1, first open the drawing software such as CAD, create a new picture, draw the shape of the bridge according to the actual situation, and select the "rotation" tool on the symbol toolbar.

2. Secondly, choose the position that needs to be marked up and down in the picture, and draw three rectangles with the mouse, namely an upper rectangle and two lower rectangles. In the drawn symbol, move the middle rectangle up and down to determine the up and down direction of the bridge, and then rotate it to the same direction as the bridge.

3. Finally, place the symbol in the front view of the bridge, and you can add text comments to the symbol to show the meaning and direction.