Bridges, especially overpass models, differ from railways as they are three-dimensional rather than flat. To create an interlocking sense of depth, primarily colors, contour lines, and shapes are used. There are two main methods: the three-dimensional method and the flat method. The flat method is typically used when the bridge is an accessory. To showcase the bridge itself, the three-dimensional method is generally employed, as it clearly displays the size and height of the bridge. Specific techniques include:

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

2. Width and Narrowness Representation: During the construction of a bridge, one can utilize visual errors to differentiate its width, rather than aiming for proportional reduction. Instead, certain widths can be intentionally widened, allowing the constructed bridge to visually convey the distinction between widths.

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

4. Fixed Model: The finished model must be securely fastened to the base platform, allowing for piecemeal gluing. This ensures that no single section is too long and that the joints are reinforced, guaranteeing the stability of the model.