CELE TERMS (all subjects)

Runway

A defined surface on an airport prepared or suitable for the landing or takeoff of airplanes.

Jerk

The rate of change in acceleration (or less often, deceleration).

Time Headway

Time elapsed between the front bumper of one vehicle and the front bumper of the following vehicle passing a given point.

Delineators

Roadside markers used to guide drivers through turns, especially at night or at times of poor visibility.

Design Speed

The maximum speed at which vehicles can continuously travel safely under favorable conditions.

Ballast

Gravel used as the base below the track for rail.

Base Course

The layer of the pavement immediately below the binder course or wearing course.

Waste

The materials excavated and thrown away which is no longer necessary to form an embankment.

Asphalt

A dark brown to black cementitious material solid or semi-solid in consistency, in which the predominating constituent is bitumen which occurs in nature as residue in refining petroleum.

Sounding

The determination of water depth at a certain fixed point.

Stream Gaging

The art of making measurements of the flow of water in open channels.

Stream

A current or steady flow of water running along the earth's surface.

Stadia

A plural name of a Greek word originally applied in measuring distances for athletic contests.

Stadia Constant

The distance from the center of the instrument to the principal focus.

Secular Variation

An extremely slow swing of the magnetic needle, periodic in nature, extending over a very long period of time due to the shifting of the earth's magnetic interior.

Parallax

Difference in direction of a heavenly body as seen from the surface and from the center of the earth.

Limit of Economical Haul

The distance within which it is more economical to haul materials than to throw them as waste.

Dredging

The process of widening, enlarging, clearing, or deepening of channels in harbors, rivers, and canals.

Hydrographic Survey

Refers to surveying streams, lakes, reservoirs, harbors, oceans, and other bodies of water.

Peak Hour Volume

The maximum number of vehicles that pass a point on a highway during a period of 60 consecutive minutes.

Annual Average Daily Traffic

The average of 24-hour traffic counts collected every day in the year.

Vehicle Miles of Travel

A measure of travel usage along a section of road, calculated as the product of the volume and the length of roadway.

Passing Sight Distance

Minimum sight distance required on a two-lane, two-way highway that will permit a driver to complete a passing maneuver safely.

Volition Time

The time taken for final action.

Density

The number of vehicles per unit distance occupying a section of roadway at a given instant time.

Traffic Volume

The number of vehicles moving in a specified direction on a given lane or roadway that pass a given point during specified unit time.

Traffic Capacity

The maximum number of vehicles that can pass a given point on a roadway in a specified time period under prevailing conditions.

Traffic Density

The number of vehicles occupying a given length of roadway at a specific time.

Jam Density

The density of vehicles on a roadway at which traffic flow comes to a complete stop.

Wakes

Waves formed by moving ships or boats.

Seismic Wave

Waves formed by earthquake disturbances.

Tides

Waves formed by gravitational attraction between the moon and the sun.

Wind Wave

Waves under the influence of the winds that generated them.

Diffraction

The spread of energy along a wave crest.

Refraction

The bending of waves as they slow down when entering shallower water.

Swell

Waves that have propagated beyond the initial winds that generated them.

Duration

The time that the wind blows across the water.

Spring Tides

The highest tide occurring at intervals of half a lunar month when the sun, moon, and earth align.

Neap Tides

The lowest tide of the month occurring when the moon is in its quarter phase.

Diurnal Tide

Tides that occur twice during a lunar day.

Wind

The circulation of masses of air parallel to the earth's surface.

Wind Rose

A graphical representation of the direction, frequency, and intensity of winds at a particular location over time.

Beaufort's Scale

A scale used to measure the intensity and speed of winds.

Higher High Water

The higher of the two high waters of any diurnal tide.

Mean Range

The height of the mean high water above mean low water.

Mean Sea Level

The mean height of mean high water above mean low water.

Flood Current

The tidal current setting into bays and estuaries along the coast.

Tide

The regular periodic rise and fall of the surface of the seas.

Seiche

The flow of seawater in the horizontal direction that accompanies tidal variation of sea level.

Fetch

The straight line stretch of open water available for wave growth without interruption of land.

Breakwater

A structure that protects the harbor from stormy waves.

Jetty

A solid structure projecting into the sea perpendicular to the shore to berth vessels.

Wharf

A platform built parallel to the shore within the harbor to berth vessels.

Quay

A platform built in the harbor parallel to the shore and backed up by ground.

Pier

A berth structure projecting out from the shoreline.

Port

A sheltered place where a ship may receive or discharge cargo.

Groin

A shore protection structure built perpendicular to the coastline to retard littoral transport of sediment.

Aquifers

Deep groundwater deposits where underground water is available for supply and irrigation.

Laminar Flow

A fluid flow where the fluid travels parallel to adjacent layers without crossing paths.

Turbulent Flow

A condition of flow characterized by irregular paths of fluid particles.

Bernoulli Principle

A principle stating that the increase in kinetic energy per unit weight is equal to the decrease in potential energy per unit weight.

Torricelli Law

The theoretical velocity of a jet of liquid issuing from an orifice under a head of h.

Velocity Head

The difference between the hydraulic grade line and energy grade line.

Critical Flow

A type of open channel flow where the Froude Number is equal to 1.

Open Channel Flow

A conduit in which liquid flows with a free surface subjected to atmospheric pressure.

Weir

An overflow structure built across an open channel for measuring or controlling flow.

Hydrometer Analysis

A test used to determine the grain size distribution of soils passing the No. 200 sieve.

Hazen's Effective Size

The grain size corresponding to 10 percent passing on a grain-size distribution curve.

Relative Density

The ratio of the difference between the void ratios of a cohesionless soil in its loosest and existing natural state.

Soil Consistency

Describes the degree and kind of cohesion and adhesion between soil particles.

Rupture Resistance

A field measure of the ability of soil to withstand applied stress or pressure.

Cohesion

The attraction of one water molecule to another due to hydrogen bonding.

Adhesion

The attraction of a water molecule to a non-water molecule.

Stickiness

The capacity of soil to adhere to other objects, estimated at moisture content that displays maximum adherence.

Plasticity

The degree to which a soil can be molded or reworked without rupturing.

Liquid Limit

The moisture content at which soil changes from a plastic to a liquid state.

Plastic Limit

The moisture content at which soil begins to behave as a plastic material, crumbling when rolled into a thread of 3.18 mm in diameter.

Shrinkage Limit

The moisture content at which no further volume change occurs with further reduction in moisture content.

Compaction

The densification of soil by removal of air, which requires mechanical energy.

Optimum Moisture Content

The moisture content at which the maximum dry unit weight of soil is attained.

Vibroflotation

A technique for in situ densification of thick layers of loose granular soil deposits.

Flow Line

A line along which water particles travel from upstream to downstream in a permeable soil medium.

Equipotential Line

A line along which the potential head at all points is equal.

Flow Nets

Constructed to calculate groundwater flow in the media that combine flow lines and equipotential lines.

Effective Stress

The sum of the vertical components of the forces developed at the points of contact of the solid particles per unit cross-sectional area of the soil mass.

Immediate Settlement

Settlement caused by the elastic deformation of dry soil and of moist and saturated soils without any change in moisture content.

Primary Consolidation Settlement

The result of volume change in saturated cohesive soils due to the expulsion of water that occupies the void spaces.

Secondary Consolidation Settlement

The result of the plastic adjustment of soil fabrics after primary consolidation.

Shear Strength

The internal resistance per unit area of the soil mass to resist failure and sliding along any plane.

Overconsolidation Ratio (OCR)

The ratio of preconsolidation pressure to present effective overburden pressure.

Unrestrained Slope

An exposed ground surface that stands at an angle with the horizontal, which can be natural or constructed.

Subsurface Exploration

The process of identifying the layers of deposits that underlie a proposed structure and their physical characteristics.

Method of Slices

A method for analyzing the stability of a slope in two dimensions by dividing the sliding mass into slices and analyzing forces on each.

Base Failure

A type of failure where the surface of sliding passes at a distance below the toe of the slope.

Slope Failure

A type of failure where the surface of sliding intersects the slope or is above its toe.

Toe Circle

The failure circle in slope failure that passes through the toe of the slope.

Plastic Equilibrium

The condition in which every point in a soil mass is on the verge of failure.

Lateral Earth Pressure

The pressure that soil exerts against a structure in a sideways, mainly horizontal direction.

Active State

The state when a soil mass is allowed to relax or move outward to the point of reaching the limiting strength of the soil.

Spread Footing

An enlargement of a load-bearing wall or column that spreads the load of the structure over a larger area of soil.