- 2080 Chaitra · 6 marks
Transition curve 6°, Ls=90 m, chainage 13+700
Short answer
Δ = 40°, R = 286.48 m. Transition shift s = 1.178 m, total tangent Ts = 149.70 m, circular length Lc = 110.00 m. First two transition deflections at TS: 0°02′05″ and 0°08′37″; circular at SC: 0°58′11″ and 3°58′11″.
Two tangents T₁V and T₂V intersect at chainage of 13+700 km. The bearing of T₂V is 300°30' and T₁V is 80°30'. It is proposed to insert 6° circular curve with transition curve 90 m at each end. Calculate the first two deflection angle for setting out first transition and circular curve only at peg interval of 10 m on transition curve and 30 m at circular curve.
Deflection angle between the tangents
Bearing of T₁V (travelling towards V) . Bearing of T₂V is observed from T₂ towards V, , so the forward direction of travel from V to T₂ is .
Radius and transition elements
6° curve with a 30 m arc: m. m.
Chainage of V m (13+700 km).
| Point | Chainage (m) |
|---|---|
| TS = V − T_s | 13550.30 |
| SC = TS + 90 | 13640.30 |
| CS = SC + L_c | 13750.30 |
| ST = CS + 90 | 13840.30 |
First two deflection angles
Transition curve (theodolite at TS), minutes, points at multiples of 10 m:
| Point (chainage, m) | l (m) | α (min) | α |
|---|---|---|---|
| 13560.00 | 9.70 | 2.09′ | 0°02′05″ |
| 13570.00 | 19.70 | 8.62′ | 0°08′37″ |
Circular curve (theodolite at SC), minutes, points at multiples of 30 m:
| Point (chainage, m) | Chord c (m) | δ | Cumulative |
|---|---|---|---|
| 13650.00 | 9.70 | 0°58′11″ | 0°58′11″ |
| 13680.00 | 30.00 | 3°00′00″ | 3°58′11″ |
Answer: transition: 0°02′05″ and 0°08′37″; circular: 0°58′11″ and 3°58′11″.
✓ Answer checked by Claude Opus 5.5 (high effort)
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