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Based on the given information, the safe overtaking speed can be calculated as follows:
- Design speed (Vd) = 96 km/h
- Speed of vehicle to be overtaken (Vo) = (5/6) x Vd = 80 km/h
- Reaction time (Tr) = 2 seconds
- Overtaking sight distance (D) = 3 x (Vd + Vo) x Tr = 3 x (96 + 80) x 2 = 912 meters
- Safe overtaking speed (Vs) = D / Time taken to cover D at the design speed
- Time taken to cover D at the design speed = D / Vd = 912 / 96 = 9.5 seconds
- Therefore, Vs = 912 / 9.5 = 96 km/h
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Therefore, the safe overtaking speed for a design speed of 96 km/h, assuming a vehicle to be overtaken at a speed of 5/6 times design speed and reaction time of 2 seconds, is 96 km/h.