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Rankine's table, IP 2+450 km, 30°, 3° curve

Short answer

Using D = 3° for a 25 m arc, R = 477.46 m, T = 127.94 m, L = 250.00 m. Chainages: T1 = 2322.06 m, T2 = 2572.06 m. Deflection angles δ = 1718.87c/R are tabulated; final check is Δ/2 = 15°00′00″.

The chainage of IP is 2+450 km. Deflection angle is 30°. The curve is 3° with the fixed arc length of 25 m. The peg interval is 30 m. Calculate the setting out table by Rankine's deflection angle method.

Chainage of IP =2+450= 2+450 km =2450= 2450 m, Δ=30∘\Delta = 30^\circ, degree of curve D=3∘D = 3^\circ for a fixed arc of 25 m, peg interval 30 m.

Elements

R=180 CπD=180×25π×3=477.46 mT=Rtan⁡15∘=127.94 mL=πRΔ180=250.00 mCh. T1=2450−127.94=2322.06 mCh. T2=2322.06+250.00=2572.06 m\begin{aligned} R &= \frac{180\,C}{\pi D} = \frac{180\times 25}{\pi\times 3} = 477.46\ \text{m}\\ T &= R\tan 15^\circ = 127.94\ \text{m}\\ L &= \frac{\pi R\Delta}{180} = 250.00\ \text{m}\\ \text{Ch. T}_1 &= 2450 - 127.94 = 2322.06\ \text{m}\\ \text{Ch. T}_2 &= 2322.06 + 250.00 = 2572.06\ \text{m} \end{aligned}

Setting-out table (theodolite at T₁)

δ=1718.87 c/R\delta = 1718.87\,c/R minutes:

Point (chainage, m)Chord c (m)δ = 1718.87c/RCumulative deflection
2322.06--0°00′00″
2340.0017.941°04′34″1°04′34″
2370.0030.001°48′00″2°52′34″
2400.0030.001°48′00″4°40′34″
2430.0030.001°48′00″6°28′34″
2460.0030.001°48′00″8°16′34″
2490.0030.001°48′00″10°04′34″
2520.0030.001°48′00″11°52′34″
2550.0030.001°48′00″13°40′34″
2572.0622.061°19′26″15°00′00″

Check: final deflection =Δ/2=15∘00′00′′= \Delta/2 = 15^\circ00'00'' (computed 15°00′00″).

Answer: R=477.46R = 477.46 m, T=127.94T = 127.94 m, L=250.00L = 250.00 m, T₁ = 2322.06 m, T₂ = 2572.06 m; deflection angles as tabulated.

✓ Answer checked by Claude Opus 5.5 (high effort)

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