At Grade – Rail tracks are laid at the same level, or grade, as the surrounding landscape and intersecting roads or other transportation right-of-ways. An “at-grade alignment” means there is no separation between types of traffic – train, vehicle, pedestrian, or other. This is typical of railroad crossings in many towns and cities in which cars, bicycles and pedestrians must stop and wait while trains travel by.
Cut/Fill – A process in which a “cut” is made in the ground so that train rails can be laid lower than the surrounding terrain, and the earth removed from the cut – the “fill” – is used to build embankments along the cut that are higher than the surrounding terrain.
Aerial – Rail tracks are laid on a structure that elevates them above the landscape, allowing for other roads and railroad tracks to pass below the aerial structure.
Trench – Rail tracks are laid in an open ditch in the ground that allows the train to run below street level.
Tunnel – Rail tracks are laid in an enclosed structure running under ground level.
Embankment – Mounded earth used as a support along rail tracks that are built above ground level.
Retained – Concrete walls separating the rail tracks from buildings, roads and other transportation right-of-ways, and containing the earth retained from the cut/fill process or trenching.
Under Consideration – The rail alignment and preferred method for track construction is still being assessed.
*Map based on 2005 Statewide Programmatic EIR/S preferred route, and staff recommendation to Authority Board December 19, 2007 Mapping Sources: US Census 2000; CA Dept. of Conservation, Farmland Mapping and Monitoring Program 2000; California Resources Agency Legacy Project 2002; CA Dept. of Fish and Game 1999.