Talk:Fundamentals of Transportation/Sight Distance

The initial equations on this page are fundamentally wrong. The angle is irrelevant to the friction force which is already in line with direction the vehicle is travelling. The correct force on the vehicle in its direction of travel is: $$ F = W\left( {\sin \left( \theta \right) - f} \right) \,\!$$

where f is the braking efficiency. In general, the friction force is on the brakes and not between the road and the tyre. Therefore the force on the road is only relevant if the tyres have locked.

Where did the 0.278 factor come from?
Where did the 0.278 factor come from when deriving expression for the stopping sight distance? This isn't immediately clear from the derivation. This factor was seen in the given expression

$$ d_s = 0.278t_r v_i + \frac $$

--TinyThaiTiger (discuss • contribs) 21:52, 8 February 2019 (UTC)