設計例: 設計データを使用した曲線の設定

Consider that a civil engineer has to plot a simple horizontal curve with a 200-meter radius and a 20-degree intersection angle in the field.

The engineer uses the method of perpendicular offsets from the long chord to plot the curve. 

First, the long chord length is calculated as 69.46 meters, and the intervals for perpendicular offsets are set at 3 meters.

Next, the offset expression at the midpoint is used to determine the ordinate of the long chord’s center, and to ensure accuracy, this value is verified against the middle ordinate of the curve.

The engineer marks the long chord of the curve on the ground, and the points at 3-meter intervals along both sides of the midpoint are marked.

Then, the expression for the offset distance is used to calculate the perpendicular offsets, which are marked along the long chord at the corresponding points.

Finally, the engineer connects the top ends of the perpendicular offsets to form the curve.