This line shapefile represents commuter rail routes in California as of 2013. Commuter rail systems typically provide passenger service within a single region and occasionally, between regions. Service is more frequent during peak commuting periods. This layer includes the routes of commuter rail services in California's four key markets: 1) Caltrain offers service from San Francisco through the San Francisco Peninsula to San Jose and Gilroy. 2) The Altamont Corridor Express (ACE) offers service from Stockton to San Jose via Livermore and Fremont. 3) Metrolink offers a large network of commuter rail services between Los Angeles, Orange, Riverside, San Bernardino, San Diego, and Ventura counties. 4) COASTER commuter trains offer service along the San Diego County coastline, from Oceanside to San Diego via Carlsbad, Encinitas, and Solana Beach. All rail alignments segmented by milepost as listed in the California Regional Timetable 20. This layer is part of a collection of GIS data created by the California Department of Transportation (Caltrans).This dataset is intended for researchers, students, and policy makers for reference and mapping purposes, and may be used for basic applications such as viewing, querying, and map output production, or to provide a basemap to support graphical overlays and analysis with other spatial data.