# How do you call a map that shows the characteristics of a train tunnel (3D) in paper (2D)?

I have googled for a while and I can't seem to find the correct term to refer to this.

Imagine you have a tunnel in where trains, cars, or anything goes through.

This tunnel might elements along its extension, such as cracks, fissures, weak spots, etc. To visualize this in paper, a 3D figure must be "projected" into 2D.

I'm looking for the word to refer to this kind of map.

The closest I've come to is calling it "A projection map" but is there a more suitable term for this?

In japanese it can be called a "展開図(てんかいず) Tenkaizu", but a dictionary translation, or a google translation don't fit since that term is also used to describe the diagrams of how to fold paper to build something. (like a cube)

I tried in the "English" site, but I was referred to this site instead.

• Orthographic projection comes to mind. Sep 2 '18 at 14:20

An engineering drawing that shows a curved surface "unwrapped" onto a plane is called a development.

This is commonly used in sheet metal working, where making the object follows the reverse process - you cut out the correct shape(s) on a flat sheet of material and then bend them into the correct 3-D form(s) and join them together.

See http://nptel.ac.in/courses/112103019/36 for some examples - google will find plenty more.

In engineering drawing, a projection is "what you would see if you looked at the object from a long distance away, through a telescope" which is not what your example shows.

• I think that it might be surface development. Jul 24 '17 at 11:33
• +1 Putting "tenkaizu" in google translate offers either "exploded view" or "development view". Jul 24 '17 at 15:45
• I had noticed schematics of how to build cubes, or figures with papers came out. I just didn't know the inner layout of a tunnel's roof could be expressed using something usually meant for children to build paper figures. Guess it was simpler than i thought. Thanks! Jul 25 '17 at 0:40

The type of drawing you mentioned is common for a number of underground mines.

Surveyors produce the overall outline of the tunnel & then geologists manually drawn on the geological features and structures. Such drawings are produced on an ongoing basis, as tunnels are extended.

Generally, they are referred to as maps of the walls & backs. Backs being the term for the ceiling or roof of a tunnel. Civil engineers may use the term ceiling or roof.

The term you seek may vary between industries such as civil and mining, but as you state a project map would suffice. If you want to be more specific, you can call it a projection map of the walls and ceiling.

Not quite sure which kind of map you want. A "projection" is certainly a valid option.
You might also be thinking of a "plan view" which is simply the X-Y layout of the tunnel, ignoring vertical behaviors. A plan view is more typically used to look at the layout of a building floor-by-floor, showing object locations (walls, doors, etc).

• I don't think "plan view" is appropriate: the left hand part includes the walls, which are vertical. Jul 24 '17 at 14:49

Within the tunnelling environment I work in we refer to that sort of image as a 'developed elevation'.