D&RGW Gas/Oil Pipe questions

I've been looking around in my various sources but just can't seem to find a general answer, so maybe someone here might be able to help.

I'm trying to figure out the typical number of drill pipe (the smaller diameter pipe) that would be carried in each pipe gondola. I'd like to know since I'm currently building two pipe gondolas for my train layout.

But it's hard looking at prototype photos and trying to figure out how many of the smaller pipes were typically held.

The pipe size that looks good to my eye in our compressed scale is 3/16" diameter by 20" long.

Also how were these pipe stacked?

Like a pyramid shape? Meaning most pipes at the bottom and loosing one pipe each row as they go up. Kind of looks like this judging by a few photos I've looked at. And it also looks like they were strapped together.

Any help is appreciated.

Matt
Lake Forest, CA
Click Here for my model train photo website