absorption – The act of liquid entering permeable pores in a solid body.

 

abstraction – The process of pumping or removing groundwater.

 

abutment – The outermost ends on a bridge that support loads, including carrying the weight of the deck, and also preventing the bank from sliding under.

 

accelerator – A chemical admixture used in concrete mixes that increases the rate of hydration, and thus reduces the concrete’s setting time and increases the early age strength.

​

accelerogram – A graphical representation of the acceleration of the ground during an earthquake that is obtained from a seismograph.

 

accelerograph – An instrument in a self-contained box that measures and records the acceleration of the ground during an earthquake.

​

acre – A unit of land area that is equal to 43,560 square feet or 10 square chains.

​

activator – A substance that assists in carrying out anaerobic digestion in a septic tank.

​

active earth pressure – A condition where the soil mass moves horizontally outward to the point of reaching the limiting strength of the soil.

​

active zone – The area behind a retaining wall that lies above the failure plane.

​

activity – The third level within the construction hierarchy that is a physical segment of a project, and that utilizes resources. The various activities of a project are outlined in the Critical Path Method schedule.

​

addendum – Supplementary information that is issued by the owner to potential contractors either modifying or clarifying the bid documents, and ultimately becoming part of the contract documents.

​

admixtures – Materials that are added to concrete to alter its characteristics.

​

adsorption – The attraction and/or adhesion of small particles to a surface.

​

aerobic – Requiring oxygen for growth.

​

aftershocks – Smaller earthquakes that occur immediately after a large earthquake, and can continue over a period of weeks, months, or years.

​

Agency Construction Management – A project management method in which a contract is formed between the owner and construction manager agency, allowing the agency to act as the owner’s representative during the construction phase of a given project.

​

aggregate – A material (i.e. sand, slag, crushed stone, or gravel) composed of loosely compacted particles typically used in construction applications.

​

agreement – See contract.

​

air entrainment – Air bubbles that have been intentionally incorporated into a concrete mix to increase its strength and durability.

​

alignment – The route of the road.

​

alkalinity – The measure of the quantitative capacity of water to neutralize an acid.

​

alley – A narrow lane that provides access to the rear of private or public properties.

​

alligator cracks – An interconnected network of cracks that are formed within an asphalt pavement due to fatigue, weak underlying layers, or excessive loading conditions.

​

allowable bearing capacity – Ultimate bearing capacity divided by a factor of safety.

​

alluvial aquifer – A water-bearing layer of sediment that has been deposited in river channels, and typically lies above fractured rock aquifers. Water levels within this type of aquifer generally fluctuate over time.

​

alluvium – Loose, unconsolidated sediment that has been deposited by water.

​

ambient temperature – Temperature of air that surrounds an object.

​

Americans with Disabilities Act (ADA) – A law that was enacted to prohibit discrimination based on disability.

​

amplitude – A measurement of the magnitude or total distance traveled by an oscillation of a vibration. Peak-to-peak amplitude implies the change between the peak (highest value) and the trough (lowest value).

​

anaerobic – The act of living or growing without the presence of oxygen.

​

angle iron – An L shaped steel support.

​

angle of repose – The steepest angle relative to the horizontal plane at which granular material can be piled without slumping.

​

angular frequency – Expresses the rate of rotation in units of degrees per second. Angular frequency is equivalent to 2π multiplied by the frequency, which is in hertz.

​

annealing – The process of increasing a material’s ductility by heating it and afterwards letting it cool. This will in turn decrease the material’s brittleness.

​

anticline – A fold within a geologic formation in which the beds bend downward in the opposite direction from the crest.

​

apparent low bidder – A qualified contractor who has submitted the lowest bid to the owner, based on the bid documents and all related addendum reflecting the proposed construction project.

​

apparent specific gravity – The ratio of the weight in air of a unit volume of oven-dried aggregate to the weight in air of an equal volume of distilled water at the stated temperature.

​

application for payment – A written and official request from the contractor to the owner seeking payment, based on the summary of work that has been completed up to a particular date.

​

aqueduct – A bridge or a man-made canal that is used to convey water from one point to another.

​

aquiclude – A relatively impervious layer that can exist either above or below an aquifer, and that will not readily transmit groundwater quickly enough to supply water to a well.

​

aquifer – A layer of soil or permeable rock that allows the extraction of groundwater using a well.

​

aquitard – A layer that restricts water flow from one aquifer to another.

​

arbitration – A technique that is used to settle claims between parties by allowing a panel of specialists to hear the evidence and render a decision.

​

area of influence – The widest part of the cone of depression that is created within the ground, when dewatering operations occur using a pumping well in an unconfined aquifer.

​

arching – Stress distribution that allows the load to transfer from a softer to a stiffer region of a structure. Arching is also known as a “bin effect.”

​

architect – A person who is licensed to plan, design, and oversee the construction of buildings or other structures.

​

architect-engineer – An individual or a firm that provides services such as planning, architecture, estimating, engineering, or any other technical service pertaining to planning, designing, and construction.

​

arrival – The appearance of a given seismic phase on a seismogram.

​

arterial road – A high capacity urban road that is characterized by continuity of movement.

​

artesian aquifer – A confined aquifer that contains groundwater, which is under positive pressure. If a well were to be drilled through an artesian aquifer, the water could potentially rise above the ground surface.

​

artesian well – A well in which water flows out naturally without the need to pump any water.

 

artificial recharge – The process of intentionally injecting water into an aquifer.

 

asbestos – A mineral fiber that is found in soil and rock and is known for its heat resistance.

 

as-built drawings – Contract drawings that are updated during the construction phase of a project reflecting any changes due to request for information (RFI) documents or other change orders, and ultimately becoming

the final set of drawings after construction is complete.

​

aseismic – Referring to a region or a fault on which no earthquakes have been observed.

​

asperity – An area on a fault that is stuck and does not move.

​

asphalt – A black viscous liquid of petroleum typically used in pavement applications.

​

asphalt concrete – A composite material used in pavement construction that is formed by mixing aggregate with asphalt.

​

at rest earth pressure – The in situ lateral pressure (i.e. the natural state of a soil mass).

​

atmospheric pressure – The force per unit area that is exerted by the atmosphere.

​

Atomic Energy Act – A law that manages nuclear technology.

​

Atterberg limits – Significant water contents that a fine-grained soil can reach, such as the plastic limit, the liquid limit, and the shrinkage limit.

 

auger-cast pile – A deep foundation element that is constructed using a drill rig. After advancing the hollow stem auger to the specified depth, grout is simultaneously pumped through the auger as it is being removed. A

reinforcing steel cage can be placed within the borehole after the auger has been withdrawn and prior to the grout setting up.

​

auxiliary lane – The extra lane constructed between interchanges that serves to separate entering and exiting vehicles from through traffic, ultimately allowing drivers to merge into traffic.

​

auxiliary loads – Dynamic live loads such as impact loads, cranes, or monorails.

​

axial flow pump – A type of centrifugal pump that provides a high flow rate and a low head, since the flow leaves in the same direction as it enters.

​

axial force – A force that acts directly on an object’s center axis, and tends to either elongate or shorten the member.

​

axle load – The total weight that the wheels, connected to a given axle of a vehicle, transmit to the roadway.

​

backfill – Any type of soil or rock material that is placed within an excavation during earthwork operations.

 

backflow – An undesirable condition in which non-potable water flows into the drinkable water system as a result of a significant difference in pressure.

​

ballast – A material composed of crushed stone that is used to provide stability beneath railroad tracks or structures.

​

bank yard – A yard of material as it lies in its original position prior to excavation operations.

​

barge – A flat-bottomed, non-motorized water vessel that typically carries freight.

​

base course – A layer of granular material that is placed, graded, and compacted directly on top of either the exposed subgrade or a prepared subbase, to provide a stable base prior to paving operations.

​

basin – A man-made or natural topographic low area in which water can drain to, or that can be used to catch debris.

​

batter pile – A solid piece of material (i.e. timber, concrete, steel, etc.) that is typically driven into the ground at a specified angle to provide a higher lateral resistance to loads.

​

beam – A structural member supporting its own weight, in addition to applied loads, by primarily resisting bending.

​

beam-column – A member that is subject to both axial compression and bending. The loads will be carried both parallel and transverse to its longitudinal axis.

​

bearing capacity – The capacity of soil or rock to support loads that are applied to the ground.

​

bearing capacity factors – Factors used in the bearing capacity equation that have been derived empirically, and that correlate with the angle of internal friction.

​

bearing capacity failure – A scenario when the shear stresses exceed the shear strength of the soil.

​

bearing wall – A wall that supports loads in addition to its own weight. These walls are typically constructed of concrete or block.

​

bedding – Granular material that is placed at the base of an excavation to provide stability and alignment during the installation of pipe or conduit.

​

bedrock – A deposit of solid, consolidated rock that is typically found beneath soil or other unconsolidated material.

​

bell-and-spigot pipe joint – An unexpanded end that inserts into an enlarged diameter or bell, and then sealed.

​

bench – A flat step typically created within an embankment to either provide stability or allow backfilling of other material.

​

bench mark – A reference point marked by surveyors on a permanent object, that is used to indicate a verified elevation.

​

bending moment – The measure of the internal stresses across a cross-section of a member when an external force is applied, which in turn causes it to bend.

​

benefit cost ratio – The ratio of the benefits to the costs, which are expressed in discounted present values.

​

Benioff zone – A flat seismic zone where earthquakes occur as a result of the interaction between the oceanic crustal plate and the continental plate.

​

bentonite – A manufactured product that has a high concentration of montmorillonite and is typically used as a filler.

​

berm – A raised barrier between two areas that can provide erosion control or serve as a border.

​

Best Management Practices (BMP’s) – The act of reducing water pollution and flood risk by taking cost-effective and appropriate measures to address a particular problem.

​

bevel – An angle between two sides of a solid body other than a right angle.

​

bid – A price that is proposed and submitted by the general contractor to the owner, to perform the work in accordance with the contract documents.

​

bid bond – A pledge provided by a third party (i.e. a surety) guaranteeing the contractor will complete the project at the specified bid price and also submit payment and performance bonds.

​

bidder – An individual or a business that submits a proposal to perform a specified scope of work.

​

biochemical oxygen demand (BOD) – A measure of the amount of dissolved oxygen required for organisms to break down organic material in water, for a specified amount of time and at a specific temperature.

​

bitumen – See asphalt.

​

blasting – A ground improvement technique using multiple explosives within drilled boreholes that are detonated in an attempt to densify the surrounding soil.

​

blind thrust fault – A type of thrust fault that does not appear at the surface, since it can diffuse into a fold beneath the ground surface.

​

blow count value – See N-value.

​

body wave – A seismic wave that moves through the interior of the Earth. P and S waves are body waves.

​

bog – A type of wetland that accumulates a large amount of peat.

​

bond – A pledge provided by a third party (i.e. a surety) that protects the owner from the risk that can arise with construction.

​

bond beam – A horizontal structural element, filled with concrete and reinforcing steel, that is typically used in masonry construction to support roof loads.

​

boring – The process of drilling a hole into the earth, while performing field tests and/or collecting samples that will be used for laboratory testing.

​

borrow – Material that is excavated from a quarry or pit and afterwards transported to a project site to be used during earthwork operations.

​

bottom chord – The lowest longitudinal member of a truss.

​

Boussinesq equations – Published equations based on the theory of elasticity to determine the change in soil stress. The equations use a specific type of applied load, such as a point load, uniform load, or linearly increasing load.

​

box girder – A hollow steel beam that is rectangular in section.

​

braced excavation – A temporary trench or cut that has been braced with structural members to resist the lateral pressure of earth material.

​

brake reaction time – The time that has passed between recognizing that an obstacle is in the roadway and the application of the brakes.

​

bridge scour – The erosion of earth material from around bridge abutments or piers which can potentially lead to catastrophic failure of the structure.

​

bridging documents – Information, such as partial drawings, that is prepared by the designer and available to the constructor during the bidding process.

​

Brinell test – A method of determining the hardness of forgings or castings by using a steel ball to apply a constant load for a specific amount of time.

​

brittle – A characteristic of a material pertaining to the inability to stretch before failing. Brittle materials fail without warning.

​

brownfield site – An abandoned industrial or commercial facility that is available for reuse.

​

buckling – A sudden failure of a structural member due to a compressive stress.

​

buffer – A sensitive area that is designated by a local jurisdiction.

​

buffer strip – An area of close-growing vegetation that serves to protect a designated waterway or piece of land from erosion or other environmental problems.

​

bulk density – The weight of dry soil divided by the total volume of soil.

​

bulk head – A structure that is erected to serve as either a coastal defense against waves or as protection against erosion.

​

bulk unit weight – Total weight of the soil particles and water that are present in a unit volume of soil.

​

bulking – The expansion of soil or rock during excavation operations.

​

buoyancy – The power to support a floating body by exerting an upward force.

​

butt weld – A butt joint that is created by welding.

​

C factor – A coefficient that signifies the relative roughness of a pipe in the Hazen-Williams formula for water flow in a particular pipe.

​

caisson – A large-diameter, watertight retaining structure used for deep excavations. The term caisson has also been frequently interchanged with a drilled shaft foundation.

​

caliche – See hardpan.

​

California Bearing Ratio (CBR) test – A laboratory test performed for pavement applications that measures the strength of a subgrade. A higher CBR value indicates a stronger subgrade.

​

canal – A man-made open waterway that is constructed to primarily transport water or to connect two bodies of water.

​

cantilever – A structure that is supported only at one end and projects at the other end.

​

capillarity action – The ability of water to flow between particles without the assistance of gravity.

​

capillary head – The difference in elevation, expressed in units of water head, between the position of the meniscus at the given time of measurement to the ultimate position of the meniscus.

​

capillary migration – The movement of water through soil or rock due to the molecular attraction between the material and water.

​

carcinogen – An agent that has the ability of causing cancer.

​

cash flow – The flow of money into and out of a company or project.

​

casing – A hollow, steel cylinder that is inserted into the ground to prevent groundwater from infiltrating or soil from sloughing into the boring. Casings are typically used during drilled shaft construction or well installation.

​

casing head – A heavy weight welded to the first string of casing in oil and gas well drilling, allowing the suspension of intermediate strings of casing.

​

cast-in-place concrete – Ready-mix concrete that is placed into removable forms that have been erected on-site.

​

cast iron – A heavy ferrous alloy that is used for the construction of valves or fittings. This type of material was used in the past to convey water, gas, and sewage.

​

catch basin – A concrete inlet structure that allows water to enter into a drainage system.

​

cavitation – The formation of vapor bubbles in a liquid as a result of forces and/or local low pressures.

​

centrifugal pump – A pump used to transport fluids by rotating a high-speed impeller on a shaft within a casing.

​

centripetal force – The force that is required to keep an object moving with a uniform speed in a circular path.

​

centroid – The center of mass.

​

cesspool – See seepage pit.

​

chamfer – See bevel.

 

change order – A written agreement between the owner and contractor describing revisions to the original contract documents that can include addition or deletion of scope of work. Any necessary compensation due to the changes and the time impact to the schedule are also presented within the change order documents.

​

channel – An artificial or natural course for water to flow through.

​

chip seal – An inexpensive pavement maintenance technique that is primarily used as a short-term fix. An asphaltic emulsion, along with finely graded aggregate, is applied on top of the deteriorated pavement surface.

​

chord – An outside member (measured in a straight line connecting two points) of the truss.

​

circumference – The linear distance measured around the edge of a closed circular object.

​

cladding – The exterior covering of the structural members of a building, which provides protection against weather or that can serve as an aesthetic piece.

​

Clean Air Act – A law that regulates air emissions on a national level.

​

Clean Water Act – A law that regulates the discharge of pollutants into the nation’s surface waters.

​

cleanout – An opening at the bottom of a masonry wall that allows for inspection and removal of debris. A cleanout can also mean an opening or passage within a drainage system that provides access in order to clean obstructions.

​

clearing and grubbing – The process of removing existing vegetation that is found at the surface.

​

coagulation – The process of adding chemicals to destabilize charges on particles that are in water, causing them to clump together.

​

coarse-grained soil – Soil that is least affected by water content changes, such as sand or gravel.

​

coefficient of consolidation – A coefficient which measures one-dimensional consolidation (i.e. the soil does not experience any lateral strain). The coefficient can be obtained from a laboratory oedometer test.

​

coefficient of curvature – A measure of the shape parameter that can be determined from a grain size distribution curve.

​

coefficient of friction – The measure of resistance to sliding that a particular surface exerts on an object (i.e. at the interface of the two surfaces).

​

coefficient of lateral earth pressure – The ratio of the horizontal effective stress divided by the vertical effective stress.

​

cofferdam – A temporary watertight enclosure that allows dry work to be performed.

​

cohesion – A component of shear strength that allows the particles of fine-grained soils to bond.

​

cold patch – A mix of cold asphalt that is used to quickly and/or temporarily repair roads by placing it directly into a pothole, without depending on warm weather.

​

collapsible soil – Material that experiences a sudden reduction in volume and settles in response to wetting.

​

collateral loads – Miscellaneous loads in addition to the dead loads, such as mechanical or electrical components.

​

collector – A road that carries low to moderate volumes of traffic at low to moderate speeds.

​

colluvium – Loose, unconsolidated sediments that have been deposited at the base of slopes by gravity.

​

column – A vertical structural member that supports loads and transfers them to the foundation of a structure.

​

combined sewer – A sewer that serves not only as a sanitary sewer but also as a storm sewer.

​

combustible – The ability of materials to catch fire or to burn.

​

commissioning – The process of inspecting and testing the operational components of a project to ultimately provide certification.

​

community well – A well serving several houses or a neighborhood by providing domestic water supply.

​

commuter rail – A passenger train that can be operated by either diesel fuel or electricity and that operates within an existing rail corridor along freight rail lines.

​

compaction – The process of applying stress by mechanical means to soil or rock in an effort to densify the material.

​

compaction grouting – A ground improvement technique using a drill rig that injects an extremely low slump grout into the ground to densify the surrounding soil.

​

compaction test – A laboratory test used to determine the optimum moisture content at which a soil will achieve its maximum dry density.

​

compliance – The act of meeting the project specifications.

​

compounding period – The time interval between dates at which interest is paid and added to the amount of an investment.

​

compression – A force that presses a material together.

​

compressional waves – See P-waves.

​

compressive strength – The measurement of the maximum resistance that a concrete specimen can withstand when subject to an axial load, and typically expressed in pounds per square inch.

​

concentrated load – A load or force that is applied at a single point on a structure. Two important characteristics of a concentrated load are the magnitude of the force and the location of where the load is applied.

​

concrete – A mixture of sand, cement, gravel, and water that creates a hardened matrix of material.

​

concrete block – A rectangular brick usually containing hollow cores that is used in masonry construction. Concrete block is also known as a concrete masonry unit (CMU).

​

conductor – A material that permits the flow of electricity.

​

conduit – A pipe or a tube installed underground which carries electrical cables.

​

cone of depression – The groundwater elevations within the vicinity of a pumping well during dewatering operations.

​

Cone Penetration Test (CPT) – A method where a cone is pushed into the ground at a controlled rate to determine the soil stratigraphy. There are various types of cone penetration tests, such as electric, mechanical, mechanical-friction, and piezocone.

​

confined aquifer – A water-bearing stratum that is overlain and underlain by a confining layer that prevents water from seeping from the surface, and is typically under pressure.

​

connector – A road that carries low volumes of traffic at low speeds, typically distributing traffic to local streets.

​

consolidation – A process by which fine-grained soils decrease in volume by the expulsion of water.

​

consolidation test – A laboratory test used to determine the rate and magnitude of soil consolidation. The cohesive soil is loaded axially and restrained laterally during the test.

​

constructability review – A technique that reviews the proposed design to ensure that consistency is met and ease of construction is attained, in addition to evaluating cost.

​

construction company – The top level of the hierarchy in construction that is defined as an organization whose goal is to construct a project for an owner within a specified cost and time limit, while ensuring quality and safety.

​

construction documents – A set of contract drawings, project specifications, and addendum.

​

Construction Manager – An entity who works for the owner managing the entire project.

​

Construction Manager / General Contractor – A project delivery system allowing the owner to have separate contracts with the designer and constructor, while offering fast-track construction methodology. Also referred to as Construction Manager at-Risk.

​

construction operation – The fourth level of the hierarchy in construction that is defined as a technological segment of a project that can span several activities.

​

constructor – See general contractor.

​

consultant – An individual or a business hired by the designer to perform a portion of the scope of work.

​

contaminant – A hazardous substance that does not occur naturally.

​

contingency – A specific amount of money that an owner reserves throughout the duration of a project to account for any unforeseen conditions that may arise and require the constructor to be reimbursed.

​

continuous footing – A shallow footing that spans horizontally to support a wall over its entire length.

​

continuous weld – A weld that extends continuously from one end of the joint to the other.

​

contour line – A line that joins different points all having the same elevations.

​

contract – A document that outlines the relationship between two parties and specifically describes the rights and responsibilities of each party.

​

contract drawings – A set of paper or electronically produced graphic representations depicting all elements of work which form the project.

​

contracted weir – A rectangular barrier across a river that has a notch in order to alter the flow of water. A contracted weir has a crest length that is less than the width of the channel of approach.

​

contraction – The decrease in volume of loose soil as it is being sheared.

​

control joint – A formed groove in concrete that is created by either sawing or tooling, to allow cracking to occur in a controlled manner.

​

core – The central region of a dam or a skyscraper, or the innermost layer of the Earth.

​

core drilling – A drilling technique that uses a cylindrical drill bit to cut rock, soil, or concrete, ultimately allowing the core to be inspected.

​

corridor – A linear orientation of transportation routes, including highways and railroads.

​

corrosion – The deterioration of material due to chemical attacks.

​

corrosivity – The formation of rust due to corrosion.

​

corrugated metal pipe (CMP) – An economical material used to carry drainage water underground.

​

cost-plus contract – An agreement where the owner pays the general contractor or designer a specified fee to cover profit and overhead, in addition to project-related expenses.

​

course – The horizontal layer within a roadway section.

​

cover – The distance within a reinforced concrete member between the surface of the reinforcement and the outer surface of the member.

​

creep – Slow strain that can develop under sustained shear stress. Creep can also refer to slow movement along faults that does not produce any earthquakes.

​

crest curve – A type of vertical curve which connects an uphill road to a downhill road, and contains a high point or crest (opposite of a sag curve).

​

crib weir – A barrier constructed out of log cribs filled with rock.

​

cribbing – A temporary wooden structure used to support loads during construction.

 

critical activity – Any activity that is on the critical path and if not completed on time, will delay the entire project.

 

critical flow – The state of flow where the Froude number is equal to 1, and is thus the dividing condition between supercritical and subcritical flow.

 

critical height – The height of a slope that corresponds to a factor of safety of 1.0. Theoretically, if the factor of safety is above 1.0, the slope is stable.

 

critical path – A set of activities, having no float, that must be completed within the specified duration of a project, in order to prevent the contractor from incurring liquidated damages.

 

critical path method (CPM) – A scheduling technique that is used to plan a construction project. The project duration is analyzed by determining which set of activities have the least amount of scheduling flexibility.

 

crown – The uppermost portion of an embankment, pipe, or roadway section.

 

crust – The thinnest of the Earth’s three layers that is made up of various metamorphic, igneous, and sedimentary rocks. The crust is underlain by the mantle.

 

curing – The process of maintaining adequate temperature and humidity of freshly cast concrete to allow for proper hardening.

 

curtain wall – A wall that typically divides rooms, and which does not provide any significant structural support besides carrying its own weight.

 

cut-and-cover – A tunneling method that involves the excavation of a trench prior to constructing the tunnel, and afterwards filling around the structure with backfill material.

 

cylinder test – A laboratory test in which a sample of concrete is tested in compression to determine its compressive strength.

 

dam – A large barrier/structure constructed to hold water or underground streams. Earth dams can either be constructed using a systematic zoning of fill materials or simply using one soil type.

 

Darcy’s law – The expression that relates the flow rate to the hydraulic gradient, the permeability, and the cross-section area of flow.

 

datum – A reference level surface from which elevations are taken from.

 

dead load – A load that is constant over time, such as the roof or the structure itself.

 

dead storage – Storage below the lowest outlet levels of a given reservoir that will not be used.

​

deadman – A block which is buried to serve as an anchor for a retaining wall.

 

deck – A roadway that is supported on a bridge.

​

decontamination – The process of removing hazardous materials by chemical or mechanical means.

​

deep earthquake – An earthquake whose focus is located more than 300 km from the Earth’s surface.

​

deep foundation – The lowest part of a structure that transfers the load through weak layers to stronger layers below.

​

deflation – The decrease in the relative price of a good or service.

​

deflection – The displacement of a structural member due to a given load.

​

deformation – Change in shape of an object due to external forces or loads.

​

deformed bar – A steel reinforcing bar which is given ridges to provide better anchoring to reinforced concrete.

​

degree of saturation – The ratio of the volume of water divided by the total volume of voids, and expressed as a percentage.

​

delay – The difference between the actual travel time on a given segment and some ideal travel time of the same segment.

​

density – Mass per unit of volume. Density can also mean the number of vehicles that occupy a road lane per unit length at a particular instant.

​

depletion – The exhaustion of the supply of natural resources.

​

depreciation – The gradual decline in value of a capitalized asset.

​

desiccation – The process where fine-grained soil shrinks and dries.

​

design-build – A project delivery system that allows the owner to have a single contract with the constructor (i.e. design-builder), while offering fast-track construction methodology.

​

design speed – A chosen speed used during geometric designs of roadways. The design speed will allow drivers to safely and comfortably navigate the roadway.

​

designer – A professional engineer or licensed architect who performs the design and prepares specifications for the project.

​

detail – A drawing at a larger scale that depicts the materials to be used, in addition to the composition and dimensions.

​

detention basin – An excavated depression that temporarily stores stormwater to protect against excessive rainfall, and eventually drains out.

​

detention pond – A detention basin that maintains a permanent, aesthetic water surface.

​

detour – A temporary route that is provided for traffic due to a portion of the existing road being closed.

​

detritus – Material that has been broken down from rock due to either erosion or by mechanical means.

​

deviator stress – The difference between the major and minor principal stresses in a triaxial laboratory test.

​

dewatering – The procedure of removing or draining water from an active construction site by pumping techniques or simply evaporation. This procedure is typically performed to lower the groundwater table prior to excavation activities.

​

diaphragm wall – A wall that is constructed underground to provide either a temporary earth support or a permanent foundation system. The construction sequence involves excavating a trench, and placing reinforcing steel and pumping slurry into the exposed trench.

​

differential settlement – The difference in settlement between two points on a single foundation. If one part of a foundation settles more than the other part, this may lead to structural damage.

​

diffusion well – A well that is intended to convey surface water into an aquifer which will ultimately increase the groundwater supply.

​

dike – See levee.

​

dilation – The increase in volume of dense soil as it is being sheared.

​

dip angle – The measurement between the horizontal surface and the planar structure (i.e. fault or bed). This term is commonly used in rock mechanics when specifying the orientation of a fracture.

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direct costs – Expenses directly tied to a certain product or service, and can include human labor or machines, and materials pertaining to a process or system.

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direct runoff – The sum of the surface waters and the water flow in the top soil layer that ultimately reaches streams, rivers, or lakes.

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direct shear test – A laboratory test that measures the shear strength (i.e. cohesion and angle of internal friction) of soil or rock by plotting a stress-strain curve for each confining stress.

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distributed load – A load that is spread out over a large area on a structure. Distributed loads can be uniform or non-uniform.

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distribution box – A container that divides the flow of effluent from a septic tank into several seepage pits.

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disturbed wetland – An area, saturated with water, that has been impacted and therefore altered from a natural condition.

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ditch – See swale.

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dobie blocks – Small precast concrete blocks that are used to hold wire mesh and/or reinforcing steel to provide the appropriate cover.

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dolomite – A sedimentary carbonate rock similar to limestone but slightly harder. Dolomite is also known as dolostone, and it can be dissolved by acidic water, ultimately contributing to karst topography.

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domestic well – A well constructed to provide drinking water.

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doweling – The process of using pins of metal or wood to fasten two pieces of timber or concrete together.

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downdrag – A force that is induced on a deep foundation due to the downward movement of soil. If liquefaction-induced downdrag occurs, significant foundation settlement can occur.

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drainage basin – See watershed.

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drawdown – The lowering of the water level in an unconfined aquifer.

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dredging – The process of excavating earth material that is under water.

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drift – Slow or gradual lateral movement of a structure.

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drilled shaft – A deep foundation element that is constructed using a drill rig. The construction sequence involves advancing an auger to a desired depth, and after removal, the placement of a reinforcing steel cage within the exposed hole. Concrete is then tremied into the shaft. A casing can be used to control groundwater, and a bell can be constructed at the bottom to provide additional load bearing capacity and/or mitigate expansive soils.

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dry unit weight – The ratio of the weight of dry soil per unit volume.

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ductile iron (DI) – A type of material used to construct water pipes. Ductile iron pipe superseded cast iron pipes due to its superior physical characteristics.

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ductility – The ability of metal to deform under stress.

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dynamic compaction – A ground improvement technique which is performed by repeatedly dropping a heavy weight on the ground surface to improve the bearing capacity of loose, coarse-grained soils. A grid pattern is typically used during the operation.

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dynamic load – A load that is variable, such as wind or a vehicle that is in motion.

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early finish date – The earliest point in time that an uncompleted portion of an activity can finish.

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early start date – The earliest point in time that an uncompleted portion of an activity can start.

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earthquake – The sudden release of energy in the Earth’s crust as a result of the movement of tectonic plates. Earthquakes occur on faults, which may or may not extend up to the Earth’s surface.

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easement – The right to enter and/or use property for various purposes without actually possessing it.

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eccentric load – A load that is applied on a structure at a point other than the centroid of the section (i.e. away from the center).

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economic life – The time period that an owner expects to maximize net return or minimize the cost of particular goods or services.

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eductor – A water jet pump that is used to pump water through a nozzle and a venturi arrangement.

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effective interest rate – The interest rate of a given loan, which takes compounding into account.

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effective rainfall – Rain that produces surface runoff.

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effective stress – The pressure that exists between soil particles, keeping the grains interlocked. Effective stress is calculated by subtracting the pore pressure from the total stress.

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effluent – Wastewater that flows out of a treatment plant and is discharged into surface waters.

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egress – The act of leaving or exiting.

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ejector well – A well that is constructed to lower the groundwater table by using eductors.

 

elastic – The tendency of a material to return to its original shape after being deformed.

 

elastic limit – The maximum stress that can be applied to an elastic solid without causing permanent deformation.

 

electroosmosis – Movement of a fluid with respect to a soil mass as a result of an applied electric potential gradient. This method of pore water pressure control is typically used with low permeability soils.

 

empirical formula – A formula that is based on many observations and tests, but with no theoretical calculation.

 

emulsion – The suspension of small particles of one substance in another substance which the first will not mix with.

 

Endangered Species Act – A law protecting animals and plants from extinction as a result of nationwide economic growth.

 

end-bearing pile – A solid piece of material (i.e. timber, concrete, steel, etc.) that is mechanically driven into the ground, and which derives its load bearing capacity from the pile tip bearing on competent material.

 

energy dissipation – The conversion of mechanical energy into heat.

 

energy line – A line that represents the total head available to the fluid.

 

Energy Policy Act – A law created to address energy production by establishing management goals for facilities and fleets.

 

environmental loads – Loads that are a result of the topography and/or the weather, such as seismic, snow, or wind loads.

 

epicenter – The part of the Earth’s surface that is directly above the disturbance (i.e. focus).

 

equipotential line – A line that is drawn on a flow net to represent points of equal total head.

 

erosion – The wearing away of the land surface by water or other geological agents.

 

estimating – A process of calculating the approximate amount of labor, equipment, and materials to perform a scope of work.

 

excavation – The process of removing earth material.

 

excess pore water pressures – Pressures that are greater than the hydrostatic values and that are generated by loading the soil.

 

excess rain fall – The portion of rain fall that exceeds the infiltration capacity and thus contributes directly to runoff.

 

expansion joint – A separation between parts of concrete that serves to accommodate heat-induced expansion and contraction.

 

expansive clay – Fine-grained, sensitive soil which exhibits a large increase in volume due to the addition of water.

 

Experience Modification Rate (EMR) – A rating that is assigned by OSHA to construction companies on the basis of their safety record. A high value indicates that the company sustains many accidents and injuries, and an EMR value of 1 is considered the industry average.

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extensometer – A device that is used to measure the movement of soil or rock along a single axis. Extensometers can be used to monitor tunnel displacements, deformations in rock faces, or linear displacements of structures.

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factor of safety – A term describing the structural capacity of a system beyond its loading capabilities. The factor of safety is based on the uncertainty with respect to material strength and loads.

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falling head test – A test used to estimate the permeability of soil by observing the rate that water falls in an observation well.

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falsework – Structures used for temporary support in order hold a component in place until the main work is strong enough to support itself.

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fast-track construction – The overlapping of the construction phase with the design phase (i.e. construction commences prior to the project plans and specifications being complete).

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fault – A fracture in the earth’s crust along which movement has occurred.

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fault gouge – Relatively coarse-grained rock that has been crushed and ground-up due to fault slips.

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fault scarp – A feature at the ground surface that resembles a step due to the movement along one side of a fault.

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fault trace – The intersection of a fault with the ground surface.

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field weld – A weld that is performed at the project site instead of at the fabricator’s shop.

 

fill – A deposit of earth material that is placed to raise the surface elevation.

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fillet weld – A weld that has a triangular cross-section at right angles and is used to join two pieces of metal together.

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filter strip – See buffer strip.

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fine-grained soils – Soils that possess clay or silt sized particles. Clays are significantly affected by changes in water content.

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fireproofing – The process of using noncombustible materials to make structural components more resistant to fire.

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first motion – The direction of the ground motion as the P-wave arrives at the seismometer.

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fissured clay – A clay that is intersected by cracks through which water can flow.

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fissures – Fractures or discontinuities in rock that allow groundwater to pass through.

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fixed fee – A set contract amount for all of the material, labor, and equipment that is required to perform a specific scope of work, and which includes the contractor’s overhead and profit.

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flat dilatometer test – A field test used to determine the strength or compressibility of soil, in addition to measuring parameters for lateral loads on deep foundations and low strain shear wave velocity. The procedure involves pushing a steel blade with an expandable membrane into the ground, and inflating the membrane to measure the pressure and deformation.

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fleet – A collection of vehicles or ships in a transport system.

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flexible pavement – Road surfacing that is created using layers of various asphalt mixes. An advantage of flexible pavement over rigid pavement is that it is fairly quieter when exposed to traffic.

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flexural strength – A material’s ability to resist bending under a given load.

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float – The amount of time a network path can be delayed from the early start without changing the completion date of the project. Float is also referred to as the contingency time that exists on a schedule of activities.

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flocculation – The process of fine particles binding together to form a larger clump.

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flood basin – A flat area between the bank and the sidehill that is subject to flooding.

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floodplain – The perimeter of low and flat land, near a stream or river, that may flood.

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flow duration curve – A graphical representation depicting the percentage of time that a particular flow in a stream is likely to equal or exceed a specified value of interest.

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flow net – A graphical representation used to study steady-state groundwater flow through soil. Grids are created by drawing a series of equipotential lines.

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flow rate – The rate at which water or wastewater travels through a given system.

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fluvial deposit – Sediment that has been deposited due to the nature of streams.

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focal depth – The depth of an earthquake hypocenter.

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focus – The place in the Earth where the earthquake originates.

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fold – A bend in layers of rock due to permanent deformation.

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footing – A shallow structural member constructed on soil or rock to provide support against loads.

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force account – A payment method used for extra work that covers labor, materials, and equipment.

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force pump – A pump that delivers fluids to an elevation higher than the pump itself.

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foreshocks – Smaller earthquakes that occur prior to the mainshock (i.e., the largest earthquake).

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formwork – Forms that are used to shape concrete.

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foundation – The lowest and supporting layer of a structure constructed on underlying soil or rock.

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fracture – A separation in a geologic formation, such as joints or fissures.

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Franki pile – A deep foundation element that is constructed using a heavy weight and a steel casing that is filled with a dry concrete mix. The heavy weight drives the casing into place, and afterwards, reinforcing steel and concrete are placed into the casing.

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free-body diagram – A representation of the relative magnitudes and directions of the forces that act upon an object.

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free float – The amount of time that an activity can be delayed without delaying the early start date of any activity that immediately follows it.

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free weir – A barrier that is not submerged.

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freeway – A divided highway with controlled access.

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freeze-thaw cycle – The repetitive process of water seeping into the voids of a material and freezing as a result of the temperature dropping below freezing, which in turn causes the water to expand. Afterwards, the ice melts back to water as the temperature rises.

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French drain – Perforated pipe, or a trench that is typically filled with gravel, that provides a passageway for water along a designated area.

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frequency – The number of occurrences of a repeating event during a particular period.

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friction angle – The ability of soil or rock grains to withstand a shear stress. The angle of internal friction measures the material’s frictional shear strength and can be determined from a direct shear test or a triaxial test.

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friction factor – A dimensionless factor that describes the friction losses in pipe flow.

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friction pile – A solid piece of material (i.e., timber, concrete, steel, etc.) that is mechanically driven into the ground, and which derives its load bearing capacity from the sides of the surrounding soil.

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frost heave – A phenomenon in which soil moves upward during freezing temperatures due to the formation of ice lenses.

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frost line – The lowest depth that the ground will freeze. Frost lines are used to dictate the depth that footings will be constructed and are specified in building codes.

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future value – The value of a stream of benefits or costs at a specific date.

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gabion – A cage filled with rocks, acting as a retaining wall.

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gage – The thickness of a sheet of steel.

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galvanized – A zinc coating that is applied on steel to prevent corrosion.

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gantry – An overhead structure that typically supports signs.

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Gantt chart – A type of bar chart that illustrates the schedule of activities for a project.

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gap – The time interval between the travel of consecutive vehicles that are moving in the same stream. The gap is measured between the rear of the vehicle that first traverses and the front of the subsequent vehicle.

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general conditions – A set of documents created by the owner that covers contractual obligations, including the minimum acceptable performance of the contractor.

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general contractor – An entity who performs either all or some of the work that is specified in the contract documents.

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geocell – A geosynthetic material taking the shape of a honeycomb-like structure, that when encased in soil or rock, provides erosion control or soil stabilization. Geocells are typically used to stabilize surfaces of eroded slopes, or to reinforce railroads or highways.

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geocomposite – A combination of geosynthetic materials, that when combined, can provide drainage, containment, reinforcement, filtration, and separation.

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geogrid – A geosynthetic material that is strong in tension, and is used to reinforce soil or rock. Geogrid layers are typically used for mechanically stabilized earth (MSE) wall systems, as well as for pavement stabilization.

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geonet – A geosynthetic material, having a netlike configuration, that provides drainage of liquids or gases. Unlike geogrids, geonets do not provide soil reinforcement.

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geophysical techniques – Various methods used to measure physical phenomena of the earth such as magnetism, gravity, and electrical and electromagnetic waves, without performing a subsurface investigation.

 

geosynthetics – Polymer products, such as geotextile, geogrids, geocells, and geofoam, that provide stabilization, drainage, or reinforcement when placed within soil or rock layers.

 

geotextile – A permeable or impermeable fabric that is typically used to provide separation, but can also provide filtration and reinforcement, and prevent erosion.

 

girder – The main supporting beam that supports other smaller horizontal supports.

 

glazing – The installation of glass into a prepared opening in windows or doors.

 

gorge – A deep, narrow passage with rocky sides, that is typically formed when a river flows through the wall of a canyon.

 

gouge – Thoroughly crushed rock within a fault zone.

 

graben – A block of land that has been dropped in relation to adjacent portions as a direct effect of faulting.

 

gradation – Assessing particle size distribution of granular materials by separating aggregate.

 

gradation test – See sieve analysis.

 

grade – The inclination of a particular surface to the horizontal. Also referred to as the slope of a roadway surface.

 

grade beam – A horizontal, reinforced concrete foundation member that transfers the load from a bearing wall directly to the soil or to a pile cap.

 

gradient – The rate of change with respect to distance.

 

grading – The act of changing the existing topography to create a level base or new slopes.

 

granular soil – Gravel, sand, or silt that does not have any cohesive strength and that crumbles easily when dry.

 

gravel – Granular material that is mostly retained on the No. 4 sieve.

 

gravity dam – A dam that primarily resists the forces of the water pressure by its own weight.

 

gravity wall – A wall that retains material solely by its own weight.

 

green construction – See sustainable construction.

 

ground improvement – A geotechnical construction technique in which the characteristics of soil are altered to allow for new construction projects.

 

groundwater table – The surface of the water that is located below the earth’s surface.

 

grout – A mixture of cement, water, and sand, that can be used for masonry construction or in geotechnical ground improvement applications.

 

grouting – The process of placing or injecting grout into the voids of soil or rock to improve the physical characteristics of the stratum.

 

Guaranteed Maximum Price (GMP) – A set maximum price that is negotiated between the owner and contractor, outlining the total construction cost and the fixed fee.

 

hardpan – A dense layer of soil, typically of glacial origin and mostly impervious, that is found at greater depths.

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harmonic tremor – A long and continuous release of seismic energy, which can be measured by instruments installed at the ground surface.

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haul distance – The most practical route from the center of mass of the original excavation to the center of mass of the location where it is ultimately placed.

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Hazen-Williams equation – An empirical relationship that calculates the pressure drop in pressure pipe systems due to friction.

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head loss – The decrease of water pressure in a hydraulic system.

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headwall – A concrete wall that is constructed at the outlet of a culvert or drainpipe.

 

headway – The time interval between consecutive vehicles traversing in the same stream, measured from the same point of each vehicle.

 

heave – The upward movement of structures due to either expansive soil or rock, or as a result of freezing temperatures.

 

heavy rail – Electric railway that has the capacity of handling a heavy volume of traffic.

 

heavy sludge – Residual material left over from wastewater that resembles fluid, yet has a low moisture content.

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helical pile – A steel shaft that has helical bearing plates, and when mechanically screwed into the ground, can serve as a deep foundation system.

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hertz – A unit of measurement that expresses the frequency in cycles per second.

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hierarchy – The arrangement, in order, of things or people.

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histograph – A chart or map of a drainage system, in addition to a series of time lines.

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hollow-stem auger – A device, which resembles a corkscrew, that consists of a hollow stem, and is attached to a drill rig, which in turn is used for geotechnical or environmental drilling.

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homogeneous – Consisting of uniform composition and structure.

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homogeneous earth dam – A dam that is constructed using one soil type.

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honeycomb – Voids that appear at the surface of concrete due to poor consolidation techniques.

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honorarium – Compensation to unsuccessful bidders on partial design work during the bidding process. Owners that utilize a design-build project delivery system often use honorariums as an incentive to persuade unsuccessful bidders to submit bids on future work.

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horizontal curve – A curve used in the geometric design of highways to change the alignment or direction. The four types of horizontal curves are compound, simple, spiral, and reverse.

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horst – A block of land that has been raised in relation to adjacent portions as a direct effect of faulting.

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Hveem Resistance Value Test – See R-value test.

 

hydration – The chemical reaction between water and cement that allows concrete to harden.

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hydraulic conductivity – The measure of the soil’s ability to allow water to flow through the pore spaces.

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hydraulic fill – Select material that is deposited by a flowing stream of water.

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hydraulic gradient – The slope of the hydraulic grade line in a fluid system.

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hydraulic head – The measurement of the free surface of a given body of water above a datum.

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hydraulic jump – A sudden and turbulent conveyance of water in open channel flow. This condition occurs from a point below the critical depth to a point above the critical depth, thus changing from supercritical to subcritical flow.

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hydrometer – An instrument that is used to measure the specific gravity of a fluid.

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hydrostatics – A branch of fluid mechanics that studies fluids at rest.

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hyetograph – A graphical representation (i.e., bar graph) of the distribution of rainfall over a specific time period.

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hypocenter – See focus.

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igneous rock – One of the three main rock types that was once volcanic.

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immediate settlement – The re-arrangement of coarse-grained soil particles due to immediate compression from an applied load.

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immiscible – The inability of liquids to mix together.

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impeller – A set of rotating vanes within a pump.

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impervious – Resistant in allowing water to pass through.

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imposed load – See live load.

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incidence rate – The total number of injuries and illnesses multiplied by 200,000 and divided by the number of hours worked by all the employees. The value of 200,000 hours represents the equivalent of 100 employees that have worked 40 hours/week, 50 weeks/year, and provides the standard base for evaluating incidence rates.

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inclinometer – An instrument used to measure subsurface movements and deformations. A vertical casing is typically installed in the ground and a probe is lowered into the casing to obtain readings over time.

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indemnification – The act of compensating for loss or damage, and/or providing security for financial reimbursement.

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index of plasticity – See plasticity index.

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indirect costs – Expenses that affect an organization as a whole and not just a specific product. Indirect costs include management, taxes, and support functions.

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infiltrate – To penetrate the pores of a material.

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inflation – A sustained increase in the price of goods and services, and expressed as a percentage per time.

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influent – Raw or partly treated water that flows into a facility.

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infrastructure – The basic structures and facilities that are required for the operation and growth of a society.

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ingress – The act of entering.

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injection well – A well that is used to direct water through a particular stratum to a deeper depth.

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inlet – A large opening to a storm drainage system.

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in-situ – The natural or original position of material.

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intangibles – Economic factors that cannot be easily evaluated in monetary terms.

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integrated project delivery – A project delivery system that utilizes a single multi-party relational contract between the owner, designer, and the constructor.

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intensity – A value that expresses the severity of an earthquake. In the United States, the commonly used scale to depict intensity is the Modified Mercalli scale.

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interceptor drain – A device with a filter, which serves to separate hazardous matter from normal waste, prior to transferring it into the disposal terminal.

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interest – The money that is paid in exchange for borrowing money.

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interface – A surface that serves as a boundary between two materials.

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intermediate earthquake – An earthquake whose focus is located between 70–300 km from the Earth’s surface.

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interplate earthquake – An earthquake that occurs at a plate boundary.

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interpolation – The technique of determining new data points within a range of known data points.

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intraplate earthquake – A rare earthquake that occurs in the interior of a tectonic plate.

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invert – The lowest portion of the internal cross section of a pipe or conduit.

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invoice – An itemized list that outlines materials or services and their respective charges.

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Iowa Borehole Shear Test (BST) – A field test that measures the in-situ drained shear strength of soils. Once a shear head is inserted into a borehole, it is expanded against the sidewalls, and after brief consolidation, the shear head is pulled upwards and measurements are obtained.

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isoseismal – A contour line illustrated on a map that connects points of equal intensity for a given earthquake.

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isotropic soil – A soil mass having essentially equal properties in all directions.

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jacking and boring – A trenchless technique used for horizontal drilling. This method allows underground utilities to be installed beneath roadways and other inaccessible areas.

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jam density – Density when both the speed and flow are zero.

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jetting – A technique of forcefully shooting liquid or gas through a nozzle.

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joist – A horizontal supporting member that acts to support a ceiling, floor, or deck.

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karst topography – A landscape that is formed by the dissolution of soluble rocks, and includes features such as sinkholes and caves.

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kicker – A supplementary structural member, typically installed at an angle, that is used to support a beam.

 

kinetic energy – The energy of moving a body due to its motion and mass.

 

kip – A unit of force equal to 1,000 lbs.

 

K-value – The measure of the thermal conductivity of a material.

 

lacustrine – Relating to a lake or lakes.

 

laminar flow – The flow of fluid in smooth and regular paths (i.e., parallel to the layers).

 

landfill – A designated site where a carefully designed structure is built for the disposal of waste materials between layers of earth. The primary purpose of landfills is to prevent contamination between the waste material and groundwater.

 

landslide – A phenomenon in which a large mass of soil or rock moves downhill and laterally due to gravity, and often is triggered by intense rainfall.

 

lap joint – A joint in which one piece overlaps another piece.

 

lap splice – A connection of two pieces of rebar by lapping the ends of the bars.

 

late finish date – The latest possible point in time that an activity can be completed without delaying the project finish date.

 

late start date – The latest possible point in time that an activity can begin without delaying the project finish date.

 

lateral earth pressure – Pressure that soil exerts in the horizontal direction. The three categories of lateral earth pressure are at-rest, active, and passive.

 

lateral erosion – The wearing away of the sidewalls of a stream or river.

 

lean concrete – A concrete mix that has a high water-cement ratio.

 

levee – A critical safety feature (i.e., man-made embankment) that is constructed in low-lying areas to prevent water from overflowing the banks during a flood.

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level of service (LOS) – A measure of the quality of traffic service. A level of service of A corresponds to free flow while a level of service of F corresponds to a constant traffic jam.

 

leveling course – A base layer of asphalt that is placed directly on top of the aggregate base course to eliminate surface irregularities.

 

lien – A claim over a piece of property to secure payment of unpaid debt.

 

life cycle costs – All costs, in terms of present value, associated with the full life span of a facility or system. Both capital and operations and maintenance costs are considered when determining the life cycle cost.

 

lift – A layer of soil that is placed, graded, and compacted to serve as structural fill.

 

lift station – A pump station with no significant amount of force main. The pumps lift the fluid from one gravity pipe line to another in relatively the same location.

 

light rail – A passenger train that is powered by electricity and operates along crowded city streets with frequent stops. A light rail can be distinguished from a commuter rail due to its tighter turning radius.

 

limestone – A sedimentary rock that is known to produce karst terrains due to its solubility in water.

 

limit equilibrium – A method of investigating the stability of a soil mass that could potentially slide due to gravity.

 

lintel – A horizontal structural member that supports a load over an opening.

 

liquefaction – A phenomenon where saturated, coarse-grained soil suddenly loses strength due to vibrations, such as an earthquake, causing the material to behave like a liquid.

 

liquid limit – The water content that represents the boundary between the liquid and the plastic state of a soil.

 

liquidated damages – Compensation (i.e., costs incurred to the owner) that is owed by the contractor as a result of failing to complete the project on time.

 

lithosphere – The outer solid part of the Earth.

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live loads – Loads that are moving and that are not caused by the members of a structure. Live loads are temporary or of short duration, and are also known as imposed loads.

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load-bearing wall – See bearing wall.

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load combination – The summation of certain load cases to perform a particular analysis.

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loam – A type of soil that primarily consists of silt and sand, and some clay. Loam is typically used in agricultural situations due to its high retention of nutrients.

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locked fault – A fault that continues to store strain for an extended period because of the high frictional resistance that prevents it from slipping.

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loess – A wind-deposited silt material.

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long-lead items – Material or equipment that has been identified as having an extended delivery time.

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longitudinal – The direction which extends along the long axis of a member.

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loose yard – A yard of material that is measured once it has been excavated.

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lost-day rate – See incidence rate.

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lot – An isolated quantity of material from a single source.

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Love waves – Seismic surface waves, traveling faster than Rayleigh waves, which produce a horizontal motion due to their particles moving side to side.

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lump-sum contract – An agreement where the owner pays the general contractor a fixed price, which includes overhead and profit, to perform a specified scope of work.

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machine foundation – A foundation that is provided for a vibrating and/or rotating machine. Types of machine foundations include block, box, wall, and framed.

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macropile – A deep foundation element constructed using a drill rig that advances a large-diameter steel pipe to a desired depth. Reinforcing steel is then inserted into the pipe, and afterwards a high-strength cement grout is pumped into the pipe.

 

magnetic particle testing – A non-destructive testing technique that is used to detect surface irregularities or discontinuities within metals.

 

magnitude – The measurement of the amount of energy that is released during an earthquake. The Richter scale is typically used to measure small earthquakes, while the moment magnitude scale is used to measure

medium to large earthquakes.

 

main shock – The largest earthquake in a sequence of earthquakes, which can be followed by aftershocks or preceded by foreshocks.

 

major arterial – A road that carries moderate to heavy volumes of traffic at moderate to high speeds.

 

major principle stress – The maximum normal stress that occurs in a soil element.

 

manometer – A device that uses a glass tube, filled with a liquid, for measuring pressure.

 

mantle – The layer of material that is between the crust and the outer core of the Earth.

 

margin of safety – See factor of safety.

 

marginal cost – The increase or decrease of the total cost that a firm produces as a result of changing production or a service by exactly one unit.

 

marsh – A type of wetland which has soft areas, along with a high concentration of grass, reeds, and shrubs.

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masonry construction – A form of construction in which individual units (i.e., concrete blocks) are laid and set in mortar. Reinforcing steel can be added within a set of units to provide additional stability.

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