Highway Projects

Highway Program Glossary

Abutment:

A retaining wall that provides structural support for the deck of a bridge or overcrossing.

Auxiliary Lane:

A freeway lane dedicated to traffic entering and/or exiting the freeway, reducing interference with through traffic.

Backfill:

Earth or other materials placed between a bridge abutment and existing ground.

Bott’s Dots:

Reflectors that are affixed on freeway striping between traffic lanes to alert motorists when they drive out of their lane.

Braided Ramp:

A ramp that is grade-separated (physically separated, often on different levels) from an adjacent freeway ramp, thereby eliminating a conflict between traffic movements.

Caltrans:

The California Department of Transportation (Caltrans) is the state agency responsible for the safe operation and maintenance of the California highway system.

Carpooling:

An arrangement in which commuters share driving and the costs of an automobile for commuting. A carpool is formed with a minimum of two people.

Clear and Grub:

The use of bulldozers, payloaders, backhoes, tractor scrapers and dump trucks to prepare a corridor in advance of construction activities.

Clover-leaf Ramp:

A system of on- and off-ramps for a freeway that resembles a four-leaf clover or one or more petals of a clover.

CODE:

Community Enhanced Design Enhancements. A VTA program created to ensure 1996 Measure B Transportation Improvement Projects integrate the highest quality design enhancements which reflect the identity of the communities and neighborhoods in which they are located.

Congestion:

As defined by Caltrans, reduced speeds of less than 35 miles per hour for longer than 15 minutes.

Connector Ramps:

A roadway or ramp connecting two freeways, also called "branch connector" or "direct connector."

Crack and Seat Operations:

This process is performed in advance of repaving and involves cracking the pavement and letting the broken concrete settle. This allows water to more easily drain and extends the life of a newly paved roadway.

Dedicated Lane:

A lane of traffic designated for use by a specific type of vehicle, such as buses or a high occupancy (carpool) vehicle.

Falsework:

The temporary frame that supports the weight of a bridge or other structures during construction.

Flyover:

A direct connector that is an elevated structure moving traffic from one freeway to another.

Grade Separation:

Crossings at different levels by which intersecting roadways, railroad tracks, pedestrian walkways, bike paths or other structures avoid conflicting traffic operations.

High Occupancy Vehicle (HOV):

A vehicle with at least two riders, such as a bus, a taxi, a carpool or a vanpool. Also see: carpooling.

HOV (High Occupancy Vehicle) Lane:

A lane on a street or highway reserved primarily for the use of high occupancy vehicles, either all day or during specified periods, for example, during rush hours.

HOV Direct Connector Ramp:

A structure providing uninterrupted access between freeways that enables HOV vehicles to move directly from the HOV lane of one freeway to the HOV lane of the second freeway, without leaving the commuter lane to exit one freeway only to merge back across the next freeway into its HOV lane.

Interchange:

Where two highways meet and intersect.

Lane Closure:

A lane of traffic on a roadway closed to vehicles, generally to accommodate construction activities.

Lane Numbering:

Freeway lanes are numbered from the median, or center area between opposing traffic, to the outside shoulder, or right side. Hence, what is sometimes called "the fast lane" is the number one lane.

Lane Reduction:

A closing of one or more lanes, but not all lanes, to safely accommodate construction activities.

Lane Shift:

Restriping of a roadway to move lanes of traffic to either the left or right of their current position. Temporary lane shifts are often used during construction while work is underway in either the roadway’s median or the outside shoulder.

Mechanically Stabilized Earth Walls:

A segmented, precast retaining wall that supports earthfill embankments. MSEWs utilize horizontal metal straps buried in the fill as anchor points.

Median:

The portion of a divided highway separating traffic traveling in opposite directions.

Mitigation:

Actions or design features that reduce a project’s impact on environmental resources. Mitigation actions will avoid, minimize and/or compensate for adverse effects on the environment.

Mixed-flow:

A lane of traffic that carries both HOV vehicles and single occupancy vehicles.

Pile Driving:

Usually 40 to 80 feet in length, concrete shafts called piles are driven into the ground until striking solid material, serving to anchor the structure built on top of them.

Ramp Meters:

A traffic signal used at freeway on-ramps to control the rate of vehicles entering the freeway.

Retaining Wall:

A wall built to keep a bank of earth in place.

Soundwall:

A solid masonry wall built between the freeway and adjacent businesses or residences designed to reduce noise impacts.

Utility Potholing:

The process of locating existing sewer, water, electric and other conduits by digging a small but deep hole in the area where the pipe is shown on the plans.

Weaving Operations:

Refers to the competing movements of cars trying to enter and exit the freeway on the same stretch of roadway.