flickering green train



This is a flickering green train I build with shadertoy.
To see the code in shadertoy: https://www.shadertoy.com/view/WttXzs
I want trace back to green train times. Staring at the sky, I don’t understand where is destination. Actually, in old times, green train is signal of news. All news will come with green train. My father has been admitted to the university, which is really a great news in his times. He sometimes take me to the railway to see the trains passing by, telling me that these trains carrying his admission letter to him. The green train hold more than news. So I want to make a flickering train. The rest of the time, it is the days waiting for something on a train that will hopefully stop for somebody.
Technically, I am just coding lines, rectangles and 2D noise and composing them in my ideal way. A problem is that the fan of my GPU is turning on.