This line shapefile represents traffic bottlenecks, or heavy congestion during peak a.m. and p.m. travel periods, on California's State Highway system during 2010. These data were derived from the California Department of Transportation (Caltrans) HQ Traffic Operations Asset Management Branch and prepared by Caltrans as part of the Mobility Performance Report (MPR). The MPR is prepared by Caltrans and district staff providing detailed data about highway system performance related to congestion and mobility. Caltrans collects vehicle counts and calculates speeds at all hours of the days and the week of major metropolitan areas throughout California via the Caltrans Performance Measurement System. This information helps identify congestion bottlenecks and results in more cost-effective investments to improve performance of the State Highway System. 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.