Hi,
The agreement was due to BOTH the AT&SF taking Raton and the D&RGW being leased to the AT&SF (hanging bridge is an AT&SF construction). I think the third party was the CB&Q.
AT&SF was not allowed to build west of the front range and the D&RG was not allowed to build south for 10 years. I think the CB&Q was also not allowed to build into the mountains for 10 years.
When Palmer lost the D&RG, he retained control of the RGW/D&RGW in Utah. The branch south into south central Utah was to be a sothern extension. Plans to build west from Green River to the Salinas(?) branch for the southern mainline to Mexico City had been located.
Would have been interesting trying to cross the canyons along the Colorado River.
Doug vV