Glossary of Terms

Capacity
The maximum number of vehicles that a given section of roadway or traffic lane can accommodate in one direction in one hour.

Collector-distributor lane

A parallel roadway designed to remove weaving from the main line and to reduce the number of mainline entrances and exits.

Columbia River Datum (CRD)

The plane of reference from which river stage is measured on the Columbia River from the lower Columbia River up to Bonneville Dam, and on the Willamette River up to Willamette Falls. Equals 1.82 feet above Mean Sea Level (equivalent to NGVD) at Vancouver, Washington.

Congestion

A condition that occurs when the demand is greater than the transportation system’s capacity. Recurrent congestion is caused by constant excess volume compared to capacity. Nonrecurring congestion is caused by actions such as special events and/or traffic incidents. For highways, congestion is traffic moving at or slower than 30 miles-per-hour.

Construction staging area

A temporary area where vehicles, supplies and construction equipment are positioned for access to and use at a construction site.

Context Sensitive Solutions
A collaborative, interdisciplinary approach that involves all stakeholders to develop a transportation facility that fits its physical setting and preserves scenic, aesthetic, historic and environmental resources, while maintaining safety and mobility.

Corridor

Highway lanes associated right of way and the adjacent area that is visible from and extending along the highway. The distance the corridor extends from the highway could vary with different basic qualities.

Cost Estimate Validation Process (CEVP)

The project’s cost-risk estimating process that reviews and validates cost and schedule variables such as inflation, cost for materials or labor and the availability of funding in order to actively manage and avoid cost overruns. 

Couplet

A fixed method of routing two directions of travel on two adjacent, parallel streets, instead of placing both directions of travel on a single street.

Cut-through traffic

Traffic not originating in, or destined to, the immediate neighborhood.