Bridge Structure are usually (always) set out using scale factor one.
What are different kinds of scale models
You can build a scale model/toy bridge out of toothpicks. You can not build a real bridge to walk on out of toothpicks.
The 'scale' of a guitar refers to the average string length between the bridge and the nut of the guitar (this is the average length because intonation at the bridge means that not all the strings are identical in length from nut to bridge).
The bridge design was based on New York's Hells Gate Bridge
5.1 cm
I believe this means that the length of the strings between the nut and the bridge is 24.75 inches.
It is based mostly on opinion, there is no set scale as such. To you a bridge that has fallen might be an 8 on the mercalli scale, but to somebody else it may only be a 7. Also it varies depending on the surroundings you are in e.g. urban or rural.
On any bass - acoustic or electric - the scale length is the distance from the nut at the top of the fretboard to the bridge or bridge saddle. The "A" string is usually used to make the measurement. I can't speak for acoustic bass, but bass guitars commonly come in two scale elngths: "short" (30", some manufacturers use 31") and "long" (34"),
The standard full size is called "Long Scale" or "34 in. scale", meaning that the strings measure 34 in from nut to bridge. Medium scale is between 30 and 33 in. Short scale is anything shorter than 30 in. If your fingers aren't long enough to play a long scale bass, try a medium or short scale bass.
It depends on the scale of the model
A full scale map of a city would be totally useless since you would require an area as large as the city to open it up! Similarly, a full scale plan of a large building would be a pointless waste of paper.