Bridges, especially flyover models, differ from railways as they are not flat but three-dimensional. Therefore, to create an interlocking sense of depth, color shades, contour lines, and shapes are primarily employed. There are two main methods: the three-dimensional production method and the flat production method. The flat production method is usually used when bridges are accessories. To showcase the bridge itself, the three-dimensional production method is generally preferred, as it clearly demonstrates the size and elevation of the bridge. The specific methods are as follows:

1. Hierarchical Representation: Display the height, dimensions, and levels of the bridge using contour lines. During painting, the color transitions from light to dark from top to bottom, and shadow effects are created for a more realistic visual appearance.

2. Width Representation: During the construction of bridges, the width can be accentuated using visual illusions, rather than strictly scaling down proportionally. By intentionally enlarging certain widths, the resulting bridge will visually convey the distinction between narrow and wide.

3. Perspective Representation: As we usually view models from above, the green belts and guardrails on both sides of the bridge should be made taller to avoid them being obscured.

4. Fixed Model: Once the model is completed, it should be securely fastened to the base platform. Therefore, the gluing process can be done in sections, ensuring each segment is not overly long, and reinforcing the joints for stability.