I am looking for a total list of the "Davis Formulas". It is a list of
equasions compiled by W. A. Davis in 1927 pertaining to the
performance of trains compared to friction, track curve, track slope,
wind resistance, etc. I am especially interested in information on the
changes to the formulas since 1927 to reflect the properties of
locomotives and freight cars from 1970 to the present day.

As an option to this specific question, I would take recommendations
on a self-teaching, READER FRIENDLY book on physics books that might
be applied to railroads (is there such a thing as "mechanical
physics"?), as
long as the book recommended is NOT "The Railroad - What it is, What
it Does" by Jonh H. Armstrong. I already have that book, and the
formulas are incomplete. For instance, they address train speed given
horsepower and tonnage, but there are no formulas to calculate the
loss of speed when horsepower is insufficient.

The initial article in which Davis laid out his formulas was entitled,
"The tractive resistance of electric locomotives and cars," and it
appeared in the periodical "General Electric Review" in 1926, volume
29. Archives of the "General Electric Review" can be found in many
major academic libraries, or copies of back articles can be ordered
through IEE at a cost of 4 pounds for IEE members and 10 pounds for
non-members.  For ordering details, see:
http://www2.iee.org/cgi-bin/period-sar.cgi?form_type=fields&any=1318020404132514&order=Closeness+of+Match


There is a fabulous doctoral thesis by Piotr Lukaszewicz of the Royal
Institute of Technology in Stockholm, entitled, "Energy consumption
and running time for trains: modelling of running resistance and
driver behaviour based on full-scale testing"; published in 2001, this
work references the Davis article and has several sections that
address your topic rather well.  Many of the other citations are, of
course, related, and may be helpful in your search to uncover
precisely how Davis' formulas have been altered through time.  The
dissertation is available online at:
http://www.lib.kth.se/Fulltext/lukaszewicz010608.pdf   

Hope this is of use!  Please let me know if you have any further
questions that I can help with!