Q:

8 Train Stations

You are going to build $8$ train stations and the railroads with it in an area. But you are asked to build these stations and their railroads in a very efficient way where there has to be the least number of intersection points on the railroad for the safety and most relaxed schedule and these all stations are also needed to be connected directly to each other as well. So; 

What is the minimum number of crossing points possible? Draw a map of your solution.

Do not forget, only two railroads can intersect at the same point, otherwise it will not be safe at all passing more than two trains at the same point!
For example if this question was asked for 4 stations, the answer will be $0$ as shown below:

A:

 Basically you are asking what the crossing number is of the complete graph with 8 nodes. Below is a picture taken from the online book, Handbook of Graph Drawing and Visualization, chapter 2. The crossing number, i.e. the minimum number of crossings, is 18.
 

