Stone Arch Viaduct / Bridge

I've included both names as I have seen folks address them with either name. I think what I am trying to create is principally a viaduct, but yesterday I inserted a bridge in a portion of it. I did it in a straight track portion, so I could alternately allow for it to be included in the final trackwork, or perhaps not.

I've had some forum members suggest that I am trying to 'monopolize' a forum discussion by placing multiple postings on it in succession. I wish to explain my actions so you might understand why I do such things in a number of incidents.

And ask each of you if you've run into the same situation?

Good morning.

Would like to "build" a small "mom and pop" gravel pit set in the 1940/1960 era time frame on a midwestern HO layout.

Unable to locate an HO scale Steam Shovel or similar to load gravel and sand, etc. into gons and/or hoppers.

I'll buy a Proto Throttle relatively soon based on the great feedback I've seen here on the forums.  Tim Garland had written an article addressing a number of custom settings including momentum and deceleration curves.  What I can't seem to find is mid- and max-speed settings. 

What have others found to be good speed settings?  Are you doing min/mid/max or a custom curve?  What values are you using?

i'm trying to get to the most prototypical settings and would appreciate any help anyone can offer.

-Eric