The Folsom late night service on SacRT Gold Line is funding in part, or completely, from a settlement between ECOS and Caltrans, from a lawsuit over expansion (induced demand) of Hwy 50. The exact amount and period of time is not known, though we have asked for more information.
See two posts from ECOS:
https://www.ecosacramento.net/2018/05/letter-from-ecos-to-caltrans-re-hov-lane-settlement/
https://www.ecosacramento.net/2018/06/evening-hours-on-light-rail-gold-line-extended/
Sacramento Transit Advocates and Riders (STAR) 