Nirmaanpro
Advertisement Advertise your business here Reach civil engineering students and professionals across India · contact@nirmaanpro.shop

RailPro › Track & permanent way

RailPro · Track & permanent way

Curves, cant & curve realignment — questions with answers

42 questions on curves, cant & curve realignment, each with the answer and where it comes from. Try each one before you tap Show answer.

Take these as a scored test

Answer them against the clock and see your score with every answer explained.

Start set 1 Start set 2

Questions

Q1.Of the three formulae for the desirable transition length, the one based on the cant gradient (twist) is ______

  1. L = 0.72 Ca
  2. L = 0.008 Ca·Vm
  3. L = 0.008 Cd·Vm
  4. L = 4.4 √R
Show answer

Answer: (A) L = 0.72 Ca

L3 = 0.72 Ca comes from the 1 in 720 cant gradient. L1 and L2 (0.008 Ca·Vm and 0.008 Cd·Vm) come from the rate of change of cant and cant deficiency.

Source: RailPro e-book Vol 1, page 586

Q2.According to the first principle of string lining, slewing one station on a curve changes the versines at the two adjoining stations by ______

  1. The same amount, in the same direction
  2. Twice the amount, in the opposite direction
  3. Half the amount, in the opposite direction
  4. Half the amount, in the same direction
Show answer

Answer: (C) Half the amount, in the opposite direction

The first principle: a slew at one station changes the versines at the two adjacent stations by half that amount in the opposite direction.

Source: RailPro e-book Vol 1, page 698

Q3.Track mounted automatic Gauge Face Lubricators should be provided on curves of radius _____ m and sharper to reduce rail gauge face wear.

  1. 875
  2. 1750
  3. 1000
  4. 583
Show answer

Answer: (A) 875

Source: JE (P.Way) Question Bank 2025, Q.1785

Q4.On curves laid with fish-plated joints, cut rails are inserted when the inner-rail joint leads the outer-rail joint by ______

  1. The full pitch of the bolt holes
  2. 25 mm
  3. Half the pitch of the bolt holes
  4. One fish-plate length
Show answer

Answer: (C) Half the pitch of the bolt holes

When the inner rail leads by half the bolt-hole pitch, a cut rail (shorter by one pitch) is used to bring the joints square again.

Source: RailPro e-book Vol 1, page 611

Q5.Using the relation D = 1750/R, what is the radius of a 2° curve?

  1. 437.5 m
  2. 1750 m
  3. 3500 m
  4. 875 m
Show answer

Answer: (D) 875 m

R = 1750/D = 1750/2 = 875 m.

Source: RailPro e-book Vol 1, page 545

Q6.On new lines or complete renewals, BG curves of radius less than 350 m may be laid to a gauge of up to ______

  1. 1676 mm (no widening)
  2. 1679 mm
  3. 1696 mm
  4. 1686 mm
Show answer

Answer: (D) 1686 mm

At laying, curves sharper than 350 m may be laid with up to +10 mm (1686 mm). Straights and flatter curves are laid to −5 mm/+3 mm.

Source: RailPro e-book Vol 1, page 633

Q7.On a non-transitioned BG curve, cant is run out over the virtual transition. At the maximum cant gradient of 1 in 360, about how much cant can be provided?

  1. 20 mm
  2. 65 mm
  3. 75 mm
  4. 40 mm
Show answer

Answer: (D) 40 mm

The virtual transition equals the bogie-pivot distance (14.785 m on BG). At 2.8 mm/m this gives about 14.7 × 2.8 ≈ 40 mm.

Source: RailPro e-book Vol 1, page 591

Q8.The IRPWM formula for the safe speed (kmph) on a transitioned BG curve is ______

  1. V = 0.27 √(R·Ca)
  2. V = 0.27 √[R(Ca + Cd)]
  3. V = 4.4 √(R − 70)
  4. V = 0.27 √[R(Ca − Cd)]
Show answer

Answer: (B) V = 0.27 √[R(Ca + Cd)]

Safe speed V = 0.27 √[R(Ca + Cd)], with R in metres and the cants in mm.

Source: RailPro e-book Vol 1, page 617

Q9.For a reverse curve with no straight between the two curves, the transition length based on the rate of change of cant is ______

  1. 0.008 (Ca1 + Ca2)·Vm
  2. 0.008 (Ca1 − Ca2)·Vm
  3. 0.72 (Ca1 − Ca2)
  4. 0.008 Ca1·Vm
Show answer

Answer: (A) 0.008 (Ca1 + Ca2)·Vm

For reverse curves the cants add up, so L1 = 0.008 (Ca1 + Ca2)·Vm. This does not apply when a straight separates the curves.

Source: RailPro e-book Vol 1, page 597

Q10.The extra clearance needed on curves because of lean due to superelevation is ______

  1. L = G·Ca/H
  2. L = H·Ca/G
  3. L = H·G/Ca
  4. L = Ca/(H·G)
Show answer

Answer: (B) L = H·Ca/G

Lean L = H·Ca/G. H is the height of the structure or the maximum vehicle height, whichever is less, and G is the gauge.

Source: RailPro e-book Vol 1, page 642

Q11.On Group A and B routes, the minimum straight to be kept between the transitions of two reverse curves is ______

  1. 20 m
  2. 30 m
  3. 50 m
  4. 100 m
Show answer

Answer: (C) 50 m

A straight of at least 50 m is required. Shorter straights should be eliminated by extending the transitions.

Source: RailPro e-book Vol 1, page 651

Q12.Centre to centre distance of bogies in BG/ ICF coaches is ______________

  1. 21.34 m
  2. 14.785 m
  3. 14.90 m
  4. 3.350
Show answer

Answer: (B) 14.785 m

Source: JE (P.Way) Question Bank 2025, Q.1795

Q13.In curves the excess length ‘d' by which the inner rail gains over the outer rail is calculated by the formula

  1. L x G / R
  2. G x R / L
  3. L x R / 1750
  4. L x G x R
Show answer

Answer: (A) L x G / R

Source: JE (P.Way) Question Bank 2025, Q.1763

Q14.The equilibrium cant (mm) for a speed V (kmph) on a curve of radius R (m) and gauge G (mm) is ______

  1. G·V²/(127R)
  2. G·V/(127R)
  3. 127·V²/(G·R)
  4. G·V²/(13R)
Show answer

Answer: (A) G·V²/(127R)

Equating the cant component to the centrifugal force gives equilibrium cant SE = GV²/(127R), as per Para 406(a) of the IRPWM.

Source: RailPro e-book Vol 1, page 557

Q15.On routes where rail grinding is practised, track-mounted automatic gauge face lubricators are to be provided on curves of radius ______

  1. 875 m and sharper
  2. 1400 m (1.25°) and sharper
  3. 600 m and sharper
  4. 1750 m (1°) and sharper
Show answer

Answer: (B) 1400 m (1.25°) and sharper

Normally they go on curves of 875 m (2°) and sharper, but on rail-grinding routes on curves of 1400 m (1.25°) and sharper.

Source: RailPro e-book Vol 1, page 627

Q16.The limiting (minimum) radius of curve for Metre Gauge, as per Chapter I of the Schedule of Dimensions, is ______

  1. 109 m
  2. 44 m
  3. 175 m
  4. 218 m
Show answer

Answer: (A) 109 m

The SOD limiting radii are 175 m for BG, 109 m for MG and 44 m for NG.

Source: RailPro e-book Vol 1, page 542

Q17.Maximum cant permitted on B G– Group ‘D' routes is ______ mm.

  1. 145
  2. 115
  3. 140
  4. 165
Show answer

Answer: (D) 165

Source: JE (P.Way) Question Bank 2025, Q.1752

Q18.In IR Designation of a curve is done by

  1. degree
  2. radius
  3. degree or radius
  4. Curvature
Show answer

Answer: (A) degree

Source: JE (P.Way) Question Bank 2025, Q.1731

Q19.The transition curve adopted on Indian Railways is a ______

  1. Clothoid spiral
  2. Lemniscate
  3. Cubic parabola
  4. Simple circular arc
Show answer

Answer: (C) Cubic parabola

IR transitions are cubic parabolas with the equation y = x³/6RL.

Source: RailPro e-book Vol 1, page 578

Q20.For a diamond crossing that cannot be avoided on a BG curve, the speed on the approach curve must in no case exceed ______

  1. 65 kmph
  2. 50 kmph
  3. 40 kmph
  4. 75 kmph
Show answer

Answer: (A) 65 kmph

The Chief Engineer decides the restriction, but it cannot exceed 65 kmph on BG (50 kmph on MG, 40 kmph on NG). The approaches are laid without cant for at least 20 m.

Source: RailPro e-book Vol 1, page 671

Q21.To limit track twist, the normal maximum cant gradient on a transition is ______

  1. 1 in 360
  2. 1 in 720
  3. 1 in 1200
  4. 1 in 500
Show answer

Answer: (B) 1 in 720

Cant gradient is normally limited to 1.4 mm/m (1 in 720). In exceptional cases it can be 2.8 mm/m (1 in 360).

Source: RailPro e-book Vol 1, page 585

Q22.For a turnout of contrary flexure taking off from a curve, the cant on the main line is ______

  1. Ceq(turnout) + 75 mm
  2. 75 mm − Ceq(turnout)
  3. 165 mm − Ceq(turnout)
  4. Equal to Ceq(turnout)
Show answer

Answer: (B) 75 mm − Ceq(turnout)

The turnout side gets negative cant, limited by the 75 mm cant deficiency. So main-line cant Ca = 75 − Ceq of the turnout.

Source: RailPro e-book Vol 1, page 667

Q23.The shift S of a circular curve when a transition of length L is inserted on a curve of radius R is ______

  1. L²/8R
  2. L²/6R
  3. L²/12R
  4. L²/24R
Show answer

Answer: (D) L²/24R

Shift S = L²/24R. It is measured between the original circular curve and the shifted circular curve, not between the straight and the curve.

Source: RailPro e-book Vol 1, page 581

Q24.What is the limit of lateral wear on rails on curves on Group C and D routes?

  1. 6 mm
  2. 8 mm
  3. 12 mm
  4. 10 mm
Show answer

Answer: (D) 10 mm

The lateral wear limit on curves is 8 mm for Group A and B routes and 10 mm for Group C and D routes.

Source: RailPro e-book Vol 1, page 620

Q25.When trains run on a curve at speeds lower than the equilibrium speed (cant excess), the main maintenance problem is ______

  1. Excess wear on the outer rail
  2. Excess wear on the inner rail
  3. Widening of gauge at joints
  4. Loss of ballast on the outer shoulder
Show answer

Answer: (B) Excess wear on the inner rail

With cant excess the centripetal component exceeds the centrifugal force, so the inner rail carries more load and wears more.

Source: RailPro e-book Vol 1, page 569

Q26.In the string lining method, the second summation of the versine difference (proposed − existing) at a station gives ______

  1. Half the slew at that station
  2. The full slew at that station
  3. The proposed versine
  4. The cant to be provided
Show answer

Answer: (A) Half the slew at that station

By the fifth principle, the second summation of the versine difference is half the slew (the half throw), so the slew is twice that value.

Source: RailPro e-book Vol 1, page 708

Q27.Normally, the rate of change of cant or cant deficiency along a transition should not exceed ______

  1. 35 mm/sec
  2. 55 mm/sec
  3. 65 mm/sec
  4. 75 mm/sec
Show answer

Answer: (A) 35 mm/sec

The rate of change of actual cant or cant deficiency is normally limited to 35 mm/sec, and up to 55 mm/sec only in exceptional circumstances.

Source: RailPro e-book Vol 1, page 583

Q28.A combination of two or more circular curves of different radii bending in the same direction is called a ______

  1. Compound curve
  2. Reverse curve
  3. Transition curve
  4. Simple curve
Show answer

Answer: (A) Compound curve

A compound curve combines circular curves of different radii in similar flexure. A reverse curve has curves of contrary flexure.

Source: RailPro e-book Vol 1, page 598

Q29.If the second summation of the versine difference at the last station is positive, how is the correcting couple applied?

  1. Positive correction at the initial stations and negative at the later stations
  2. Negative correction at the initial stations and positive at the later stations
  3. Equal positive correction at all stations
  4. Correction only at the centre of the curve
Show answer

Answer: (B) Negative correction at the initial stations and positive at the later stations

The couple is equal and opposite: a negative correction at the starting stations and a positive one at the later stations makes its second summation negative, cancelling the residual.

Source: RailPro e-book Vol 1, page 722

Q30._______ occurs when at train travels around a curve at a speed higher than the equilibrium speed.

  1. cant excess
  2. cant deficiency
  3. equilibrium cant
  4. None
Show answer

Answer: (B) cant deficiency

Source: JE (P.Way) Question Bank 2025, Q.1742

Q31.Maximum degree of curve permitted for BG is ______________

  1. 8 degree
  2. 10 degree
  3. 9 degree
  4. 7 degrees
Show answer

Answer: (B) 10 degree

Source: JE (P.Way) Question Bank 2025, Q.1679

Q32.The value by which actual cant falls short of equilibrium cant is known as

  1. Cant deficiency
  2. cant
  3. offset
  4. shift
Show answer

Answer: (A) Cant deficiency

Source: JE (P.Way) Question Bank 2025, Q.1700

Q33.A curve must be realigned within a month if the station-to-station versine variation exceeds the service limits at more than ______ of the stations

  1. 10%
  2. 20%
  3. 25%
  4. 50%
Show answer

Answer: (B) 20%

If the limits are exceeded at more than 20% of stations, the curve is realigned within a month. If only a few stations are affected, local adjustment is done.

Source: RailPro e-book Vol 1, page 689

Q34.What is the versine on a 20 m chord for a 4° curve?

  1. 28.57 mm
  2. 57.14 mm
  3. 114.28 mm
  4. 228.56 mm
Show answer

Answer: (C) 114.28 mm

R = 1750/4 = 437.5 m and V = C²/8R = 20²/(8 × 437.5) m = 114.28 mm.

Source: RailPro e-book Vol 1, page 547

Q35.Gradient of 1 in 200 can be written in terms of percentage as _________

  1. 0.05 %
  2. 5 %
  3. 2%
  4. 0.5 %
Show answer

Answer: (D) 0.5 %

Source: JE (P.Way) Question Bank 2025, Q.1773

Q36.On BG, check rails are to be provided on curves of ______

  1. 8° and above
  2. 4° and above
  3. 5° and above
  4. 10° only
Show answer

Answer: (A) 8° and above

As per Chapter 1 of the BG SOD, check rails are provided on curves of 8° and above with a minimum clearance of 44 mm.

Source: RailPro e-book Vol 1, page 624

Q37.Chord length for measuring versine at curves is _________ mts.

  1. 6
  2. 10
  3. 12
  4. 20
Show answer

Answer: (D) 20

Source: JE (P.Way) Question Bank 2025, Q.1689

Q38.The grade compensation on a 4˚ curve on a Broad Gauge railway track is

  1. 0.20%
  2. 0.16%
  3. 0.12%
  4. 0.08%
Show answer

Answer: (B) 0.16%

Source: JE (P.Way) Question Bank 2025, Q.1710

Q39.What is the maximum cant permitted on BG Group A, B and C routes as per the IRPWM?

  1. 140 mm
  2. 185 mm
  3. 150 mm
  4. 165 mm
Show answer

Answer: (D) 165 mm

The IRPWM limits actual cant to 165 mm on Group A, B and C routes.

Source: RailPro e-book Vol 1, page 560

Q40.On routes with speeds above 100 kmph, the maximum cant deficiency allowed for nominated stock with the permission of the PCE is ______

  1. 100 mm
  2. 75 mm
  3. 125 mm
  4. 165 mm
Show answer

Answer: (A) 100 mm

Cant deficiency may go up to 100 mm for nominated stock on routes faster than 100 kmph with the PCE's permission; for all others it is 75 mm.

Source: RailPro e-book Vol 1, page 566

Q41.What is the maximum cant excess permitted as per the IRPWM?

  1. 50 mm
  2. 100 mm
  3. 75 mm
  4. 165 mm
Show answer

Answer: (C) 75 mm

Cant excess is limited to 75 mm, worked out for the booked speed of goods trains.

Source: RailPro e-book Vol 1, page 570

Q42.Chord length for measuring lead curvature of a turnout is

  1. 5 m
  2. 6 m
  3. 7.5m
  4. 7 m
Show answer

Answer: (B) 6 m

Source: JE (P.Way) Question Bank 2025, Q.1721

‹ SWR, LWR/CWR, welding, USFD & rail fracturesAll RailPro topicsPoints & crossings (turnouts) ›

Preparing for AE / JE exams?
Get new civil engineering vacancies on Telegram, posted automatically every day. Free to join.
Join on Telegram ›