Bernie, you can read about the Composite Speed Rating (CSR), new to RDSS2 (i.e. not in older Sartin programs) in the RDSS Documentation PDF found in the
RDSS Documentation section.
Here is the link to the RDSS Documentation PDF, which you can download and read for handy reference:
http://www.rdss2.com/pubs/RDSS2.1.Glossary.pdf
CSR is first mentioned on Page 3 of the Documentation. In the PDF, you can search for Composite Speed Rating or CSR to find other references to this factor.
You can also search the P&C site using the Site Search tool (
http://www.sartinmethodology.com/googlesearch) to find existing discussions about CSR and its usage.
Still, I can recommend you talk to Dick M (rmath) about the work he has done with this and other factors. He has done that a lot in other discussion threads.
Ted