Valley Rail is a project to expand Altamont Corridor Express (ACE) and Amtrak California San Joaquins commuter rail services, divided into several segments which include two service extensions from Stockton to Sacramento and Merced, station improvements, and grade separation of the Stockton Diamond.
The ACEforward project was initiated in 2013 to expand ridership by improving service reliability and frequency on the existing route between Stockton and San Jose, and by extending the route east from Stockton to Merced; during its development, financial and logistical challenges were identified which precluded operating more trains on the existing segment, and the Valley Rail project replaced ACEforward in 2017, initially focusing on the eastern extension to Merced. The first environmental impact reports for Valley Rail were released in 2018; funding was secured in 2023, and construction began in 2024.