Bernard Kempinski (web site: http://usmrr.blogspot.com/) has done quite a bit of research on the USMRR - there are some possible track plans for City Point in his book "Mid-size track plans for realistic layouts".
Maybe worth checking out.
Stein
The Library of Congress web site (http://www.loc.gov) has photos and railroad maps from that era in their American Memory section, which may provide some of the information you are seeking.
Kanahwa,
I suggest visiting the yahoo group Civil War Railroads. There are 2 members in particular who model O and N scales. The members there are also quite helpful.
TR
On the subject of City Point, be sure to check out the You Tube videos of the Other Great Locomotive Chase. Fictional of course, but a great story and very well told.
https://www.youtube.com/watch?v=Tj1Nk4NmuUw
or search on:
Great Fun,
Kevin
I just acquired "Mr. Lincoln's Military Railroads" (1979) by Roy and Arthur
Meredith. Published by W.W. Norton & Company. It is 253 pgs. of great detail
on Civil War R.R.'s (North) with photos, drawings and information. Coverage of
City Point starts on pg. 178 thru last mention on pg. 218 with the abondonment
of Richmond. The authors mention in "sources" that "General Horace Porter's
description
Sorry for the partial message (not good at this).
See www.willeagal.net/railroad for a plan on an H.O. rr of City Point.
Also there's a City Point Historical District with a web site.
Lloyd