Vertical Alignment

This section deals with the vertical alignment of the road which includes vertical gradients and vertical curves.

Gradient

The gradient is the rate of rise or fall along the length of the road with respect to the horizontal plane. On long and steep upgrades, a speed reduction is expected, especially for heavy commercial vehicles. You need to be extra careful in terms of selection of speed and manoeuvre (say, overtaking) while driving on a gradient. Also, on the undivided road with two-way traffic movements, priority should be given to vehicles that are on the upgrade as stopping and restarting of vehicles is difficult on upgrade.

Vertical Curves

Figure: Summit Curve

Figure: Summit Curve

Figure: Valley Curve

Figure: Valley Curve

Vertical curves are of two types, namely-summit curve and the valley curve. On the summit curve, the sight distance may be restricted. So, you need to control your speed and also avoid overtaking in such a situation on an undivided road with two-way traffic movements. While driving on an upgrade of a valley curve during nighttime, only the length of the road illuminated by headlights is visible to you. In this case, also, you should restrict your speed, avoid overtaking and drive carefully as the sight distance is limited.