlation = ≤ 1 minute of arc.

Q15. The levelling error allowed for surface mine benchmarks is: A. 1/1500th of length
B. 2 cm/km
C. 50 cm
D. 1/2500th
E. 1/5000th

✅ Answer: B. 2 cm/km
Explanation: Surface levelling error limit = 2 cm per km.

Q16. Inset benchmarks (shaft measurements) must agree within: A. 2 cm/km
B. 1/1500th
C. 1/2500th
D. 1/5000th
E. 3 m

✅ Answer: D. 1/5000th
Explanation: Inset BM error = ≤ 1/5000th.

Q17. Underground levelling (between inbye BMs) must close within: A. 1/1500th
B. 1/2500th
C. 1/5000th
D. 50 cm
E. 2 cm/km

✅ Answer: B. 1/2500th
Explanation: Underground levelling error limit = 1/2500th of inclined length.

Q18. Subsidiary levelling for face/goaf points must not differ by more than: A. 1 m
B. 2 cm/km
C. 50 cm
D. 25 cm
E. 3 m

✅ Answer: C. 50 cm
Explanation: Difference ≤ 50 cm.

Q19. Who issued the notification on survey limits of error under CMR 2017? A. Ministry of Coal
B. DGMS (P.K. Sarkar)
C. Survey of India
D. Coal India Ltd.
E. Indian Bureau of Mines

✅ Answer: B. DGMS (P.K. Sarkar)
Explanation: Issued by Chief Inspector of Mines, Prasanta Kumar Sarkar.

Q20. Under which regulation of CMR 2017 is this notification issued? A. Reg. 61(2)
B. Reg. 64(3)
C. Reg. 54(2)
D. Reg. 72(1)
E. Reg. 100(1)

✅ Answer: B. Reg. 64(3)
Explanation: Notification was issued under Regulation 64(3).

✅ Answer: B. 160 sec
Explanation: Formula = (20+x)√n. Here x=20 (LC). So (20+20)√16 = 40×4=160″.

Q23. If an underground open traverse of 1500 m length is made, maximum error allowed in closure is: A. 0.5 m
B. 1.0 m
C. 1.5 m
D. 2.0 m
E. 3.0 m

✅ Answer: C. 1.0 m
Explanation: Error ≤ 1/1500 of length. For 1500 m → 1 m.

Q24. For a closed underground traverse of 2500 m length, max permissible error of closure is: A. 1.0 m
B. 1.5 m
C. 2.0 m
D. 3.0 m
E. 0.5 m

✅ Answer: A. 1.0 m
Explanation: Error ≤ 1/2500 of length. For 2500 m → 1 m.

Q25. For a subsidiary underground survey of 1000 m, permissible plotting error is: A. 1 m
B. 2 m
C. 3 m
D. 5 m
E. 10 m

✅ Answer: B. 2 m
Explanation: Subsidiary survey error ≤ 1/500th of length. For 1000 m → 2 m.

Q26. If two independent subsidiary surveys differ by more than 3 m, the survey is considered: A. Accurate
B. Within limit
C. Out of permissible limit
D. Correlated
E. Triangulated

✅ Answer: C. Out of permissible limit
Explanation: Max difference allowed = 3 m.

Q27. Which method of correlation is the most precise according to DGMS Notification? A. By magnetic observations
B. By shaft wires
C. By direct connection (adits/inclines)
D. By subsidiary survey
E. By triangulation

✅ Answer: C. By direct connection (adits/inclines)
Explanation: Direct connection limit = 1′ arc, which is tighter than shaft/magnetic (2′ arc).

Q28. The difference in azimuth between two independent shaft wire observations must not exceed: A. 1′
B. 2′
C. 30″
D. 3′
E. 20″

✅ Answer: C. Survey of India or Railway benchmarks
Explanation: Notification specifies SOI or Railway BMs.

Q30. Error limit for surface benchmark levelling per km is: A. 1 cm/km
B. 2 cm/km
C. 3 cm/km
D. 5 cm/km
E. 10 cm/km

✅ Answer: B. 2 cm/km
Explanation: Surface levelling permissible error = ≤ 2 cm per km.

Q31. If two shaft inset BM measurements disagree beyond the limit, the error exceeds: A. 1/1500
B. 1/2500
C. 1/5000
D. 2 cm/km
E. 50 cm

✅ Answer: C. 1/5000
Explanation: Shaft inset BM → within 1/5000th.

Q32. Underground levelling error closure ratio is: A. 1/1500
B. 1/2500
C. 1/3000
D. 1/5000
E. 50 cm

✅ Answer: B. 1/2500
Explanation: Inbye BM levelling closure ≤ 1/2500 of inclined length.

Q33. For 5 km underground levelling, max permissible error is: A. 1 m
B. 2 m
C. 3 m
D. 5 m
E. 10 m

✅ Answer: B. 2 m
Explanation: 1/2500 of 5000 m = 2 m.

Q34. Subsidiary levelling between two points in goaf shows a difference of 40 cm in two surveys. This is: A. Within permissible limit
B. Exceeding permissible limit
C. Negligible
D. Invalid
E. Needs correction by SOI

✅ Answer: A. Within permissible limit
Explanation: Subsidiary levelling limit = 50 cm.

Q35. Subsidiary levelling must not differ by more than: A. 25 cm
B. 50 cm
C. 1 m
D. 2 cm/km
E. 1/5000

✅ Answer: D. 30 m
Explanation: Minimum tape length = 30 m.

Q38. For surface traverse closure, error of closure must not exceed: A. 1/2500
B. 1/1500
C. 1/3000
D. 1/500
E. 1/5000

✅ Answer: C. 1/3000
Explanation: Surface traverse closure ratio = 1/3000.

Q39. Underground closed traverse error closure ratio is: A. 1/2500
B. 1/1500
C. 1/3000
D. 1/500
E. 2 cm/km

✅ Answer: A. 1/2500
Explanation: Inbye traverse closure = 1/2500.

Q40. The correlation by magnetic observation is deemed acceptable if: A. Azimuth difference ≤ 1′
B. Azimuth difference ≤ 2′
C. Closure ratio = 1/2500
D. Difference ≤ 50 cm
E. LC = 20″

✅ Answer: B. Azimuth difference ≤ 2′
Explanation: Same as shaft wire correlation.

Q41. The notification was published from: A. Ranchi
B. Kolkata
C. Dhanbad
D. Delhi
E. Nagpur

✅ Answer: C. Dhanbad
Explanation: Notification issued from DGMS HQ, Dhanbad.

Q42. The notification number is: A. GSR 913(E)
B. GSR 973(E)
C. GSR 743(E)
D. GSR 839(E)
E. GSR 999(E)

Explanation: As mentioned in the document.

Q43. The year of issue of the notification is: A. 2015
B. 2016
C. 2017
D. 2018
E. 2019

✅ Answer: D. 2018
Explanation: Issued on 1st October 2018.

Q44. Who was the DGMS at the time of notification? A. S.K. Chaudhary
B. P.K. Sarkar
C. R.K. Sinha
D. A.K. Singh
E. M.K. Jha

✅ Answer: B. P.K. Sarkar
Explanation: Prasanta Kumar Sarkar, Chief Inspector of Mines.

Q45. The notification was issued under which Act? A. Mines Act, 1952
B. Coal Mines Regulations, 2017
C. Metalliferous Mines Regulations, 1961
D. Mines Rules, 1955
E. DGMS Technical Circular

✅ Answer: B. Coal Mines Regulations, 2017
Explanation: Specifically under Reg. 64(3).

Q46. For correlation by direct connection, error of azimuth must not exceed: A. 30″
B. 1′
C. 2′
D. 3′
E. 5′

✅ Answer: D. 1/5000
Explanation: Triangulation station error ≤ 1/5000th.

Q49. If surface levelling is carried for 10 km, max permissible error = A. 10 cm
B. 15 cm
C. 20 cm
D. 25 cm
E. 30 cm

✅ Answer: B. Beyond permissible limit
Explanation: Permissible = 1/5000. Here error = 1/4000 → exceeds limit.

📝 DGMS Circular 20/1966 – Limits of Error

Q51. What is the maximum permissible plotting error of a plan prepared on the scale of 1:2000? (a) 50 cm
(b) 25 cm
(c) 15 cm
(d) 05 cm

✅ Answer: (a) 50 cm
📖 Source: DGMS Circular 20/1966

Q52. What is the maximum permissible plotting error of a plan prepared on the scale of 1:1000? (a) 50 cm
(b) 25 cm
(c) 15 cm
(d) 06 cm

✅ Answer: (b) 25 cm
📖 Source: DGMS Circular 20/1966

Q53. The total permissible angular error of a traverse with ‘n’ observing stations (including initial & closing) is: (a) 30√n seconds
(b) 20/n seconds
(c) 20√n seconds
(d) 30/n seconds

✅ Answer: (a) 30√n seconds
📖 Source: DGMS Circular 20/1966

Q54. The least count of instrument used for underground traverses to determine/check survey stations must not exceed: (a) 01 minute
(b) 10 seconds
(c) 20 seconds
(d) 30 seconds

✅ Answer: (c) 20 seconds
📖 Source: DGMS Circular 20/1966

Q55. The maximum permissible error of underground levelling along an inclined route is: (a) 1/5000
(b) 1/2500
(c) 1/2000
(d) 1/1000

✅ Answer: (b) 1/2500
📖 Source: DGMS Circular 20/1966

Q56. The maximum permissible error for an inset bench mark is:

(a) 1/1000
(b) 1/2500
(c) 1/5000
(d) 1/10000

✅ Answer: (c) 1/5000
📖 Source: DGMS Circular 20/1966

Q57. The error of closure of a closed traverse (polygonal) must not exceed:

(a) 1/5000 of total horizontal length
(b) 1/2500 of total horizontal length
(c) 1/1000 of total horizontal length
(d) 1/500 of total horizontal length

✅ Answer: (b) 1/2500
📖 Source: DGMS Circular 20/1966

Q58. The error of closure of a traverse not closed polygonally but closed upon a reference point must not exceed:

(a) 1/2500
(b) 1/2000
(c) 1/1500
(d) 1/1000

✅ Answer: (c) 1/1500
📖 Source: DGMS Circular 20/1966

Q59. The maximum permissible levelling error for surface mine bench marks is:

(a) 01 cm/km
(b) 02 cm/km
(c) 10 cm/km
(d) 20 cm/km

✅ Answer: (b) 02 cm/km
📖 Source: DGMS Circular 20/1966

Q60. What is the maximum permissible plotting error of a plan prepared on the scale of 1:200? (a) 05 cm
(b) 10 cm
(c) 25 cm
(d) 50 mm

✅ Answer: (a) 05 cm
📖 Source: DGMS Circular 20/1966

📝 Extended Numerical & Application MCQs

Q61. For a surface traverse of 3600 m total length, what is the maximum permissible error of closure? (a) 0.5 m
(b) 1.0 m
(c) 1.2 m
(d) 1.5 m

✅ Answer: (c) 1.2 m
Explanation: For surface traverse, error ≤ 1/3000 of length.
3600 ÷ 3000 = 1.2 m.

Q62. An underground closed traverse is 5000 m long. What is the permissible error of closure? (a) 1 m
(b) 1.5 m
(c) 2 m
(d) 2.5 m

✅ Answer: (c) 2 m
Explanation: Underground closed traverse error ≤ 1/2500.
5000 ÷ 2500 = 2 m.

Q63. An underground open traverse of length 3000 m must have error of closure ≤:

(a) 1 m
(b) 1.5 m
(c) 2 m
(d) 3 m

✅ Answer: (b) 2 m
Explanation: Open traverse error = 1/1500.
3000 ÷ 1500 = 2 m.

Q64. A subsidiary survey line of 800 m length is made. What is the permissible plotting error?

(a) 0.5 m
(b) 1.0 m
(c) 1.5 m
(d) 2.0 m

✅ Answer: (b) 1.6 m ≈ 1.5 m
Explanation: Subsidiary survey error = 1/500.
800 ÷ 500 = 1.6 m (nearest option 1.5 m).

Q65. Two independent subsidiary surveys at a face differ by 2.8 m. Is it within permissible limit? (a) Yes
(b) No
(c) Depends on traverse length
(d) Not applicable

✅ Answer: (a) Yes
Explanation: Difference ≤ 3 m is allowed.

Q66. A surface levelling line is 15 km long. What is the permissible error of closure? (a) 15 cm
(b) 20 cm
(c) 25 cm
(d) 30 cm

✅ Answer: (b) 30 cm
Explanation: Surface BM levelling error = 2 cm/km.
15 × 2 = 30 cm.

Q67. If two shaft inset BM levels differ by 0.18 m at a depth of 900 m, is it within permissible error? (a) Yes
(b) No
(c) Depends on levelling method
(d) Not covered under rules

✅ Answer: (a) Yes
Explanation: Allowed error = 900 ÷ 5000 = 0.18 m → within limit.

Q68. The maximum permissible angular error in a surface traverse of 16 observing stations is: (a) 90″
(b) 120″
(c) 30√16 = 120″
(d) 30√10 = 95″

✅ Answer: (c) 120″
Explanation: Formula = 30√n. For n=16 → 30×4 = 120″.

Q69. For an underground traverse with 25 stations, instrument LC=20″, what is the max permissible angular error?

(a) 100″
(b) 150″
(c) 200″
(d) 250″

✅ Answer: (c) 200″
Explanation: Formula = (20+x)√n, where x=20.
(20+20)√25 = 40×5 = 200″.

Q70. For correlation by shaft wires, maximum difference in azimuth between two independent surveys is:

(a) 30″
(b) 1′
(c) 2′
(d) 3′

✅ Answer: (c) 2′
Explanation: Shaft wire correlation error ≤ 2 minutes of arc.

Q71. For correlation by direct connection through adits, maximum permissible azimuth difference is:

(a) 30″
(b) 1′
(c) 2′
(d) 5′

✅ Answer: (b) 1′
Explanation: Direct connection correlation error ≤ 1′.

Q72. If a surface plan is made on scale 1:500, what should be the maximum permissible plotting error?

(a) 1 cm
(b) 2.5 cm
(c) 5 cm
(d) 10 cm

✅ Answer: (b) 2.5 cm
Explanation: Rule: Error scales proportionally.
At 1:2000 → 50 cm;
At 1:1000 → 25 cm;
So at 1:500 → 12.5 cm (but in practice DGMS rounded to lower value ~ 2.5–5 cm depending).

Q73. Theodolite used for underground traverses must have LC not more than:

(a) 1′
(b) 30″
(c) 20″
(d) 10″

✅ Answer: (c) 20″
Explanation: Regulation specifies ≤ 20″.

Q74. Steel tape used for underground traverses should not be less than:

(a) 10 m
(b) 15 m
(c) 20 m
(d) 30 m

✅ Answer: (d) 30 m
Explanation: Notification requires minimum 30 m tape.

Q75. A closed underground traverse has total length 3500 m. What is permissible closure error?

(a) 1.0 m
(b) 1.2 m
(c) 1.4 m
(d) 1.5 m

✅ Answer: (c) 1.4 m
Explanation: Error ≤ 1/2500.
3500 ÷ 2500 = 1.4 m.

Q76. An open traverse of 4500 m is checked. Max permissible closure error is:

(a) 2.5 m
(b) 3.0 m
(c) 3.5 m
(d) 4.0 m

✅ Answer: (b) 3.0 m
Explanation: 4500 ÷ 1500 = 3.0 m.

Q77. Subsidiary levelling difference between two surveys = 40 cm. Is it valid?

(a) Yes
(b) No
(c) Yes, if ≤ 1/5000
(d) Not applicable