California Department of Transportation

Welcome to the Highway 1 Project Finder!!

Photo of Cone Peak and Highway 1 CHMP Logo

Glossary of Terms

AC Overlay. A mixture of asphalt and concrete (AC) spread over the surface of the road.

California Environmental Quality Act. (CEQA) was enacted in 1970 in order to ensure that state and local agencies consider the environmental impact of their decisions when approving a public or private project. 

CHMP. Coast Highway Management Plan.

Crib Wall. A type of retaining wall made from stacked concrete members that form vertical box columns and are filled with solid earth materials.

Culvert. A culvert is closed conduit, such as a metal pipe, which allows water to pass under a highway, minimizing erosion.

Erosion. Erosion is the wearing away of a surface by some external force, such as water, wind, and/or temporal changes. In addition, along the Big Sur Coast Highway, wave erosion has a large influence on the geologic features of the coastline.

Masonry Wall. A type of retaining wall made of rock or stone, often utilizing locally-available material.

Postmile. Postmiles are used as units of measurement and as a method of location out in the field. Listed in miles, postmile values increase from south to north or west to east depending upon the general direction the highway follows within the state. Postmile values increase from the beginning of a route within a county to the next county line. Postmile values start over again at each county line.

Retaining Wall. Large earth retaining systems that stabilize slopes and are often used as alternatives to an embankment fill slope. Retaining walls minimize potential environmental impacts and reduce right of way takings by limiting the size of a project’s footprint. There are several types of retaining walls including crib walls and masonry walls.

Rock Scaling. The physical removal of loose rock from slope faces.

Runoff. The portion of precipitation that appears as flow in streams. Drainage or flood discharge which leaves an area as surface flow or a pipeline flow, having reached a channel or pipeline by either surface or subsurface routes.

Seismic Retrofit. Earthquakes are naturally occurring events that have a high potential to cause damage and destruction. While it is not possible to completely assure earthquake proof facilities, every attempt should be made to limit potential damage and prevent collapse. Seismic retrofits are upgrades to existing structures which increase strength and durability and make the structures more earthquake resistant.

Sidehill viaduct. A bridge-like structure spanning an unstable area. One side of the bridge is supported by the ground, and the other side is supported by columns or piers.

Slide. Gravitational movement of an unstable mass of earth from its natural position.

Slipout. Gravitational movement of an unstable mass of earth from its constructed position. Applied to embankments and other man-made earthworks.

Tieback Wall. A retaining wall whose face consists of vertical piles connected by timber or concrete horizontal members. Anchors drilled into the earth behind the wall add additional stability.

Last updated: July 31, 2007