glossary - nz transport agency · glossary see also list of abbreviations and acronyms on pp....

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AAADT (annual average daily traffic): the totalyearly traffic volume in both directions divided bythe number of days in the year, expressed as vehiclesper day (vpd).

ABRASION: the wearing away of the surface of anaggregate by mechanical action, includingtrafficking.Los Angeles Abrasion Test: a test of resistance toabrasion offered by an aggregate under specifiedconditions.

ABSORPTION: the process of water moleculespenetrating the interior of an aggregate particle.

ABUTMENT: an end support of a bridge or similarstructure.

ADDITIVE: any substance which is added in smallamounts to impart some particular property, e.g.to improve adhesion, lower the viscosity, or modifythe end properties.

ADHESION: the action by means of which a fluidsubstance, e.g. a bituminous binder, sticks to thesurface of a solid body, e.g. chip. It arises throughintermolecular attraction between the contactsurfaces.

ADHESION AGENT: any substance which is addedin small amounts to bituminous materials toimprove adhesion of the binder to aggregate in thepresence of water. May also be referred to as anAnti-stripping Agent.

ADSORPTION: the attachment of a substance tothe surface of a solid, such as an aggregate particle,by molecular attraction, e.g. condensation of wateron a chip surface.

AGGREGATE: a general term for discrete mineralparticles of specified size or size distribution, e.g.crushed rock, slag, gravel and sand.

G l o s s a r ySee also list of Abbreviations and Acronyms on pp. xiv-xv.

Note. The following interpretations of terms apply to chipsealing, irrespective of any meaning the wordsmay have for other topics.

Entries in CAPITALS are defined further as a separate entry.

Entries in italics are alternative terms that are not defined further.

Size may be: COARSE aggregate for material retainedon the 4.75 mm sieve; orFINE aggregate for material passing the 4.75 mmsieve. Also called CHIP.

AGO (Automotive Gas Oil): a petroleum distillateused to FLUX bituminous materials. Colloquiallyknown as Diesel Fuel.

AIR VOID: see VOID.

ALIGNMENT: the geometric form of the centreline,or other reference line, of the CARRIAGEWAY withrespect to the horizontal or vertical axes.

ALLIGATOR CRACKING: see CRACKING.

ALLUVIUM (n); ALLUVIAL (adj.): material (gravel,sand, silt) which has been carried by water anddeposited where the water velocity was insufficientto keep it moving. In roading, alluvial aggregatesusually refer to rounded river-borne aggregates.

ANIONIC EMULSION: a bituminous emulsionwhich has a negative charge conferred on eachbitumen droplet.

ANISOTROPIC: having properties that vary indifferent directions.

ANTI-FOAM AGENT: a substance, e.g. silicone oil,which when added to a bitumen will reduce surfacetension and hence reduce frothing tendency of hotbitumen in the presence of water.

ANTI-STRIPPING AGENT: see ADHESION AGENT.

AP, ALL PASSING; PAP, PREMIUM ALL PASSING:aggregate that passes through certain sized sieves.

APPLICATION RATE: For BINDER, the amount ofmaterial applied to a given area of road surface,expressed in litres per square metre ( /m2). ForCHIP, application rates are traditionally specifiedin terms of area per volume (m2/m3).

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AQUAPLANING: a condition occurring on a wetroad surface where the tyres of a moving vehiclelose contact with the road surface and ride on afilm of water. Vehicular control is lost. Also knownas Hydroplaning.

AREA-WIDE PAVEMENT TREATMENT (AWPT):usually refers to structural pavement treatmentsapplied to substantial lengths of roads, includinglarge areas requiring DIGOUT and replace, orRECYCLING.

ARTERIAL ROAD: a road that carries predominantlythrough-traffic from one region to another, and isa principal avenue of communication for trafficmovements.

ASPHALT: a natural or manufactured mixture inwhich bitumen is associated with inert mineralmatter.

ASPHALT (HOT MIXED); ASPHALT CONCRETE:see ASPHALTIC CONCRETE.

ASPHALT PLANT: see MIXING PLANT.

ASPHALTENE: a constituent of bitumen solublein carbon disulphide, but insoluble in a selectedparaffin hydrocarbon solvent such as n-heptane.

ASPHALTIC CONCRETE: a mixture of bituminousbinder and aggregate with or without mineral fillerproduced in a mixing plant. It is delivered, spreadand compacted while hot, for use in roadconstruction. Also known as Asphaltic ConcreteSurfacing.Where an asphaltic concrete is applied over existingchipseals, or constructed directly over a new chipseal,the chipseal is called a MEMBRANE SEAL and actsas waterproofing beneath the asphalt layer.

ASSET MANAGEMENT: the application ofengineering, financial and management practicesto optimise the LEVEL OF SERVICE of an asset,such as a road, in return for the most cost-effectivefinancial input.

ASSET MANAGEMENT SYSTEM: see PAVEMENTMANAGEMENT SYSTEM (PMS).

ATTERBERG LIMIT(S): set of arbitrarily definedboundary conditions in a material, e.g. SOIL, relatedto water content.• LIQUID and PLASTIC LIMITS – define the water

contents at which a material passes from liquid

to plastic state, and from plastic to semi-solidstate.

• SHRINKAGE LIMIT – the water content belowthe Plastic Limit when no further change involume (shrinkage) will take place.

• PLASTICITY INDEX – the numerical differencebetween the values of the Liquid and PlasticLimits of a material.

ATTRITION: the wear of chip used for roadmaking.It is measured by the Micro-Duval Attrition Test, inwhich pieces of chip are placed in a closed cylinder,rotated for a given time, and the loss of weightcaused by wear is recorded.

AVERAGE GREATEST DIMENSION (AGD): theaverage of the greatest dimension of a sample ofchips, aligned in their greatest dimension.

AVERAGE LEAST DIMENSION (ALD): the averageof the least dimension of a sample of chips. Theleast dimension of a chip is the distance betweentwo parallel plates in contact with the chip whenthe chip is placed so that the distance is a minimum.

AXLE LOAD: the load applied to a pavement bya single axle.

BBACKFILL: (noun) fill placed in an excavation.

BALLAST: broken stone of about 100 mm diameterused as a foundation course.

BANDAGING: a treatment for narrow cracks lessthan 5 mm wide. Hot binder is poured on to thecleaned pavement, spread to make a 2-3 mm thickby 75-100 mm wide bandage.

BARRIER: an obstruction placed to prevent accessto a particular area, e.g. prevent vehicles leaving aroad.

BASE: the base represents the uppermost structuralelement of a pavement and can either be asphalticconcrete or basecourse. See BASECOURSE.

BASECOURSE:• One or more layers of material usually constituting

the uppermost structural element of a pavementand on which the surfacing may be placed. Itmay be composed of fine crushed rock, naturalgravel, broken stone, stabilised material, asphaltor Portland cement concrete.


• A graded aggregate used in such a layer.

BATCH: a quantity of materials mixed at the sametime.

BATCH PLANT: see also MIXING PLANT.Equipment used to measure by mass or volumethe quantities of various ingredients to make upeach complete charge for an asphalt mixer.

BATTER: the uniform side slope of walls, banks,cuttings, etc. The amount of such slope or rake,usually expressed as a ratio of horizontal to vertical,distinct from GRADE.

BENCH: a ledge cut or formed in the batter of acutting or natural slope to provide greater securityagainst slips.

BENEFIT/COST RATIO (BCR): a ratio of the presentvalue of economic benefits derived by thecommunity from transport system improvementsover the present value costs of those improvements.

BENKELMAN BEAM: an instrument for measuringthe deflection of the surface of a pavement causedby the passage of a dual-tyred single axle carryinga standard axle load.

BERM:• A grassed area between the kerb and footpath

or between the footpath and boundary.

• The shoulder of a road.

• A narrow shelf, path or ledge formed typicallyat the top or bottom of an earth slope.

• A mound on the outer edge of a road above afill batter to protect the batter from erosion.

BIND (verb):• To hold or stick aggregate together in a mass.

• To fill the interstices of small stones or coarsegravels with finer material to provide mechanicaland physical binding.

BINDER: a general term for a viscous material usedto hold solid particles together as a coherent mass(e.g. bitumen, clay). In a chipseal, it is the waterproofadhesive viscous material that binds to both theexisting road surface and the sealing chips of thechipseal as a cohesive mass.

BINDER RISE: a natural action which occurs duringthe life of a chipseal that can cause flushing andbleeding.

BITUMEN: a viscous liquid or a solid, consistingessentially of hydrocarbons and their derivatives,which is soluble in trichloroethylene. It is almostnon-volatile and has thermoplastic properties, i.e.it softens gradually when heated and hardens whencooled. It is black or brown in colour, and haswaterproofing and adhesive properties. See alsoRESIDUAL BINDER.

BITUMEN BURNS CARD: a yellow card whichgives the correct treatment for bitumen burns. Itis attached to the victim when they go to the doctoror hospital in order to alert medical staff to thespecial treatment required.

BITUMEN DISTRIBUTOR: see DISTRIBUTOR.

BITUMEN EMULSION: a liquid in which asubstantial amount of bitumen or bituminousbinder is dispersed as fine droplets (the DISPERSEDPHASE) in water (the CONTINUOUS PHASE), andstabilised by means of one or more emulsifyingagents. It is available in two basic types, CATIONICand ANIONIC, and in several grades (Quick Break,Slow Break, or Stable Grades), according to the rapidityof BREAKING (setting).

BLEEDING: the extrusion of a bituminous binderonto the road surface, generally in hot weather. Itis distinguished from FLUSHING, which is a solidsmooth surface caused by binder rise that may bethe end result of Bleeding.

BLIND: (verb) to spread a thin layer of suitablematerial to absorb excess binder or to assist inremedying a slippery or loose condition, or to fillexcess surface voids.

BLOCK CRACKING: a pattern of cracking of apavement surface which appears as a series ofconnected rectangles.

BLOWN BITUMEN: bitumen produced byhardening the distillation residue of a crudepetroleum by blowing air or steam through it atelevated temperatures.

BOIL OVER: The rapid increase in volume causedby the presence of water in hot bitumen and thesubsequent overflow of bitumen from a tank. Maybe called a Foam Over. See also FLASHING.

BONY: lacking small particles; particularly on thesurface of an unsealed road surface or shoulder.


BOULDER: a rounded or sub-angular stone or pieceof rock of large size, usually larger than 300 mm.

BOUND MATERIAL or PAVEMENT: granularmaterial with particles bound together by bitumen,cement, lime, fly ash etc., to improve the strengthand stability properties of the aggregate.

BPN (BRITISH PENDULUM NUMBER): units ofsurface friction measured by the BPT.

BPT (BRITISH PENDULUM TESTER): device formeasuring the surface friction or SKID RESISTANCEof a pavement surface.

BREAKING: separation of particles of bituminousbinder (the DISPERSED PHASE) from the water (theCONTINUOUS PHASE) in a BITUMEN EMULSION,to form a continuous film. When this occurs, thecolour changes from brown to black.

BRIDGE: a structure designed to carry a road orpath over an obstacle by spanning it.

BROOM: a device for sweeping (used for Brooming)to:• remove dust and loose foreign material before

spraying a chipseal;

• uniformly distribute aggregate that has beenspread inconsistently;

• remove loose aggregate from completed chipseal.

BULK DENSITY: the mass of material (includingsolid particles and contained water) per unit volumeincluding voids.

BUND: watertight wall designed to contain anyliquids accidentally escaping from tanks, drums orother equipment caused by leaks, damage orincorrect operation.

CCALCINED BAUXITE: a very high PSV (high skidresistance) chip produced by heating bauxite orein a kiln. Applied as a high skid resistance roadsurfacing using epoxy or polyurethane as a binder.

CALIFORNIA BEARING RATIO, CBR: a ratioexpressed as a percentage between a test load anda standard load. A standardised testing procedure(initiated by Californian State HighwaysDepartment in 1929) for comparing the strengthsof basecourses for roads (and airfields).

CAMBER: the transverse convexity given to thesurface of a carriageway or footway.

CAPACITY: the maximum rate of flow at whichpersons or vehicles can reasonably be expected totraverse a point or uniform segment of a lane orroad during a given period of time under theprevailing road, traffic and control conditions.

CAPE SEAL: a two coat seal in which the first coatis a chipseal, and the second coat is a slurry sealapplied soon after (within 1-2 weeks) to fill thetexture of the chipseal.

CAPPING LAYER: a layer of material placed onthe road bed to provide a working platform forconstruction equipment, and not considered to bepart of the pavement.

CARCINOGENIC: capable of causing cancer.

CARRIAGEWAY: that portion of a road or bridgedevoted particularly to the use of vehicles, inclusiveof shoulders and auxiliary lanes. Divided roads areconsidered to have two carriageways. May be calledROADWAY.

CATCH DRAIN: a surface channel constructedalong the high side of a road or embankment,outside the batter to intercept surface water.

CATCH PIT: a concrete pit at the end of a waterchannel to settle out solids before the flow entersa pipe drain. Also known as a Gully trap, Mud tank,or Sump.

CATIONIC EMULSION: a bitumen emulsion whichhas a positive charge conferred on each bitumendroplet. See BITUMEN EMULSION, ANIONICEMULSION.

CEMENT: a general term for substances that bindaggregates. In concrete work it generally refers toPORTLAND CEMENT.

CEMENT CONCRETE PAVEMENT: a general termfor a PORTLAND CEMENT CONCRETE (PCC) rigidpavement.

CEMENT STABILISATION: the controlledapplication of CEMENT to improve the load-carrying capacity of a pavement layer (usually theBASECOURSE) or the SUBGRADE.

CENTISTOKE: the unit of kinematic viscosity


normally used to define binder viscosity. Onecentistoke (cSt) = 1 mm2/second. See also VISCOSITY.

CENTRELINE:• The line which defines the axis or alignment of

the centre of a road or other work.

• A marked line on the centre of the carriagewayseparating opposing traffic streams.

CHANNEL: the drain which accepts water directlyfrom the pavement. See also KERB & CHANNEL(K&C), SURFACE WATER CHANNEL.

CHIP: crushed aggregate of similar size, used forroad surfacing, particularly in chipsealing.Sizes range from 4.75 mm to 19 mm.

CHIP LOSS: loss of chips from a sealed surface.

CHIP ROLLOVER: chip is rolled out of its originalposition.

CHIP SPREADING: the action of spreading thechip over a binder film which has been sprayedonto the road surface.

CHIPSEAL: a WEARING COURSE consisting of alayer or layers of uniformly sized aggregate orsealing chip, spread over a film of freshly sprayedbinder and subsequently rolled into place. CalledSurface dressing in UK, Sprayed seal in Australia.

CLAY: very fine (<75mm) complex silicates formedby the natural decomposition of rocks. It shrinkson drying and expands on wetting.

CLAY INDEX: a measure (%) of the expandableclay minerals in the <75 m fraction in an aggregateor in a crushed rock powder.

COARSE AGGREGATE: a general term used todifferentiate between various sizes of aggregate,usually material retained on a 4.75 mm sieve.Includes Grades 3 and 2 (7.5-10 mm; 9.5-12 mmALD).

COHESION: the ability of a material to resist, bymeans of internal forces, the separation of itsconstituent particles.

COLD MIX: a mixture of bituminous binder, gradedcoarse and fine aggregate, with or without mineralfiller, produced warm or cold in a mixing plant. Itis delivered in a workable condition for stockpilingand ultimate spreading and compaction. The mixis spread and compacted cold. Also known asPREMIX.

COMBUSTIBLE: describes a material that, onceignited, is capable of self-sustained burning in air.

COMPACTION: the process of reducing the volumeof a material by inducing packing of its particlesto increase the density or reduce content of airvoids, by Rolling, Tamping or other mechanicalmeans.

CONDITION: a quantitative description of thecondition of an asset, often expressed through theresults of a survey of pavement defects. See alsoPAVEMENT RATING.

CONSISTENCY: a general term for the physicalstate of a semi-fluid or plastic material associatedwith its resistance to deformation or to flow.

CONSOLIDATION: the process by which earth orsoil reduces in volume over a period of time usuallyinvolving loss of water.

CONSTRUCTION JOINT: a joint made inconstruction to separate the mass of the work intoseveral portions for convenience of construction.

CONTINUOUS PHASE: the liquid (e.g. water) inwhich a substantial amount of bitumen or bitumenbinder is dispersed as fine droplets (the DISPERSEDPHASE) in a BITUMEN EMULSION.

COPOLYMER: a polymer that contains two or morekinds of monomer in the same molecule, e.g. SBS.

CORE: a cylinder drilled out of a pavement fortesting purposes.

CORRUGATION: a pavement defect consisting ofclosely spaced ripples running across the line oftraffic, generally where braking and accelerationof vehicles occurs.

COST EFFECTIVENESS: an economic measuredefined as the effectiveness of an action or treatmentin terms of present worth of life-cycle costs.

CRACKING:• Alligator cracking (or Crocodile cracking in

Australia): small semi-regular polyhedral shapedcontiguous areas of cracking.

• Block cracking: a pattern of cracking of apavement surface which appears as a series ofconnected rectangles.

• Reflective cracking: visible cracks in the pavementsurfacing, caused by propagation of cracks


through to the pavement surface from theunderlying pavement layer.

• Longitudinal and Transverse cracking: long cracksthat run along or across the road.

• Shrinkage cracking: cracks caused by shrinkageof old bituminous surfaces.

CRACK FILLING; CRACK SEALING: means offilling cracks, usually by BANDAGING.

CREEP:• Slow natural movement of a material.

• Slow plastic deformation of a material understress; measured by the Creep test.

CROSSFALL: the slope, at right angles to thealignment, of the surface of any part of thecarriageway.

CROSS SECTION: a vertical section, generally atright angles to the centreline. On drawings itcommonly shows the road to be constructed, or asconstructed.

CROWN: the highest point on the cross section ofa carriageway with two-way crossfall.

CRUSHED GRAVEL: a gravel in which all or mostof the particles have been crushed.

CRUSHER DUST: continuously graded finesremaining after removal of coarser (>5 mm)aggregate from crushed aggregate by screening.Dust or fines produced by crushing gravel or rock.

CULVERT: one or more adjacent pipes or enclosedchannels for conveying a watercourse or streambelow the formation level of a road.

CURE: to stiffen or harden by evaporation ofvolatile constituents or by chemical reaction toachieve the desired end state of a material, such aschipseal, emulsion or concrete.

CUT:• The depth from the natural surface of the ground

down to the subgrade level (see also CUTTING),

• To excavate.

CUT-OFF DRAIN: an interceptor drain constructedalong the top of a cutting or batter to preventsurface water running down the face.

CUTBACK BITUMEN (or CUTBACK) (noun): abitumen the viscosity of which has been temporarily

reduced by the addition of a volatile diluent(CUTTER), such as KEROSENE, to make it morefluid for ease of application.

CUTBACK (verb): to reduce temporarily theviscosity of a bituminous material by blending itwith a volatile material (CUTTER).

CUTTER (Cutter Stock): a volatile distillate addedto bitumen to temporarily reduce its viscosity, e.g.KEROSENE, Turpentine.

CUTTING:• The portion of the road where the finished road

surface is below the natural surface.

• The addition of a solvent, usually kerosene, tobitumen to reduce its viscosity.

CYCLE PATH: separate carriageway devoted to theuse of pedal cycles.

CYCLEWAY: portion of road or footpath devotedto the use of pedal cycles.

DDECIBEL (dB): a measure of sound. Sound ismeasured as a ratio of the pressure of the soundwaves to the pressure of the quietest sound justdetectable by the human ear. A decibel (dB) is1/10th of a Bel. Measures commonly used for levelsof sound are Leq, L10, Lmax.

DECK: the part of a bridge which directly carriestraffic loads.

DEFLECTION: the vertical elastic (recoverable)deformation of a pavement surface caused by theapplication of a load by the tyres of a standardaxle.

DEFLECTION BOWL: the depressed shapeproduced at the surface of a pavement when a loadis applied.

DEGRADATION: the wear and breakdown of anaggregate under compaction equipment or whilein service, and caused by rubbing or grinding withinthe mass.

DENSE-GRADED MIX: a bituminous mix madewith graded chip, with or without added mineralfiller and low in voids. It depends on grading forstability. See also OGEM, OGPA, SMA.


DENSIFICATION: reduction in voids and anincrease in dry density of an aggregate.

DEPRESSION: a road defect in which the roadsurface has sunk.

DESIGN LIFE: the period during which theperformance of a pavement or structure, e.g. ridingquality, is expected to remain acceptable.

DESIGN PERIOD: a period considered appropriateto the function of the road. It is used to determinethe total traffic for which the pavement is designed.

DESIGN PROCESS: process for arriving at a finaldesign for a transport project and normally dividedinto three distinct phases:1. Functional Design: preparation of the conceptual

design with enough detail to ensure that thedesign will function as intended.

2. Preliminary Design: finalised design in terms ofcalculations, specifications and estimates so thatall aspects of the design have been determined.See also PRELIMINARY ENGINEERING.

3. Documentation: preparation of plans anddocuments describing the design sufficiently forit to be constructed.

DESIGN SPEED: a speed fixed for the design ofminimum geometric features of a road.

DESIGN TRAFFIC: the cumulative traffic, expressedin terms of EQUIVALENT STANDARD AXLES (ESAs),predicted to use a road over the structural designlife of the pavement.

DESIGN VEHICLE: a hypothetical road vehiclewhose mass, dimensions and operatingcharacteristics are used to establish designrequirements.

DESIGN VOLUME: the number of vehiclesexpected to use a road, adopted for the purposesof geometric design, normally expressed as thenumber of vehicles per hour or per day.

DESIGN WATER CONTENT: the highest watercontent of the subgrade soil likely to be reachedfor a significant period during the design life ofthe road.

DESIGN YEAR: the predicted year in which thedesign traffic would be reached.

DIESEL FUEL: a petroleum distillate used as a FLUX

or CUTTER with bituminous materials. Also knownas AGO (Automotive Gas Oil).

DIGOUT: a pavement repair where soft or defect-ridden pavement is excavated and new basecoursematerial is added. Either a new first coat seal or asurfacing of hot mix asphalt is applied on top.

DILUENT: A substance which has the effect ofreducing viscosity when added to bitumen. Seealso CUTTER or FLUX.

DIPSTICK: a steel rod for direct measurement ofthe volume of binder in the tank (or DISTRIBUTOR).

DISCHARGE: the volumetric rate of water flow.

DISH CHANNEL: a channel with a shallowU-shaped cross-section.

DISPERSED PHASE: the bitumen or bitumen binderdispersed as fine droplets in the liquid (e.g. wateror CONTINUOUS PHASE) in a BITUMENEMULSION.

DISTRIBUTOR: also called Bitumen Distributor orBitumen Tank and Sprayer. It is built specifically forstoring hot bituminous BINDER at the correcttemperature for spraying.

DIVIDED ROAD; DIVIDED CARRIAGEWAY: aroad having a separate carriageway for traffictravelling in opposite directions.

DRAG: (noun) a simple towed frame used to re-distribute running course over an unsealed surface;(verb) to use a drag.

DRAG BROOM: a towed frame carrying severalbroom heads, used for levelling or re-distributingsealing chip.

DRAIN: a channel formed at the surface or a culvert,pipe or other similar construction for drainage, forintercepting and removing water.

DRAINAGE: natural or artificial means forintercepting and removing surface or subsurfacewater (usually by gravity).

DRIVEWAY: a defined area used by vehiclestravelling between a carriageway and a propertyadjacent or near to the road. Also called Access Way.

DROP OUT: a road fault where the downhill edgeof the pavement has slipped away.


DRUM PLANT or Continuous Plant: See MIXINGPLANT.

DRY DENSITY: ratio of the mass of dry material,after drying to constant mass at 105°C, to its undriedvolume. Also the weight of a dry unit volume ofa material.

DRYER: a rotating metal cylinder in whichaggregates (chip) are dried and heated by an oil orgas burner.

DRY LOCK SEAL: an application of small chip toa new chipseal, usually after some traffic has usedthe new seal. No binder is applied before spreadingthe dry lock chip.

dTIMS: Deighton’s Total Infrastructure ManagementSystem software program used for predictivemodelling of road deterioration.

DUCTILITY: the ability of a substance to undergoplastic deformation without breaking.

DUCTILITY TEST: a test to measure the extent towhich a standard-sized test piece of bitumen canbe elongated under specific test conditions, untilit passes a pre-set length or before it breaks.

DURABILITY: the ability of a material to continueto provide the service for which it is intended.

EEARTHWORKS: a general term to describe alloperations involved in loosening, removing anddepositing or compacting earth, soil, or rock.

EDGE BREAK: a road failure where the edge of theseal breaks away.

EDGE LINE: a line used to differentiate the outeredge of the traffic lanes from the shoulder.

EDGE RUTTING: a defect where ruts appear at theedge of the seal, usually in the unsealed shoulder.

ELASTICITY: the property of a material in whichdeformation is linearly related to load and isrecoverable.

ELASTOMER: an elastic material such as naturalor synthetic rubber, which is added to bitumen tomodify its performance as a binder.

elv (EQUIVALENT LIGHT VEHICLES): a conceptequating one heavy vehicle to 10 light vehicles orcars.

EMBANKMENT: a construction (usually of earthor stone) to raise the ground (or formation) levelabove the natural surface.

EMBEDMENT: the action of pushing the chipsdown into the binder or substrate.

EMULSION: see BITUMEN EMULSION.

ENRICHMENT SEAL: a light application ofbituminous binder, with or without a fine coverof chip, for the purpose of increasing the bindercontent of a road surface. Also called FOG COAT,REJUVENATING SEAL.

EQUILIBRIUM SKID RESISTANCE: the equilibriumlevel at which skid resistance stabilises. It is reachedafter polishing by traffic has reduced the initialMicrotexture (see TEXTURE) and SKID RESISTANCE.

EQUILIBRIUM SCRIM COEFFICIENT (ESC): acorrection applied to SCRIM data to adjust forbetween-year variations in SKID RESISTANCE.

EQUIVALENT STANDARD AXLE (ESA): thenumber of standard axle loads which are equivalentin damaging effect on a pavement to an 8.2 tonnedual-tyred standard given vehicle or axle loading.

EXCEPTION REPORT: a report on the assets whichare performing below the required LEVEL OFSERVICE, and are exceptions to an otherwisecompliant road network.

EXPANSION JOINT: a space between two parts ofa structure or pavement, formed to allow smallrelative movements with or without provision ofmeans to preserve functional continuity.

FFAILURE: a pavement is considered to be in a failedcondition when the surface has become distortedto the extent that it is no longer safe for vehicleuse.Chipseal Failure generally relates to either loss ofwaterproofness of the chipseal, endangering theintegrity of the underlying pavement; or loss ofchip; or loss of skid resistance through flushing orpolishing.


Pavement Failure generally relates to a pavementsurface which has become distorted to the extentthat it is no longer safe for vehicle use.

FALLING WEIGHT DEFLECTOMETER (FWD): adevice to measure surface deflection of a pavementunder a dynamic load in order to evaluate itsstructural adequacy.

FATIGUE: the deterioration of a pavement or a testspecimen caused by the action of repetitive loads.

FATIGUE CRACKING: a visible crack in theWEARING COURSE eventually resulting from thepropagation of cracks caused by fatigue in theunderlying pavement layer.

FATTING UP: the development of a pavementsurface containing an excess of bituminous binderor puddle-up fines. A colloquial name forFLUSHING, BLEEDING.

FATTY: containing an excess of binder or puddled-up fines.

FEATHER: to blend an asphaltic concrete patchinto the existing pavement surface.

FEATHER EDGE: the surface of the pavement layersbetween the shoulder hinge point and the subgradesurface.

FILL: see also EMBANKMENT.• The depth from the formation surface to the

natural surface.

• To deposit fill.

• Material that has been deposited in a fill area.

FILLER (MATERIAL): finely ground material, e.g.particles of rock, hydrated lime, Portland cementor other non-plastic mineral matter, predominantlyfiner than 0.075 mm added to asphaltic mixes orslurries to reduce air voids (by filling) and to stiffenthe binder.

FILTER FABRIC: a material which allows water topass through but prevents the passage of fines; atype of GEOTEXTILE.

FINE: in this book, FINE refers to the smaller chipsizes of Grades 4 (5.5-8.0 mm), 5 (4.75-9.5 mm),and 6 (6.7-15 mm).

FINES (FINE AGGREGATE; FINE CHIP): materialpassing the 4.75 mm sieve. ATTERBERG LIMIT testsare carried out on soils passing the 0.425 mm sieve.

FINE CRUSHED ROCK: a graded aggregate preparedby crushing rock for use as chip in pavementconstruction, normally 19.0 to 26.5 mm maximumsize.

FIRE POINT: the temperature at which sufficientvapour is given off by a flammable product, understandard test conditions, to ignite and continue toburn. This temperature is slightly higher than aFLASH POINT.

FIRST COAT SEAL: an initial seal on a preparedunsealed surface, which is usually a basecourse.

FLAKY AGGREGATE: particles which have onedimension considerably less than the other twodimensions making them elongated.

FLAME TUBE (FLAME TUBE HEATER): a meansof heating bitumen, normally applicable to smallersized vessels or tanks. It consists of an oil or gas-fired burner in a tube with a flue pipe and the tubeis immersed in the product to be heated.

FLAMMABLE: a combustible substance, solid,liquid, gas or vapour, which is easily ignited in air.The term is preferred to inflammable. The term non-flammable refers to substances which are not easilyignited but it does not necessarily indicate thatthey are non-combustible.

FLASHING (FLASH OFF): the rapid evolution ofvapour from volatile liquids or water.

FLASH POINT: the lowest temperature at whichthe application of a small flame in a prescribedmanner causes a vapour to ignite (flash). The flashpoint is usually measured using the ClevelandOpen Cup Method.

FLEXIBLE PAVEMENT: a pavement consisting ofan unbound granular basecourse with a top surfaceof chipseal or thin AC. The surfacing is less than45 mm thick. See also RIGID PAVEMENT.

FLUSHED SURFACE: a smooth pavement surfacecaused by the presence of binder.

FLUSHING: see also BINDER RISE, BLEEDING. Lossof Macrotexture (see TEXTURE), either throughpresence of solid binder high up around the sealingchip, or chip embedment, or chip loss.

FLUX: a relatively non-volatile distillate used asan additive which is blended with bitumen to


permanently or semi-permanently reduce theviscosity of the bitumen, e.g. AGO (diesel fuel).

FLUXED BITUMEN: a bitumen which has had itsviscosity reduced by the addition of a less volatilediluent (FLUX).

FLY ASH: a fine-grained waste product obtainedfrom the combustion of pulverised fuel in powerstations.

FOAMED BITUMEN: or Expanded Bitumen, is a hotbituminous binder which is temporarily convertedto a foamed state by the addition of about 2% (byweight of bitumen) of water in controlledconditions.

FOG COAT: a very light application of bindersprayed onto the road surface over an ageing coarse-textured chipseal. (It is not a PRIME.) Usually thebinder is emulsion with low bitumen content. Alsocalled ENRICHMENT SEAL, REJUVENATING SEAL.

FOOTPATH; FOOTWAY: a public way reserved forthe movement of pedestrians and manuallypropelled vehicles (e.g. prams); a pedestrian facilityon a bridge.

FORMATION: the surface of the finishedearthworks, excluding CUT, FILL or BATTERS.

FORMATION LEVEL: the general level of thesurface of the ground proposed or obtained oncompletion of the earthworks.

FORWARD WORKS PROGRAMME: the principaloutput of asset management, detailing specificmaintenance treatments required for TREATMENTLENGTHS on a road network. It covers the next 10years as a minimum, but 20 year programmes arecommon. The Current Work Programme is extractedfrom it.

FOUNDATION: the soil or rock on which a structurerests. Also known as SUBGRADE when under apavement.

FRETTING: see CHIP LOSS, RAVELLING,SCABBING, STRIPPING.

FRICTION COURSE: an obsolete term for a bitumenaggregate surfacing mix. See OGPA (Open-GradedPorous Asphalt).

FROST HEAVE: The movement of a pavement orsoil surface caused by expansion of water freezingwithin it.

FURNITURE: see ROAD FURNITURE.

FUSION POINT: the temperature at which asubstance liquefies, often referred to as a MeltingPoint.

GGABION: a rectangular wire-mesh cage filled withboulders, used to retain embankments and riverbanks.

GANGSPRAYER; GANGBAR: see SPRAYBAR.

GAP GRADED: an aggregate or chip with both fineand coarse material but without one or more ofthe intermediate size fractions. See also SINGLE-SIZED and WELL-GRADED Aggregate/ Chip.

GEOTEXTILE: a synthetic fabric composed offlexible polymeric materials, woven or unwoven,used in geotechnical or general engineering works,for strengthening, for retaining or restrictingmovement of water or sediment as a filter, e.g. inswamps, or as a strain absorbing membrane (SAM).

GEOTEXTILE SEAL: a seal constructed usually bya light application of binder, over which a geotextilefabric is laid. The fabric is sprayed with binder untilit is saturated. Chip is then spread, followed byrolling.

GRADE: has at least 6 definitions.1. The rate of longitudinal rise or fall of a

carriageway with respect to the horizontal,expressed as a ratio or as a percentage. Also calledGRADIENT.

2. To design the longitudinal profile of a road.

3. To shape or smooth an earth, gravel, or othersurface by means of a GRADER or similarimplement.

4. Bitumen penetration grades of 80/100, etc.

5. To arrange aggregates or other material inaccordance with particle sizes.

6. A designation given to the size of sealing chips,i.e. Grades 1, 2, 3, 4, 5, 6 (from TNZ M/6Specification for Sealing Chip).

GRADED AGGREGATE: aggregate having a wideand continuous distribution of sizes from coarseto fine, the largest size being several times largerthan the smallest size.


GRADER: a motor-powered wheeled machine witha blade mounted centrally between the axles, usedto shape road surfaces.

GRADIENT:• A length of carriageway sloping longitudinally.

• The rate of longitudinal rise or fall of acarriageway with respect to the horizontal,expressed as a ratio or as percentage (See alsoGRADE definition 1).

GRADING:• The operation of cutting and spreading material

with a grader (see also GRADE definition 3).

• The particle size distribution of a material (seealso GRADE definitions 5 and 6).

GRANULAR MATERIAL: material with a particlesize no finer than SAND.

GRASS VERGE: grass area on the side of a road.

GRAVEL: a mixture of non-cohesive mineralparticles occurring in natural deposits, generallypassing a 75 mm sieve with a substantial portionretained on the 4.75 mm sieve.

GREENFIELD DEVELOPMENT: a developmentfor roads or other structures which begins with alandscape that is in its natural state.

GRIT: fine angular mineral aggregate, usuallypassing a 4.75 mm sieve.

GROUND LEVEL: the reduced level of anyparticular point on the surface of the ground.

GROUND WATER: water flowing or lying underthe natural surface of the ground; contained in thesoil or rocks, below the WATER TABLE.

GROUTING: the operation of pouring or forcinga liquid binder, such as bitumen, into the intersticesof a pavement surface, a structure or a naturalformation, under the action of gravity or appliedpressure. Also used in concrete work.

GUARDRAIL: a rail erected to restrain vehicleswhich are out of control. Also called ROAD SAFETYBARRIER.

GULLY TRAP: see CATCH PIT.

HHAIR CRACK: a thin, narrow crevice or fissurerunning irregularly across the surface of a concreteor clay product, not penetrating deeply.

HAND SPRAYER: spraying equipment whichdischarges binder through a jet at the end of ahand-held lance.

HARDENING: in the short term, is the increase inviscosity as a freshly sprayed bituminous bindercools or cures. In the long term it is the ageing andoxidising of a bituminous binder.

HARDNESS: the resistance of a rock to scratchingor abrasion. Mineralogical hardness is by comparisonwith an arbitrary reference scale (Moh’s Scale ofHardness).In chipseal design, hardness of an existing seal orsubstrate is considered because sealing on a softsurface is undesirable.

HAZARD: a physical situation with significantpotential for human injury, damage to property,or damage to the environment. An occurrence,process, substance or situation that is an actual orpotential cause or source of harm.Significant Hazard: a hazard that is an actual orpotential cause or source of serious harm, or harmwhich depends on the frequency or extent ofexposure to the hazard, or harm which does notoccur or is not easily detectable until a significanttime after exposure.

HEAVE: upward movement of soil caused byexpansion or displacement resulting fromphenomena such as moisture absorption, removalof overburden, pile driving or frost.

HEAVY VEHICLE (Heavy Commercial VehicleHCV): rigid trucks with or without a trailer, orarticulated vehicle with at least three or four axles.A vehicle capable of being laden to a gross ladenweight exceeding 3.5 tonnes.

HIGH PRESSURE WATER TREATMENTS: acollective term for WATER BLASTING and WATERCUTTING. Jets are used to direct very fine streamsof water at the road to restore Macrotexture byremoving excess binder at the chipseal surface.They have replaced the pavement burner treatmentwhich has been phased out.


HIGHWAY: a principal road in a road system.

HORIZONTAL CURVE: a curve in the plane orhorizontal alignment of a carriageway.

HOT MIX ASPHALT (HMA): aggregate andbitumen heated and mixed while hot, transportedto the site of construction, laid and compactedwhile hot. See ASPHALTIC CONCRETE and PLANTMIX.

HOT WORK: work involving flames or equipmentwhich might cause ignition of any flammablevapours present.

HYDRATED LIME: see SLAKED LIME.

HYDROCARBON: a substance composed only ofmolecules of carbon and hydrogen.

HYDROPHILIC MATERIAL: material (e.g. aggregate)showing a relatively high affinity for water.

HYDROPHOBIC MATERIAL: material (e.g.bitumen) showing no affinity for water.

HYSTERESIS: in the context of SKID RESISTANCE,relates to the contribution of Macrotexture (seeTEXTURE) to skid resistance through the inelasticdeformation of a vehicle tyre, resulting in loss ofenergy.

IIGNITION POINT (IGNITION TEMPERATURE):the lowest temperature at which, under standardtest conditions, the vapour of a solid, liquid or gaswill take fire and continue to burn.

IGNITION SOURCES: accessible sources of heat orenergy capable of igniting flammable atmospheres.

IMPERMEABLE: cannot be penetrated by a fluidsuch as air or usually water.

IMPERVIOUS: relatively waterproof soils, such asclays, through which a fluid, e.g. air or water,cannot percolate or only very slowly.

INERT ATMOSPHERE: a virtually oxygen-freeatmosphere, usually of nitrogen or carbon dioxide,used to prevent oxidation or combustion.

INERT MATERIAL: a material which does notexhibit any binding or cementitious properties, oris not chemically reactive.

INFRASOUND: the low frequency component ofsound (below 20 Hz).

INITIAL BOILING POINT (IBP): the temperatureat which a distillate such as kerosene begins to boil.

IN-LINE BLENDING: blending, usually of diluentswith a bituminous binder, by addition of the diluentto the binder while it is being pumped through apipe.

IN SITU: a material, or operation carried out on amaterial, in place, e.g. its original position in thefield.

INTERCEPTOR DRAIN: a type of side drain thatprevents water from flowing towards the road, andis normally sited away from the road.

INTERMEDIATE COURSE: any course betweenthe base- and surface courses.

INTERSECTION: a place where two or more roadscross. Also called Node.

INVERT: the lowest portion of the internal surfaceof a drain or culvert.

ISOKINETIC: having equal rates of movement inall directions.

ISOTROPIC: having properties that are equal inall directions.

J KJUNCTION: a place where two or more roads meet.

KERB: a raised border of rigid material formed atthe edge of a carriageway or pavement.

KERB & CHANNEL (K&C): combined kerb anddrainage channel, to capture and discharge run-off.

KEROSENE: a hydrocarbon used as a DILUENT.

LLAKE ASPHALT: a natural bitumen found in well-defined surface deposits, e.g. Trinidad Lake asphalt.

LANDSLIDE: a movement of the surface of ahillside, generally resulting from natural causes.

LANE: see TRAFFIC LANE.


LANE LINE: a line (usually painted), other thanthe centreline which divides adjacent traffic lanes.

LATERAL FRICTION: the force which, whengenerated between the tyre and the road surface,assists a vehicle to maintain a centrifugal pathwhere a road changes direction.

LATEX: a naturally occurring rubber emulsion (i.e.the sap of the rubber tree).

LAYER: portion of a pavement course placed andcompacted as an entity.

LAYER INSTABILITY: inadequacy in the structuralperformance of multiple seal layers, where thecombined thickness is greater than 40 mm andmore than 12% binder is present in the layer.

LEVEL OF SERVICE: the outcome that the roadasset provides for the end user. It may be a fixedstandard (and not to be exceeded) or a desirabletarget.

LIFE: the time (in years) that a road surface remainsin service.

LIME MORTAR: a mixture of cement or lime withsand and water.

LIME STABILISATION: the controlled applicationof lime to improve the load-carrying capacity of apavement layer (usually the basecourse), or of thesubgrade.

LIMESTONE: calcium carbonate, CaCO3, sometimesused as a filler. The material from which burnt lime(CaO), QUICK LIME and SLAKED LIME are derived.

LINE OF SIGHT: the direct line or uninterruptedview between a driver and an object of specifiedheight above the carriageway in their lane of travel.

LINK: the portion of road between twoINTERSECTIONS (or nodes).

LIQUID BITUMEN: bitumen which is liquid at25°C, according to the penetration test.

LIQUID LIMIT: see ATTERBERG LIMIT(S). Themoisture content, as a % of its dry mass, at whicha material passes from the plastic to the liquid stateunder specified test conditions.

LIVELY: the state of being workable as applied topremix patching materials; bitumen that is in oron the road surface which still retains its original

properties, i.e. will liquefy in hot weather causingbleeding. The opposite of old oxidised inertbitumen.

LOCKED-IN TYPE SEAL: a WET LOCK or DRYLOCK SEAL.

LONGITUDINAL SECTION or PROFILE: the shapeof a pavement surface measured as vertical distancesfrom some datum parallel to the traffic. (See alsoTRANSVERSE PROFILE, CROSS SECTION andVERTICAL ALIGNMENT.)

MMACADAM: uniformly sized interlocking stones,bound with smaller stone, gravel, etc., which areforced into the gaps by brooming, watering androlling to form a road surface. The road may bewater-bound, cement-bound, or coated with (taror) bitumen. If the latter it is called Tarmacadamor Tarmac.

MACROTEXTURE: see TEXTURE.

MANHOLE: see SERVICE HOLE.

MARGINAL AGGREGATE: a local aggregate whichdoes not meet conventional aggregate specificationsbut is suitable for specific uses in a pavement.

MARKING: any line painted on the road to controltraffic movement or parking.

MATRIX: a mixture of binding material and fineaggregate in which larger aggregate is embeddedor held in place.

MAXIMUM DRY DENSITY: the dry density of asoil obtained by a specified amount of compactionat the OPTIMUM MOISTURE CONTENT.

MECHANICAL BOND: the bond obtained in aMACADAM or other pavement created by theinterlocking of angular fragments of aggregate.

MECHANISTIC ANALYSIS: a design procedurebased on stress analysis and on elastic materialbehaviour in pavements.

MEDIAN BARRIER; MEDIAN STRIP: see ROADSAFETY BARRIER.

MEDIUM COMMERCIAL VEHICLE (MCV): two-axle heavy trucks without a trailer, over 3.5 tonnesgross laden weight.


MELTING POINT: see FUSION POINT.

MEMBRANE SEAL: a seal composed of straight-run BITUMEN, with little or no CUTBACK, and alight covering of chip. Covered soon afterconstruction with ASPHALTIC CONCRETE.

MICROSURFACING: a surface dressing comprisinga specially graded aggregate mixed with a polymermodified emulsion (PME) binder (of 3% maximumpolymer). See also SLURRY SEAL.

MICROTEXTURE: see TEXTURE.

MIX: the proportions of ingredients in a batch ofconcrete or asphalt.

MIXING PLANT (ASPHALT PLANT): equipmentused to manufacture hot asphalt mixes.

MODIFICATION: the improvement of propertiesof a material by the addition of small quantities ofadditive, e.g. lime, cement, for stabilisation.

MODULUS: a ratio of the stress (force per unitarea) to strain (deformation per unit area), expressedin units of stress. It is a measure of a material’sresistance to deformation.For bitumens, the modulus depends on both thetemperature and the time the load is applied. Inloading conditions that give rise to non-permanentdeformations (i.e. material returns to its originaldimensions) the resulting modulus is Young’smodulus (E), or the Modulus of Elasticity.

MOISTURE CONTENT: see WATER CONTENT.

MOTORWAY: a defined class of road for whichcertain activities or uses are restricted or prohibitedby legislative provision. Also called Expressway,Freeway.

MPD (MEAN PROFILE DEPTH) (mm): the measureof texture given by SCRIM+ and Transit NewZealand’s STATIONARY LASER PROFILER (SLP).

MSSC: Mean Summer SCRIM Coefficient.

MTD (MEAN TEXTURE DEPTH) (mm): thevolumetric patch test using glass spheres of 0.15to 0.3 mm diameter.

MULTICOAT SEAL: a two coat chipseal, and otherchipseals, having more than one layer of chip.

MULTIPLE LANE: a carriageway with more thanone traffic lane.

MULTIPLE SEAL: any seal with two or more layers,e.g. TWO COAT, RACKED-IN, and SANDWICHseals.

NNAASRA: National Association of Australian StateRoad Authorities; superseded by Austroads.

NATURAL ASPHALT: a naturally occurring bitumen,e.g. Trinidad Lake Asphalt.

NOMINAL SIZE: a designation of an aggregate,chosen to give an indication of the largest sizedparticle present.

NORMAL CROSS SECTION: the cross section ofthe carriageway where it is not affected bysuperelevation or widening.

NORSEMETER RoAR: a machine for measuringskid resistance.

NUCLEAR DENSOMETER: an instrument for thenon-destructive measurement of the density andmoisture content of pavement layers.

OOGEM, OPEN GRADED EMULSION MIX: seeOGPA for comparable description.

OGPA, OPEN GRADED POROUS ASPHALT: a gap-graded hot mixed asphalt containing a mix ofbinder and larger sized aggregates with only smallamounts of fine material, with relatively high voidcontent, and depending largely on mechanicalinterlock for stability. It has interconnected voidswhich aid drainage of road surface water.

OPTIMUM MOISTURE CONTENT (OMC): themoisture content at which a specified amount ofcompaction will produce the maximum densityunder specified test conditions.

OVERBURDEN: soil or other material which hasto be removed to enable the material beneath it tobe quarried or excavated.

OVERLAY: a layer of material constructed on topof an existing pavement to improve its shape orincrease the strength.


PPAH: polycyclic aromatic hydrocarbons.

PAP (PREMIUM ALL PASSING): see AP (ALLPASSING).

PARTICLE SIZE: the diameter of the aggregate orchip particle, i.e. minimum square-hole sieveopening that allows the particle to pass through.

PARTICLE SIZE DISTRIBUTION (psd): theproportion by weight of particles of different sizesin a granular material (aggregate, chip) asdetermined by sieve analysis. See also GRADE,GRADING.

PATCHING: the repair of depressions, holes orother defective places in a pavement by addingmaterial to restore the surface.

PAVEMENT:• The portion of the road, excluding shoulders,

that is placed above the design subgrade levelfor the support of, and to form a running surfacefor, vehicular traffic. It is supported by thesubgrade.

• Also used to describe the sealed area of thefootpath or other sealed areas.

PAVEMENT DISTRESS: the deterioration of thepavement shown by visible surface defects.

PAVEMENT MANAGEMENT SYSTEM (PMS): asystematic method of information collection anddecision making, to permit the optimisation of useof resources for maintenance and rehabilitation ofpavements.

PAVEMENT PERFORMANCE: the relationship ofserviceability to age of the pavement.

PAVEMENT RATING: a method of systematicallydescribing the condition of a pavement, usuallyby visual inspection.

PAVEMENT SERVICEABILITY: the measure of thepavement’s ability to serve its function at any time.

PENETRATION GRADE: determines the hardnessof a roading bitumen by measuring the distancein tenths of a millimetre that a standard needleweighted with 100 g will sink (penetrate) in5 seconds into a bitumen sample, at 25°C.

PENETRATION GRADE BITUMEN: a bitumencompliant with the required specification andnamed for its penetration grade. It is produced byvacuum distillation usually, followed in some casesby solvent extraction or a partial oxidation process.Such bitumens are principally used for roadsurfacing or industrial applications.

PERMEABILITY: the property of an aggregatewhich permits a fluid, e.g. air or water, to passthrough it when subjected to pressure.

PERMIT TO WORK: a document issued by anauthorised person or persons permitting specificwork to be carried out in a defined area during astated period of time, provided that specified safetyprecautions are taken.

PERSONAL PROTECTIVE EQUIPMENT (PPE):includes high visibility vest, hard hat, gauntletgloves, flame-retardant overalls, boots, and specialistprotective equipment appropriate to the job inhand.

PERVIOUS: describes a material through whichwater can pass.

PITCH: the solid or semi-solid residue from thepartial distillation or evaporation of oils from coaltar. (Not to be confused with BITUMEN.)

PIT-RUN GRAVEL: material obtained from a naturaldeposit of gravel without separation or addition ofother material.

PLANT MIX: a general term for mixtures ofbituminous binder and aggregate produced in acentral mixing plant. See also PREMIX.

PLASTIC LIMIT: see ATTERBERG LIMIT(S). themoisture content, expressed as % of dry mass, atwhich a material passes from the plastic to thenon-plastic state, under specified test conditions.

PLASTIC MATERIAL: a material in a conditionwhen it can be easily remoulded.

PLASTICITY INDEX: see ATTERBERG LIMIT(S). Thenumerical difference between the values of theLIQUID LIMIT and the PLASTIC LIMIT of a material.

PMB (POLYMER MODIFIED BITUMEN): abitumen with polymer added, usually up to 5-6%by mass. Polymers tend to reduce the temperaturesensitivity of the binder, and some polymers makethe binder more elastic.


PME (POLYMER MODIFIED EMULSION): apolymer-modified bitumen that has beenemulsified.

POLISHED STONE VALUE (PSV): a measure ofhow a stone will polish under standard conditions.The PSV test is primarily used to identify aggregates(chip) that will retain their microtexture (i.e. willnot polish) under traffic.

POLISHING: the action of vehicle tyres and fineroad detritus on road surface chips which smoothsthe surface.

POLYMER: high molecular weight, usually organic,compound made up of many units, identical toeach other (monomers), and joined in a regular way,e.g. polypropylene. Some polymers may be usedto permanently modify bitumen. Usually polymersprovide improved temperature/ viscosity responseand/or greater fatigue resistance.Copolymer: a polymer that contains two or morekinds of monomer in the same molecule, e.g.Styrene-butadiene rubber SBR, Styrene-butadienestyrene SBS.

POLYMER MODIFIED BITUMEN; POLYMERMODIFIED EMULSION: see PMB, PME.

POROSITY: ratio of the volume of voids in amaterial to its total volume.

PORTLAND CEMENT: an artificial cement asdefined in AS 1315. Usually called CEMENT.

PORTLAND CEMENT CONCRETE (PCC): concretein which the binding material is PORTLANDCEMENT. Usually called Concrete.

POTHOLE: a hole in the pavement, frequentlyround in shape, resulting from loss of pavementmaterial caused by the action of traffic.

PPE: see PERSONAL PROTECTIVE EQUIPMENT.

PRECOATING: coating an aggregate with abituminous material to improve the rate at whichit is wetted, or to improve the adhesion of abituminous binder.

PRELIMINARY ENGINEERING: work of locatingand designing, making surveys and maps, preparingspecifications and estimates, and doing otherengineering work before letting a contract forconstruction of a transport project. See also DESIGNPROCESS.

PREMIX: a mixture of bitumen and chip, usuallystored in a stockpile and used for patching.

PREP; PREPARATION; PRE-SEAL REPAIR: anyactivity undertaken in the period up to a year beforechipsealing, to prepare the surface for the chipseal,e.g. DIGOUT, CRACK FILLING, lichen removal.

PRETREATMENT SEAL: treatment applied to asurface as a pretreatment, e.g. for reducing texturevariance. See also TEXTURISING SEAL.

PRIME; PRIMER; PRIME COAT: a low viscosity,fluid, bituminous material applied to a preparedbase without cover aggregate, before the initialapplication of a seal. Used to improve penetrationof the binder into the base surface, to wet anysurface dust layer, and to adhere to the stonebeneath. Not used often in New Zealand.

PROFILE: the shape of a pavement layer or surfacemeasured in a vertical plane, from a datum, parallelto the traffic flow, or at right angles or transverseto the traffic flow.

PUBLIC ROAD: a public place which has beenprovided for use by the public for traffic movementand has been declared, or proclaimed, notified ordedicated.

PUMPING: the ejection of water and fine particlesin suspension through joints or cracks in apavement caused by the action of traffic, or byground water pressure.

QQUALITY ASSURANCE (QA): all planned andsystematic actions necessary to provide adequateconfidence that a product or service will satisfygiven requirements as to the quality of a product.

QUALITY CONTROL: the operational techniquesand activities that are used to fulfil definedrequirements for quality production.

QUARRY: an open-surface working from whichrock is obtained.

QUARRY DUST or FINES: the finest sized materialmost of which passes a 4.75 mm sieve, producedfrom a crushing or screening plant. Also known asCRUSHER DUST.

QUARRY WASTE: reject material from a crushingor screening plant containing a wide range ofaggregate or chip sizes.


QUICK LIME: calcium oxide, CaO, used as anadditive (with granular form) in soil stabilisation.Also referred to as Burnt Lime.

RRACKED-IN CHIPSEAL: one application of binderand two applications of chip are made in thefollowing sequence:• A single application of binder is applied, followed

by application of a large chip;

• A further application of a smaller chip is made.

The first application of large chip has spaces intowhich the smaller chip can fall between the largechip, and adhere to the layer of binder below.

RAISED PAVEMENT MARKER (RPM): a deviceused to supplement or replace traffic lines on theroad surface. It may be reflectorised (RRPM).

RAMM (Road Assessment and MaintenanceManagement system): a computer-based systemto manage the maintenance and rehabilitation ofpavements and associated roading features.

RAP (Reclaimed Asphalt Pavement): obtainedfrom milling or excavation of asphalt pavements.The crushed and graded product can be addedduring manufacture and included as a percentageof a new asphaltic concrete.

RATING: see PAVEMENT RATING.

RAVELLING: the loosening of aggregate from thesurface of a pavement. Also called CHIP LOSS,Fretting, SCABBING, STRIPPING.

RCA or ROAD CONTROLLING AUTHORITY: theauthorities responsible for roading within theirjurisdiction, e.g. Transit New Zealand for thenational State Highway system; District or CityCouncils for roads within Local Government regionsincluding roads within urban boundaries.

RECYCLING: re-using existing materials orincorporating waste materials such as glass, tyres,slag.

RE-CIRCULATION: pumping binder from a tank,through a pipe system and back to the tank.

REFLECTIVE CRACKING: visible cracks in thepavement surface, caused by propagation of cracksthrough to the pavement surface from theunderlying pavement layer.

REFLECTORISED RAISED PAVEMENT MARKER(RRPM): a RAISED PAVEMENT MARKER withreflectors, fixed in a CARRIAGEWAY.

REHABILITATION: an area treatment that restoresa distressed pavement to improve its serviceabilityfor a further design period. Usually it is a completeexcavation and replacement of basecourse andsurfacing for an entire TREATMENT LENGTH.

REINFORCEMENT (reinforced concrete): steel rods,bars or other reinforcing materials, embedded inconcrete, masonry or brickwork, for the purposeof resisting particular stresses.

REJUVENATING SEAL: a seal composed of a lightapplication of binder, with no chip, and sprayedover an ageing coarse-textured chipseal. Usuallythe binder is emulsion with low bitumen content.Also called FOG COAT or ENRICHMENT SEAL.

RESEAL: a seal applied to an existing sealed, asphalt,concrete or timber surface. Also known asResurfacing.

RESIDUAL BINDER: the non-volatile fraction ofa binder that remains in service after evaporationof volatiles.

RESILIENT MODULUS: ratio of stress to recoverablestrain under repeated loading conditions. Alsoreferred to as Elastic Stiffness.

RHEOLOGY: the science of the flow of matter.Effectively the study and evaluation oftime–temperature dependent responses of materials,e.g. bitumen, that are stressed or subjected to anapplied force. Rheological properties of bitumeninclude: age hardening, ductility, penetration,temperature susceptibility, shear susceptibility,stiffness, viscosity.

RIGID PAVEMENT: a pavement constructed ofPortland cement concrete or several layers ofstructural asphalt, generally 110 mm or more thick.See also FLEXIBLE PAVEMENT.

RIPRAP: medium to large sized rocks placed toprotect a structure (e.g. a bridge) against scour.

RISK: the likelihood of human injury, damage toproperty, or damage to the environment, from aspecified hazard, weighted against probability andconsequence.


ROAD: a route trafficable by motor vehicles. Inlaw, it is the public right-of-way between theboundaries of adjoining properties. It is owned oradministered by an RCA.

ROAD CAPACITY: see CAPACITY.

ROAD CATEGORY: Urban Arterial – in urban areaswith traffic volumes >7000vpd; Urban Other – carry<7000 vpd; Rural Strategic – connect main centresand carry >2500 vpd; Rural Other – other roadsoutside urban areas. See Transfund NZ’s ProjectEvaluation Manual (2002) Appendix A2.2.1 fordetails, and Land Transport Rule (2002) VehicleDimensions and Mass for latest information.

ROAD CLASSIFICATION: consistent terminologyand designation of roads to provide a basis forplanning and decision making by national andlocal government agencies responsible for variousaspects of road administration.

ROAD FURNITURE: a general term covering allsigns and devices for the control, guidance andsafety of traffic, and the convenience of road users,e.g. barriers, GUARDRAILS, lighting, parking meters,poles and posts, all signs and traffic lights.

ROAD GEOMETRY: the overall shape of the road.

ROAD HIERARCHY: the grading of roads accordingto increasing or decreasing importance of theirtraffic-carrying or other function. See also ROADCATEGORY.

ROAD INVENTORY: schedule of all road character-istics, i.e. control devices, parking restrictions, roadwidths, number of traffic lanes, etc.

ROAD MAINTENANCE: the work required to keepa road at its specified level of service. It includeswork on the road structure, furniture and drainagesystem. The work tends to be piecemeal rather thanlarge scale works, as it is carried out as requiredthroughout the year.

ROAD MARKING: a line painted on the road tocontrol traffic movement or parking.

ROAD RESERVE:• A legally described area within which facilities

such as roads, footpaths and associated featuresmay be constructed for public travel. Often calleda road.

• The entire right-of-way devoted to public travel,including footpaths, verges and carriageways.

ROAD SAFETY BARRIER: a rail or fence erectedto restrain vehicles which are out of control. Seealso GUARDRAIL.

ROADWAY: the portion of a road or bridge devotedparticularly to the use of travelling vehicles,inclusive of shoulders and auxiliary lanes. A dividedroad has two roadways. See also CARRIAGEWAY.

ROAD WORKS: a general term for any work on aroad for construction, repair or maintenance.

RoAR (NORSEMETER): a machine used to measureSKID RESISTANCE of a pavement surface.

ROCK: a term used generally to describe a stonelarger than about 150 mm.A geological term to describe a kind of mineralmatter, e.g. igneous rock, sedimentary rock.

ROLLER: an item of equipment designed tocompact soil and pavement layers, such aspneumatic-tyred, rubber-coated vibrating drum,or combination rollers.

ROLLING: see COMPACTION.

ROLL OVER: see CHIP ROLLOVER.

ROUNDABOUT: an intersection of two or morecarriageways at a common level, where all traffictravels in one direction around a central island(usually circular), to induce weaving movementsin lieu of direct crossings.

ROUGHNESS: the consequence of irregularities inthe longitudinal profile of a road with respect tothe intended profile. It is measured by theunidirectional displacement of a standard (NAASRA)test vehicle (ROUGHNESS METER) relative to itsaxle, as the vehicle travels over the surface at astandard speed.

ROUGHNESS METER: a device for measuringvehicle response to roughness. Traditional devicesmeasure the vertical displacement of an axle to avehicle body, as the vehicle travels over the surfaceat a standard speed. Modern roughness meters uselasers to measure road surface texture. May be aRoughometer, a (NAASRA) Roughness Response Meter,or Laser Profilometer.

RUBBER: naturally occurring polymer of isoprene.Available as an emulsion called LATEX.

RUNNING COURSE: a thin layer of loose stonewhich protects the surface of an unsealed road.


RUN-OFF:• A general term for water (normally from rainfall)

flowing across the surface of the ground.

• The amount of water precipitated onto acatchment area which flows as surface dischargefrom the catchment area past a specified point.

RUT: a longitudinal depression in a pavementcaused by the passage of the wheels of vehicles.

RUTTING: the longitudinal vertical deformationof a pavement surface, measured at right angles tothe traffic flow and across the wheelpath.

SSAM (Stress Absorbing Membrane): a chipseal,which may be a single coat, two coat, or racked-inseal, that uses a PMB (Polymer modified binder).

SAMI (Stress Absorbing Membrane Interlayer):usually constructed with a PMB and a singlecovering of chip. An asphaltic mix surfacing is thenconstructed on top.

SAMPLE: a representative portion of a material,such as aggregate.

SAMPLING: the selection of a representative portionof a material, such as aggregate, for the purpose ofascertaining its characteristics.

SAND: natural mineral particles which pass througha defined sieve, e.g. 4.75 mm or 2.36 mm sieves,and are retained on a 0.075 mm sieve. Free ofappreciable quantities of clay and silt.

SAND CIRCLE: a test used to determine the averagetexture depth of a pavement surface. A circle ismade with a standard volume of sand, and itsdiameter relates to the volume of voids. The testis in accordance with TNZ T/3 Specification:Measurement of texture by the Sand Circle Method.

SANDWICH SEAL: a seal applied as a layer of largechip spread directly on the existing surface followedby a relatively light application of binder. A finerchip is then spread directly onto the sprayed binder,and rolled to compact the seal.

SBR Styrene-butadiene rubber: a polymer usedfor modifying bitumen.

SBS Styrene-butadiene-styrene: a polymer usedfor modifying bitumen.

SCABBING: loss of patches of chips from a chipseal.See also CHIP LOSS, Fretting, RAVELLING,STRIPPING.

SCALPING: a process in a quarry crushing plantwhere separation of two grades of rock takes place.The removal of unwanted material using grizzlybars from excavated rock before crushing.

SCARIFYING: the systematic disruption andloosening of the top of a pavement or of naturalground by mechanical or other means.

SCREED: (noun) strip of wood or metal which isused to strike off or finish a surface to the requiredshape or texture; (verb) to carry out this action.

SCREEN: a large sieve usually mechanicallyoperated, used to separate material by size. Thesieving surface may be either flat or cylindrical inform.

SCREENINGS: aggregate or chip of small size,usually passing a 26.5 mm sieve and retained ona 4.75 mm sieve.

SCRIM or Sideway force Coefficient RoutineInvestigation Machine: a machine used to measurewheelpath skid resistance.

SCRIM+: a SCRIM machine with additionalequipment to measure road condition (e.g.roughness, rutting & texture) and road geometry,in addition to wheelpath skid resistance.

SEAL: a thin layer of bituminous binder sprayedonto a pavement surface which prevents waterentering the underlying pavement and having alayer of aggregate rolled in. Depending on theapplication sequence, seals are referred to as firstcoat, second coat, and reseals. See also CHIPSEAL.

SEAL COAT: a bituminous waterproofing layer onthe surface of a pavement.

SEALED SHOULDER: that portion of the sealedcarriageway beyond the traffic lane, located betweenthe traffic lane edge line and the edge of the seal,generally flush and contiguous with the sealedcarriageway. See also SHOULDER.

SEALING CHIP: see AGGREGATE, CHIP, andGRADE (definition 6).

SEASONAL VARIATION: the fluctuation in skidresistance after the equilibrium level has been


reached, in which it tends to increase in winterand decrease in summer.

SECOND COAT SEAL: previously, the term givento a seal placed on top of a primed or first coatsealed surface and before subsequent reseals. Theterm is obsolete as all second coat seals are nowconsidered as RESEALS.

SEEPAGE: small quantities of water percolatingthrough a porous material.

SEGREGATION: separation of coarse aggregatefrom fine material or from the rest of a bituminousmix. Liable to occur in stockpiles of aggregates, orduring transportation of aggregate or hot mix.

SELECTED FILL: fill complying with specifiedrequirements.

SERVICEABILITY: the degree to which a facilitysuch as a road meets relevant requirements orstandards.

SERVICE HOLE: a shaft with a removable coverthat leads down to a sewer, drain or otherunderground service. Also called Manhole.

SET UP: to harden or cure by evaporation ofvolatiles, e.g. of a cutback binder.

SETTLEMENT: a downward movement of the soilor of the structure it supports by the reduction ofthe voids in the underlying material.

SFC or SIDEWAY-FORCE COEFFICIENT: the ratioof the resistance to sideways motion of the tyre ofa vehicle (on a specified pavement) and the normalforce on that wheel related to the vehicle’s mass.SCRIM machines measure this force.

SHALE: sedimentary argillaceous rock characterisedby, or able to be split into, thin laminae.

SHALLOW SHEAR: a defect occurring where anupper pavement layer loses stability and shoves. Itis caused by vehicle loading.

SHAPE CORRECTION: correcting the longitudinalor cross-sectional shape of a road, using anOVERLAY.

SHEAR FAILURE: a form of failure in a materialwhen the shear stress exceeds the available shearstrength on a plane.

SHEAR STRENGTH: the maximum shear stressthat the mass of material can withstand under aspecified set of loading conditions. It is controlledby normal pressure on the shear plane, drainageconditions, or rate of strain. It is a function of theeffective stress, cohesion and the angle of shearingresistance.

SHOULDER: the portion of the carriageway beyondthe traffic lanes that is contiguous and flush withthe surface of the pavement.

SHOULDER HINGE POINT: the point in a crosssection of a road at which a side slope wouldintersect with the unsealed shoulder or, in theabsence of an unsealed shoulder, the sealedshoulder.

SHOVING: lateral displacement of the pavementstructure caused by braking, accelerating or turningvehicles.

SHRINKAGE: volume change in either the base,subgrade or occasionally in the asphalt mix.

SHRINKAGE CRACKS: interconnected cracksforming a series of large blocks, usually with sharpangles. Frequently caused by volume change orSHRINKAGE.

SHRINKAGE LIMIT: see ATTERBERG LIMIT(S).

SIDE CHANNEL: see SURFACE WATER CHANNEL.

SIDE DRAIN: a longitudinal surface drain or ditchusually U-shaped and generally located betweenthe surface water channel and the legal roadboundary. It prevents water flowing onto the roador into its pavement layers.

SIDE SLOPE: that area of road formation, locatedbetween the SHOULDER HINGE POINT and thesurface water channel, having a gradient steeperthan 12:1.

SIDEWAY FORCE COEFFICIENT: see SFC.

SIEVE: a box or tray, the base of which is made ofwoven wire or similar material or perforated metalplate, with apertures of defined shapes and sizes,e.g. 13.2 mm, 9.5 mm, 6.7 mm, 4.75 mm, 2.36 mm.

SIGHT DISTANCE: the distance measured alongthe carriageway over which objects of definedheight are visible to a driver.


SIGNIFICANT HAZARD: an actual or potentialcause or source of serious harm, or harm whichdepends on the frequency or extent of exposureto the hazard, or harm which does not occur or isnot easily detectable until a significant time afterexposure.

SILT: a material intermediate in particle size betweensand and clay (i.e. 0.06–0.002 mm). Usually non-plastic.

SINGLE COAT CHIPSEAL: a single sprayedapplication of sealing binder followed immediatelywith a single application of chip which is spreadand rolled into place.

SINGLE-SIZED AGGREGATE/CHIP: an aggregateor chip in which the particle size distribution islimited to a very narrow range. See also GAP-GRADED and WELL-GRADED Aggregate/ Chip.

SKID RESISTANCE: the frictional resistanceprovided by the pavement surface to the vehicletyres during braking or cornering manoeuvres,which opposes skidding. It is usually measured onwet surfaces.

SLAKED LIME: calcium hydroxide, Ca(OH)2, alsoreferred to as Hydrated Lime, and supplied inpowdered form.

SLIP: a movement or fall of earth in a cut or bank.

SLOPE: the inclination of a surface with respect tothe horizontal expressed as rise or fall in a certainlongitudinal distance. Also an inclined surface.

SLP, STATIONARY LASER PROFILER: a machineused to measure Macrotexture (roughness) of apavement surface.

SLURRY SEAL: a surface dressing comprising aspecially graded aggregate mixed with an emulsionbinder, and a small percentage of cement and water.Not to be confused with MICROSURFACING whichhas a PME as binder.

SMA: see STONE MASTIC ASPHALT.

SOAK PIT: a large hole filled with rock or stone tocreate a large surface area in the surrounding groundso that surface run-off can soak away.

SOIL: unconsolidated inorganic and organicmaterial derived from weathering or breakdown ofrock and decay of organic material (from plants

and animals). The upper weathering layer abovebedrock.

SOUND LEVELS: pressure levels measured indecibels (dB) or adjusted decibels (dBA). See alsoDECIBEL.

SPAN:• The distance between the centres of adjacent

supports of a bridge, beam or truss.

• The superstructure of a bridge between twoadjacent supports.

SPECIALISED SURFACING: a surfacing designedto provide skid resistance (e.g. incorporatingCALCINED BAUXITE chip), to delineate uses of apavement (e.g. coloured bus lanes).

SPECIFICATION: a document containing bestpractice in construction and maintenance of roads,including specifications for materials, paving,surfacings, road formation, equipment, trafficcontrol, quality assurance. Most of the specificationsreferred to in this book are dated to indicate theversions that were used. Specifications referred toin contract and other works documents may notbe dated, to indicate that the latest version availableis to be used.

SPRAYBAR: a multiple DISTRIBUTOR for sprayingbinder. Also called Gangsprayer or Gangbar.

SPRAYING:• Application of bitumen on surface to be sealed.

• Use of chemicals and hot water to controlvegetation.

STABILISATION/ STABILISE: to modify any naturalmaterial to improve, correct a known deficiency,or maintain its load-carrying capacity, usually byadding lime, cement, emulsion, or water.

STABILISED MATERIAL: any material which hasbeen stabilised.

STABILITY (of asphalt): the ability to resistdeformation under load, without permanent lossof shape.

STANDARD AXLE LOAD: a single axle with dual-tyred wheels loaded to a total mass of 8.2 tonnes(80 kN).

STIFFNESS: the resistance of a material topermanent or recoverable deformation.


STOCKPILE: a heap or stack of material held instock for future use.

STOICHIOMETRIC AIR: the amount of air neededto provide enough oxygen atoms to match up witheach carbon and hydrogen atom in a fuel, so thatno oxygen, carbon or hydrogen is left over aftercombustion is complete.

STONE MASTIC ASPHALT (SMA): a gap-gradedhot mixed asphalt which has a high proportion ofcoarse aggregate that interlocks to form a stone-on-stone skeleton to resist permanent deformation.The stone skeleton is filled with a mastic of bitumenand filler to which fibres are added to provideadequate stability of the bitumen, and to preventdrainage of binder during transport to the site andplacement.

STRAIGHT-RUN BITUMEN: the residuum obtainedafter vacuum distillation of crude oil, not subjectedto further processing such as air-blowing or solventextraction.

STRAIN: the change of shape as a result of anapplied stress, expressed as a ratio of increase ordecrease divided by the original length. Elasticstrain is wholly recoverable.

STRATEGIC ROAD: a road which connects maincentres of population, and carries >2500 vpd.

STREET: a road within an urban locality.

STRESS: the force on a member divided by the areawhich carries the force, expressed in N/mm2 orMPa.

STRIPPING: see CHIP LOSS.• Displacement of binder from a chip surface by

action of water, e.g. in an asphaltic mix.

• Loss of chip from a chipseal, generally alongwheelpaths.

• The removal of formwork from concrete.

• The removal of the upper layer of soil or over-burden.

SUB-BASE: the material laid on the SUBGRADEbelow the BASECOURSE either for the purpose ofmaking up additional PAVEMENT thicknessrequired; to prevent intrusion of the subgrade intothe base; or to provide a working platform. Usuallyconstructed from aggregate, stabilised aggregate orstabilised soil, of larger size than material used inthe basecourse.

SUBGRADE: the trimmed or prepared portion ofthe formation (the ground) on which the pavementis constructed. Generally taken to relate to theupper line of the formation.

SUBSTRUCTURE: the piers and abutments(including wing walls) of a bridge which supportthe superstructure.

SUMP: see CATCH PIT.

SUPERELEVATION: the continuous transverse slopenormally given to the carriageway at horizontalcurves.

SUPERSTRUCTURE: the part of a bridge structurewhich is supported by the piers and abutments.

SURFACE COURSE: see SURFACING, WEARINGCOURSE.

SURFACE SEAL: a thin layer of bitumen and chipwhich prevents ingress of water into the pavement.

SURFACE WATER CHANNEL: an open drain orditch formed for the collection and drainage ofwater run-off from the road’s surface. The widthof the channel shall be a minimum of 1.0 m(0.5 m either side of the invert).

SURFACING: the uppermost part of a pavementspecifically designed to resist abrasion from trafficand to minimise the entry of water. It may bechipseal, asphaltic mix, or other material. SeeWEARING COURSE, TOP COURSE. Also calledSurface Course.

SWALE: an open vegetated drainage channel orshallow trough-like depression designed to carry,detain, partly treat and promote the filtration ofstormwater run-off, usually 5–10 m wide.

SWEEPING: the removal of loose material from apavement by means of a broom.

SWEEPINGS: material removed by sweeping,usually referring to chips.

TTACHOMETER: a counter that records thecumulative number of pump revolutions. They arefitted to DISTRIBUTORS.

TACK COAT: a thin application of binder toimprove adhesion between two seal layers, e.g.


between two layers of asphaltic mixes, or betweenan old chipseal and a new asphaltic mix layer.

TAMP: to COMPACT a loose material by repeatedblows.

TAR: a viscous product resulting from the destructivedistillation of carbonaceous material, coal beingthe most common source. (Tar, not to be confusedwith BITUMEN, is no longer used for roadmakingin New Zealand.)

TENSILE STRENGTH TEST: determination ofstrength and elasticity of a material when testedin tension under specified test conditions.

TEXTURE: irregularities in the pavement surfaceclassified in three groups by their dimensions:

TRAFFIC FLOW: the number of vehicles passinga given point during a specified period of time.

TRAFFIC ISLAND: a defined area, usually at anintersection, from which traffic is excluded andwhich is used for control of vehicular movementsand for pedestrian refuge.

TRAFFIC LANE: a portion of the paved carriagewayallotted for the use of a single line of vehicles.

TRAFFIC VOLUME: the number of vehicles flowingin both directions past a particular point in a giventime (e.g. vehicles per hour, vehicles per day (vpd)).See also TRAFFIC FLOW.

TRANSVERSE PROFILE: the shape of a pavementsurface measured as vertical distances from a datumperpendicular to traffic flow.

TREATMENT LENGTH: a uniformly performingsection of pavement, but different to sections oneither side of it. May be lengths of road scheduledfor resealing.

TRIAXIAL TEST: a test to determine the stress–strainproperties of a pavement material in which acylindrical specimen of the material is subjectedto a 3-dimensional stress system. The axial strainis related to the applied stress.

TRIMMING: finishing off the formation accuratelyto the designed profile.

TWO COAT CHIPSEAL: a chipseal with twoapplications of binder and two applications of chipapplied in the following sequence:• an application of sprayed binder followed

immediately with an application of large sizechip;

• a second application of sprayed binder, andanother application of finer chip.

Both coats are applied one after the other withlittle to no time delay between coats.

UULLAGE: the air space left when a container isnominally full; the unused part of the capacity ofa container. Ullage ensures that any subsequentexpansion of the liquid does not cause overflowor excessive hydraulic pressure. The ullage spaceis usually measured at 15°C.

Group Horizontal Vertical(mm) (mm)

Microtexture 0 – 0.5 0 – 0.2

Macrotexture 0.5 – 50 0.2 – 10

Megatexture 5 – 50 1 – 50

TEXTURISING SEAL: a pretreatment to prepare asurface for a reseal by reducing texture variance,or to reinstate texture. Also called PRETREATMENTSEAL.

TOE DRAIN: an interceptor drain constructed alongbottom of a batter to collect batter RUN-OFF.

TOE WALL: a low retaining wall constructed atthe foot of an earth slope.

TOP COURSE (or Top Surface): a pavement layerconstructed on top of the basecourse layer. Thislayer is constructed of material with a smaller topsize than the basecourse layer. See also SURFACING.

TOPPINGS: fine material from rock crushing,usually including dust, passing through a 4.75 mmsieve.

TRACKING: a term used in chipsealing for theblack discolouration in the WHEELPATHS causedby low viscosity binder being carried or tracked onvehicle tyres from its source (usually from on-roadBLEEDING).

TRAFFIC: a generic term covering any vehicles,persons or animals travelling on a road.


UNBOUND GRANULAR MATERIAL/BASE:aggregate or soil which contains no additives orbinder such as bitumen or cement. A base comprisedof granular or mechanically stabilised materials. Itcannot resist significant tensile stresses.

UNIFORMLY GRADED: an aggregate having alimited particle-size distribution approaching asingle size.

UNSEALED SHOULDER: that portion of thecarriageway, located between the edge of seal andthe shoulder hinge point, having a slope generallyno steeper than 12:1, except on curves where thesuperelevation may increase the slope.

UTILITIES SERVICES: services such as gas, water,electricity, telephone, sewer, and stormwater. Alsocalled Underground Services.

VVAPOUR VENTING: water vapour trapped in orbelow a seal rises and creates a bubble of binderrising to the pavement surface between the chip.When pricked the bubble, known as a VOLCANOhas a drop of water inside. The volcanoes tend tojoin up, ultimately resulting in a large area offlushed surface.

VEHICLE CLASS: classification of vehicles by type,or by number of axles. Vehicles may be:Passenger cars (LV); Light (LCV, up to 3.5t); Medium(MCV, over 3.5t); Heavy Commercial Vehicles (HCV-I with 3 or 4 axles; HCV-II with 5 or more axles);Buses. See Transfund NZ’s Project Evaluation Manual(2002) Appendix A2.2.1 for details, and LandTransport Rule (2002) Vehicle Dimensions and Massfor latest information.

VEHICLE TYPE: classification of vehicles by type,e.g. car, station wagon, utility, light commercialvehicle, etc., and/or by number of axles.

VERGE: the area of road located between theshoulder hinge point and the road boundary.

VERTICAL ALIGNMENT: the longitudinal profilealong the design line of a road.

VERTICAL CURVE: a curve in longitudinal profileof a carriageway to provide for gradual change ofgrade.

VIBRATING PLATE COMPACTOR: an automotivemachine which compacts by applying vibration tothe heavy metal plate on which it operates.

VIBRATING ROLLER: a roller that uses vibrationto assist compaction, characterised primarily byfrequency, amplitude and mass.

VISCOELASTICITY: the combined viscous andelastic response of a material to an applied stress.A viscoelastic material demonstrates both energystorage (elastic) and energy dissipation (viscous)responses to mechanical deformation.

VISCOMETER: an instrument for measuringviscosity. Bitumen viscosity is usually measuredusing capillary tube glass viscometers.

VISCOSITY:• The resistance of a fluid to flow, caused by

internal friction from inter-molecular cohesion.

• The numerical assessment of this property madeaccording to a prescribed method.

• The ratio of the shear stress to the rate of shearstrain of a Newtonian liquid.

A high viscosity liquid does not flow easily. Theviscosity of bitumen (or its cutbacks) is usuallymeasured by the time taken for a known volumeto flow by gravity through a calibrated capillarytube at a specified temperature. The result, kinematicviscosity, is expressed in mm2/s (or centistokes cSt).

v/l/d (Vehicles per Lane per Day): the volume oftraffic expressed as vehicles per lane per day.

vpd (Vehicles per Day): the number of vehiclesobserved passing a point on a road in bothdirections for 24 hours.

VOID: a space within a material, between particles,that is not occupied by solid matter. Voids may befilled with air (Air Voids), water or binder (bitumen).

VOID CONTENT: ratio of volume of voids to totalvolume of the material, expressed as %.

VOID RATIO: ratio of volume of voids to thevolume of solids in a material.

VOIDFILL SEAL: a seal for filling the voids in anexisting coarse textured chipseal surface. It is asingle very light application of binder, followed bya single application of fine chip designed to fit intothe texture of an existing chipseal surface.


VOLATILE SOLVENT: a low boiling pointhydrocarbon distillate used in the manufacture ofcutback bitumen to produce a binder with atemporarily low viscosity which will increase againas the solvent evaporates, e.g. white spirit.

VOLCANO: see VAPOUR VENTING.

WXYZWALK-OVER INSPECTION: a search for roaddefects carried out by inspecting the road at awalking pace.

WATER BLASTING: a HIGH PRESSURE WATERTREATMENT that uses a water pressure ofapproximately 15,000 psi at high volumes, muchgreater than used for WATER CUTTING.

WATER CONTENT: the quantity of water whichcan be removed from the aggregate or soil byheating at 105°C, until no further significant changein mass occurs. Usually expressed as a percentageof the dry weight. Sometimes called Moisture Content.

WATER CUTTING: a HIGH PRESSURE WATERTREATMENT that uses ultra-high pressure (up to36,000 psi) but low volumes of water. The pressureprovides the cutting action.

WATER TABLE: the natural level at which waterwould stand in an unpumped bore hole, well orother depression, under conditions of equilibrium.

WATERPROOFING: the process of renderingsurfaces or material impervious to water.

WATERWAY: a channel or stream; or an areaavailable for water to pass through or under astructure.

WEARING COURSE: the surface layer of apavement on which the traffic travels. It isspecifically designed for waterproofing, skid andabrasion resistance. See also SURFACING, may becalled TOP COURSE.

WEATHERING: the changes in rock resulting fromexposure to influences of the atmosphere.

WEATHERED: (generally of aggregates) partlydecomposed or otherwise affected by exposure toweather.

WELL GRADED: a chip having a particle-sizedistribution extending over a wide range of particle

sizes without excess or deficiency of any specificsizes within the range. See also SINGLE-SIZED andGAP-GRADED Aggregates/Chips.

WET LOCK SEAL: a seal coat applied to anotherseal with a light application of binder.

WETTING: the process of a liquid spreading overa solid, e.g. binder over chip.

WHEELPATH, also called Wheel track: the pathtaken by the wheels of a vehicle using a road.

WINDROW: the long ridge of material formed bya grader or earth-moving machine.

WORKABILITY: the ability of a material to bemanipulated, usually with reference to its placementand compaction.

ZONE: a portion of a study area, designated as suchfor particular land use and traffic analysis purposes.

glossary - nz transport agency · glossary see also list of abbreviations and acronyms on pp....

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