Definitions of highway terms

These definitions are helpful for those who are non-professional, particularly interpreters/translators. The technical terms are described in a easy-to-understand manner.

Ref. Terms Definitions
Abutments An abutment is an end support of a bridge superstructure.

Abutments are used for the following purposes:

  • to transmit the loads of from the superstructure to the foundations.
  • support the bearing devices.
  • support the backwalls


Construction aggregate, or simply “aggregate“, is a broad category of coarse particulate material used in construction, including sand, gravel, crushed stone, slag, recycled concrete and geosynthetic aggregates. Aggregates are a component of composite materials such as concrete and asphalt concrete; the aggregate serves as reinforcement to add strength to the overall composite material.

Road-making material utilizing uniformly sized stones rollered into layers and finished with asphalt. (Developed by the Scottish engineer John McAdam, 1756-1836.) (Prodic Dict.)

Annual average      daily traffic Annual average daily traffic, abbreviated AADT, is a measure used primarily in transportation planning and transportation engineering. It is the total volume of vehicle traffic of a highway or road for a year divided by 365 days. AADT is a useful and simple measurement of how busy the road is. It is also sometimes reported as “average annual daily traffic”.
arterial road An arterial road is a moderate or high-capacity road which is immediately below a highway level of service. Much like a biological artery, an arterial road carries large volumes of traffic between areas in urban centres. They are noted for their lack of residential entrances directly onto the road (except in older or denser communities); they are designed to carry traffic between neighbourhoods, and have intersections with collector and local streets. Often, commercial areas such as shopping centres, gas stations and other businesses are located on them. Arterial roads also link up to expressways and freeways with interchanges.
As-built drawing

shop drawing

Bản vẽ kỹ thuật thi công

working drawing

The phrase “as-built” in construction is equivalent to “as-is.” Drawings deemed “as-built” are thus drawings that show the EXISTING conditions as they are, or “as-is” — these are the actual existing conditions as opposed to designs or proposed conditions, which are more common for the content of drawings.

As-built drawings can be documented either after or during construction. When it’s after construction, a qualified technician collects accurate data to reconstruct the drawings. When it’s during construction, the design drawings are redmarked for editing.

For example, if you are a Contractor installing sewer pipe in the road at a buried depth of 5.00′ and you suddenly encounter an abandoned pipe and must change your buried depth to 6.50′ , then you should be responsible for the as-built conditions. The installing contractor should redmark his set of drawings to show how the sewer line was actually installed so that a draftsman can later edit the drawings into an “as-built” set.

A shop drawing is a drawing or set of drawings produced by the contractor, supplier, manufacturer, subcontractor, or fabricator.[1] Shop drawings are typically required for pre-fabricated components. Examples of these include: elevators, structural steel, trusses, pre-cast, windows, appliances, cabinets, air handling units, and millwork.

Shop drawings are not produced by architects and engineers under their contract with the owner. The shop drawing is the manufacturer’s or the contractor’s drawn version of information shown in the construction documents.[1] The shop drawing normally shows more detail than the construction documents. It is drawn to explain the fabrication and/or installation of the items to the manufacturer’s production crew or contractor’s installation crews. The style of the shop drawing is usually very different from that of the architect’s drawing. The shop drawing’s primary emphasis is on the particular product or installation and excludes notation concerning other products and installations, unless integration with the subject product is necessary.

A working drawing is a type of technical drawing, which is part of the documentation needed to build an engineering product or architecture. Typically in architecture these could include civil drawings, architectural drawings, structural drawings, mechanical drawings, electrical drawings, and plumbing drawings.

Asphalt concrete Asphalt concrete, normally known simply as asphalt or AC (in North America), is a composite material commonly used for construction of pavement, highways and parking lots. It consists of asphalt binder and mineral aggregate mixed together then laid down in layers and compacted.
Asphalt leveling course

Lớp bù vênh

A layer of an asphalt-aggregate mixture of variable thickness, used to eliminate irregularities in contour of an existing surface, prior to the placement of a superimposed layer.
At-grade intersection


Grade separation


Complete interchange

An at-grade intersection is a junction at which two or more transport axes cross at the same level (or grade).

An intersection is a road junction where two or more roads either meet or cross at grade (they are at the same level). Such a road junction may also be called a crossroads.

Grade separation is the process of aligning a junction of two or more transport axes at different heights (grades) so that they will not disrupt the traffic flow on other transit routes when they cross each other. The composition of such transport axes does not have to be uniform; it can consist of a mixture of roads, footpaths, railways, canals, or airport runways. Bridges, tunnels, or a combination of both can be built at a junction to achieve the needed grade separation.

In North America, a grade-separated junction may be referred to as a grade separation[1] or as an interchange – in contrast with an intersection or an at-grade, which are not grade-separated.

An interchange is a road junction that typically uses grade separation, and one or more ramps, to permit traffic on at least one road to pass through the junction without crossing any other traffic stream. It differs from an intersection, at which roads cross at grade. Interchanges are almost always used when at least one of the roads is a limited-access divided highway (expressway or freeway), though they may occasionally be used at junctions between two surface streets.

A complete interchange has enough ramps to provide access from any direction of any road in the junction to any direction of any other road in the junction.

average traffic speed The average speed of a traffic stream computed as the length of a highway segment divided by the average travel time of vehicles traversing the segment, in kilometres per hour.
backslope Where the roadway is in cut, the slope between the ditch and the natural ground away from the road is referred to as a backslope.
bill of quantities (BOQ) A bill of quantities (BOQ) is a document used in tendering in the construction industry in which materials, parts, and labor (and their costs) are itemized. It also (ideally) details the terms and conditions of the construction or repair contract and itemises all work to enable a contractor to price the work for which he or she is bidding.
borrow pit

Mỏ vật liệu

A borrow pit, also known as a sand box, is a term used in construction and civil engineering. It describes an area where material (usually soil, gravel or sand) has been dug for use at another location.[1] The term is literal — meaning a pit from where material was borrowed, although without an implication of someday returning the material.
Braking distance The distance travelled from the instant that braking begins to the instant the vehicle comes to a stop.
bypass A bypass is a road or highway that avoids or “bypasses” a built-up area, town, or village, to let through traffic flow without interference from local traffic, to reduce congestion in the built-up area, and to improve road safety.


cross slope

The cant of a road (sometimes referred to as camber or or railway (also referred to as superelevation) is the difference in elevation between the two edges. A non-zero cant gives a banked turn, allowing vehicles to traverse the turn at higher speeds than would otherwise be possible.
capacity utilization

(2-lane highway)

The ratio of the demand flow rate to the capacity of the facility.


Collector lane

Deceleration lane

Driving lane

Fire lane

Loading lane

Merge lane

passing lane

Through lane

Traffic lane

Transfer lane

Auxiliary lane

Express lane

Operational lane/ auxiliary lane

Overtaking lane

Emergency lane

Slow lane

A carriageway (Great Britain) or roadway (United States) is a group of two or more lanes on a single paved surface. A rural 2-lane highway is usually built on a single surface with traffic in both directions, while large highways can be built with two (sometimes more) of these separated by buffers such as medians and barriers. On such highways, the lanes in each group usually travel in the same direction

A collector lane of a road is used for slower moving traffic and has more access to exits/off ramps.

A deceleration lane is a paved or semi-paved lane adjacent to the primary road or street. It is used to improve traffic safety by allowing drivers to pull off the main road and decelerate safely in order to turn (e.g. right in the United States or left in Great Britain), so that the traffic behind the turning vehicle is not slowed or halted. Deceleration lanes are primarily found in suburban settings.

A driving lane is an area in a parking lot/car park in between parking spaces so that vehicles can drive into and out of the spaces.

A fire lane is the area next to a curb, which is reserved for firefighting equipment, ambulances, or other emergency vehicles. Parking in these areas, often marked by red lines, usually warrants a parking ticket.

A loading lane (loading zone in the United States) is an area next to a curb, which is reserved for loading and unloading passengers and/or freight. It may be marked by a sign (“LOADING ONLY” or “LOADING ZONE”) or by a yellow or white-painted curb.

A merge lane is a lane or onramp used to merge two flows of traffic into one, with the merge lane being the lane that disappears at the end of the merging area. Merge lane lengths depend mainly on the speed differential of the two merging flows, as the slower flow has to use the lane to accelerate.

A passing lane is often provided on steep mountain grades, in order to allow smaller vehicles to pass larger, slower ones. This is sometimes called a climbing lane if on the uphill side. (See truck lane below). Passing lanes may also be provided on long stretches of other roadway. On two-lane roads, using the lane of oncoming traffic as a passing lane is sometimes allowed given a long enough straightaway. In many countries permission is indicated by a broken line on the same side of the centerline as the vehicle intending to pass.

A through lane or thru lane is a traffic lane for through traffic. At intersections, these may be indicated by arrows on the pavement pointing straight ahead.

A traffic lane or travel lane is a lane for the movement of vehicles traveling from one destination to another, not including shoulders and auxiliary lanes.

A transfer lane of a road is used to move from express lanes to collector lanes, or vice-versa; it is somewhat similar to an auxiliary lane.

A lane placed in addition to and adjacent to a through lane, intended for aspecific manoeuvre such as turning, merging, diverging, weaving, and for slow vehicles, but not parking.

An auxiliary lane along a highway or motorway connects slip roads, with the entrance ramp or acceleration lane from one interchange leading to the exit ramp or deceleration lane of the next.

An express lane of a road is used for faster moving traffic and has less access to exits/off ramps. In other areas, an express lane may refer to a HOV lane (see below).

An operational lane or auxiliary lane is an extra lane on the entire length of highway between interchanges, giving drivers more time to merge in or out. The lane is created when an entrance ramp meets the highway, and drops out (with an “exit only” sign) to become the ramp at the next exit.[2]

An overtaking lane is the lane furthest from the shoulder of a multi-lane carriageway/roadway (sometimes called the fast lane, although this is deprecated by the authorities).

The emergency lane of a road (also known as the breakdown lane, shoulder or hard shoulder) is reserved for breakdowns, and for emergency vehicles. The inner boundary of the lane often features rumble strips in order to physically warn drowsy or inattentive drivers that they are drifting off the roadway. This feature is seen especially often on highways and motorways, where the minimally-stimulating and monotonous nature of high-speed driving at night increases the chances for driver disorientation and serious injury or death if an accident does take place.

The slow lane is the lane nearest to the shoulder of a multi-lane carriageway/roadway. This usage leads to the phrase Life in the Slow Lane, used as the title of various books and songs.

catch basin A catch basin (a.k.a., storm drain inlet, curb inlet) is an inlet to the storm drain system that typically includes a grate or curb inlet where stormwater enters the catch basin and a sump to capture sediment, debris and associated pollutants. They are also used in combined sewer watersheds to capture floatables and settle some solids. Catch basins act as pretreatment for other treatment practices by capturing large sediments. The performance of catch basins at removing sediment and other pollutants depends on the design of the catch basin (e.g., the size of the sump), and routine maintenance to retain the storage available in the sump to capture sediment.
Channelization The separation of traffic flow into positive paths, by means of traffic markings or islands.

Channelization is an engineering concept which employs the use of secondary roads to separate certain flows of traffic from the main traffic lanes. This method came into favor in the United States in the 1950s. (wiki)

collector road A collector road is a low or moderate-capacity road which is below a highway or arterial road functional class. Collector roads tend to lead traffic from local roads or sections of neighbourhoods to activity areas within communities, arterial roads or (occasionally) directly to expressways or freeways.
Concrete slump test Concrete slump test (or simply the slump test) is an in situ test or a laboratory test used to determine and measure how hard and consistent a given sample of concrete is before curing.

The concrete slump test is, in essence, a method of quality control.

cone penetration test (CPT)

standard penetration test (SPT)

triaxial shear test

The cone penetration test (CPT) is an in situ testing method used to determine the geotechnical engineering properties of soils and delineating soil stratigraphy. It was initially developed in the 1950s at the Dutch Laboratory for Soil Mechanics in Delft to investigate soft soils. Based on this history it has also been called the “Dutch cone test”. Today, the CPT is one of the most used and accepted in situ test methods for soil investigation worldwide.

The test method consists of pushing an instrumented cone tip first into the ground at a controlled rate (usually 2 centimeters/second). The resolution of the CPT in delineating stratigraphic layers is related to the size of the cone tip, with typical cone tips having a cross-sectional area of either 10 or 15 cm², corresponding to diameters of 3.6 and 4.4 cm.

The standard penetration test (SPT) is an in-situ dynamic penetration test designed to provide information on the geotechnical engineering properties of soil.

A triaxial shear test is a common method to measure the mechanical properties of many deformable solids, especially soil, sand, clay, and other granular materials or powders.

There are several variations on the basic concept of triaxial testing. These are given the following labels (corresponding test standard in parentheses):

  • CD — Consolidated drained
  • CU — Consolidated undrained (ASTM D4767)
  • UU — Unconsolidated undrained (ASTM D2850)
Congestion pricing/Congestion charges Congestion pricing or congestion charges is a system of surcharging users of a transport network in periods of peak demand to reduce traffic congestion.
crest vertical curve A vertical curve having a convex [kɔn’veks]  shape in profile.
Cross fall


The average grade between the edges of a cross-section element.
Cross-section The transverse profile of a road.
Crosswalk Any part of a roadway specifically intended for pedestrian crossing, and usually indicated by signs, lines or other markings.
Cul-de-sac A road open at one end only.
Curb or Kerb A curb or kerb (see spelling differences) is the edge where a raised pavement/sidewalk/footpath, road median, or road shoulder meets an unraised street or other roadway. Typically made from concrete, asphalt, or long stones (often granite), the purpose is twofold: first as a gutter for proper drainage of the roadway, and second for safety, to prevent motorists from driving onto the shoulder, median, sidewalk, or pavement
Datum line

Đường chuẩn

A fixed, measurable line, used as a reference from which angular or linear measurements are taken.
Deflection angle The angle between a roadway alignment line and the projection of the preceding line.
Design hour volume The number of vehicles that passes over a given section of a lane or a roadway during the 30th highest hourly volume of the design year.
Diamond interchange A four legged interchange with a single one-way ramp in each quadrant. All

left turns are made directly on the cross-road.



The proportion of traffic in each direction during the peak 15-minute flow period in the hour of interest.
Earthworks Earthworks are engineering works created through the moving of massive quantities of soil or unformed rock. Engineers need to concern themselves with issues of geotechnical engineering (such as soil fluidity and friction) and with quantity estimation to ensure that soil volumes in the cuts match those of the fills, while minimizing the distance of movement. In the past, these calculations were done by hand using a slide rule and with methods such as Simpson’s rule. Now they can be performed with a computer and specialized software, including optimisation on haul cost and not haul distance (as haul cost is not proportional to haul distance).
elevation The elevation of a geographic location is its height above a fixed reference point, often the mean sea level. Elevation, or geometric height, is mainly used when referring to points on the Earth‘s surface, while altitude or geopotential height is used for points above the surface, such as an aircraft in flight or a spacecraft in orbit


Cut and Fill

An embankment is therefore in some sense the opposite of a cutting, and embankments are often constructed using material obtained from a cutting. Alternatively the term fill is used to denote an embankment.

Embankments should be constructed using suitable materials to provide adequate support to the formation and long-term stability.

A cutting or cut is where part of a hill or mountain is cut out to make way for a road or rail line. It is in cut and fill construction used to keep the route straight and/or flat, where the comparative cost or practicality of alternate solutions (such as diversion) is too prohibitive. Contrary to the general meaning of cutting, a cutting in construction is mechanically excavated or blasted out with carefully-placed explosives. The cutting may only be on one side of a slope, or directly through the middle or top of a hill. Generally, a cutting is open at the top (otherwise it is a tunnel). A cutting is (in a sense) the opposite of an embankment.

Cut and Fill in earthmoving is the process of constructing a railway, road or canal whereby the amount of material from cuts roughly matches the amount of fill needed to make nearby embankments, so minimizing the amount of construction labor.

environmental impact assessment (EIA) An environmental impact assessment (EIA) is an assessment of the possible impact—positive or negative—that a proposed project may have on the environment; considering natural, social and economic aspects. The purpose of the assessment is to ensure that decision makers consider the ensuing environmental impacts to decide whether to proceed with the project.


An expressway is a divided highway for high-speed traffic with at least partial control of access. The degree of access allowed varies between countries and even between regions within the same country. In some jurisdictions, expressways are divided arterial roads with limits on the frequency of driveways and intersecting cross-streets. In other jurisdictions, access to expressways is limited only to grade-separated interchanges, making them the full equivalent of freeways.

The term expressway is currently used in Australia, Canada, China, Croatia, India, Iran, Japan, Kuwait, Malaysia, New Zealand, Nigeria, Pakistan, Philippines, Poland, Qatar, Singapore, South Korea, Taiwan, Thailand, and the United States (where the term originated).

A freeway is a type of road designed for safer high-speed operation of motor vehicles through the elimination of at-grade intersections. This is accomplished by preventing access to and from adjacent properties and eliminating all cross traffic through the use of grade separations and interchanges; railroad crossings are also removed. Such highways are usually divided with at least two lanes in each direction. Because traffic never crosses at-grade, there are generally no traffic lights or stop signs. Some countries have roads that function as freeways but use different names. These include autobahn, autovía, autoroute, autopista, autostrada, autosnelweg, motorway (in the UK and Ireland) and expressway in Asia.

In the United States, the term freeway is frequently used. In some regions of the U.S., other terms are also used, including Interstate, thruway, highway, expressway, and turnpike.

Fill sideslope Where the roadway is in fill, the slope between the roadway and the natural ground is referred to as the fill sideslope, or sometimes the fill slope.
Free-flow speed 1. The theoretical speed of traffic when density is zero; that is, there are no vehicles present; 2. the average speed of vehicles over an arterial segment not close to signalized intersections under conditions of low volume.
Friction factor The coefficient of friction between tire and roadway, measured either longitudinally or laterally.
frontage road A frontage road (also access road, feeder road, service drive, service road, outer road, and surface road, although the later term can also refer to other roadways that are not necessarily frontage roads) is a non-limited access road running parallel to a higher-speed road, usually a freeway, and feeding it at appropriate points of access (interchanges). In many cases, the frontage road is a former alignment of a road already in existence when the limited-access road was built. In other cases they may be built prior to construction of the limited-access road. In urban areas, frontage roads are frequently one-way roads when they exist on both sides of a highway. In more rural ones, such roads are typically two-way.
Geotextiles Geotextiles are permeable fabrics which, when used in association with soil, have the ability to separate, filter, reinforce, protect, or drain. Typically made from polypropylene or polyester, geotextile fabrics come in three basic forms: woven (looks like mail bag sacking).
Gore area Area between the edge of the highway and the ramp edge from the painted nose up to and including the gore. The painted nose is the intersection of the ramp inside lane edge with the highway outside lane edge.
Gradient (grade) The rate of rise or fall with respect to the horizontal distance; usually expressed as a percentage.
Hazard Any obstacle or other feature such as an embankment, or body of water of depth greater than 1m, that without protection, is likely to cause significant injury to the occupants of a vehicle encountering it. It may be natural or manmade.
headwall In civil engineering, a headwall is a small retaining wall placed at the outlet of a stormwater pipe or culvert.[1]
Horizontal alignment The configuration of a road or roadway as seen in plan, consisting of tangents, lengths of circular curve, and lengths of spiral or transition curves.


A divided highway in which each roadway is designed independently both in horizontal and vertical alignments, to take advantage of topographical features.
Kick-off Meeting

Wrap-up meeting

The Kick-off Meeting is the first meeting with the project team and the client of the project. This meeting would follow definition of the base elements for the project and other project planning activities. This meeting introduces the members of the project team and the client and provides the opportunity to discuss the role of each team member. Other base elements in the project that involve the client may also be discussed at this meeting (Schedule, Status Reporting, etc.).


A wrap-up meeting is designed to confirm that original purpose and scope of initiative were met. To this end, it is a prime opportunity to share the progress archieved thus far toward the original project’s goal, so the team can see the results of their efforts.

It also allow you to review the role, responsibilities and timeline outlined in the project turnover document with the larger project team.

Manhole A manhole (alternatively utility hole, maintenance hole or access chamber) is the top opening to an underground utility vault used to house an access point for making connections or performing maintenance on underground and buried public utility and other services including sewers, telephone, electricity, storm drains and gas.
Median On divided roads, including expressways, motorways, or autobahns, the central reservation (British English), median (North American English), median strip (North American English and Australian English) or central nature strip (Australian English) is the area which separates opposing lanes of traffic.
Median barrier A longitudinal barrier placed in the median to prevent a vehicle from crossing the median and colliding with oncoming traffic or to protect a vehicle from a fixed object in the median.
No passing zone A segment of a two-lane, two-way highway along which passing is prohibited in one or both directions.
Nondestructive testing (NDT) Nondestructive testing (NDT) is a wide group of analysis techniques used in science and industry to evaluate the properties of a material, component or system without causing damage.[1] Because NDT does not permanently alter the article being inspected, it is a highly-valuable technique that can save both money and time in product evaluation, troubleshooting, and research. Common NDT methods include ultrasonic, magnetic-particle, liquid penetrant, radiographic, and eddy-current testing.[1] NDT is a commonly-used tool in forensic engineering, mechanical engineering, electrical engineering, civil engineering, systems engineering, medicine, and art.
Non-recoverable slope A slope which is traversable but on which the errant vehicle will continue on to the bottom. Embankment slopes of between 4:1 and 3:1 are only considerate traversable but non-recoverable if they are smooth and have no fixed object hazards.
Observation wells Observation wells are engineered openings constructed through the solid earth, usually circular in cross-section, that are drilled or otherwise excavated to allow human access to specific zones of underground water for the purpose of measuring attributes such as water levels or pressure changes that would otherwise not be observable at the Earth’s surface.
Operating speed Operating speed is the highest overall speed at which a driver can travel on a given highway. This is under favourable weather conditions and under prevailing traffic conditions where the driver never exceeds the safe speed as determined by the design speed on a section-by-section basis
Overpass An overpass (called a flyover in the UK and most Commonwealth countries) is a bridge, road, railway or similar structure that crosses over another road or railway. An overpass structure is one that carries a higher capacity road above a lower capacity road, whereas a structure that permits a lower capacity road to travel above a larger capacity road is an underpass. Capacity is determined as either the number of lanes of travel provided or measured traffic count. In instances of actual or perceived equality between the traffic flows, the term structure can be used.
pedestrian overpass A pedestrian separation structure is any structure that removes pedestrians from a vehicle roadway. This creates a road junction where vehicles and pedestrians do not interact.

This can be considered a type of grade separation structure on the road.

Per diem Per diem is Latin for “per day” or “for each day”. It usually refers to the daily rate of any kind of payment. It may also refer to a specific amount of money that an organization allows an individual to spend per day, to cover living and traveling expenses in connection with work. It is the allowance given to the employee/worker for completing a task or going on tour away from home.
perimeter fence A perimeter fence is a structure that circles the perimeter of an area to prevent access. These fences are frequently made out of single vertical metal bars connected at the top and bottom with a horizontal bar. They often have spikes on the top to prevent climbing. (NH3)
Prime Coat

Tack Coat

(Asphalt) Seal Coat

The major purpose of prime coat is to protect the underlying layers from wet weather by providing a temporary waterproofing layer.

The purpose of tack coat is to ensure bond between the existing pavement surface and a new pavement surface.

An asphalt seal coat is a bituminous coating, with or without aggregate, applied to the surface of a pavement to waterproof and preserve the surface and to improve the texture of a previously applied bituminous surface.

raised pavement marker A raised pavement marker is a safety device used on roads. These devices are usually made with plastic, ceramic, or occasionally metal, and come in a variety of shapes and colours. Many varieties include a lens or sheeting that enhance their visibility by reflecting automotive headlights. Some other names for raised pavement markers include: Botts’ dots, delineators, cat’s eyes, road studs, or simply reflectors.
Ramp A highway ramp (as in exit ramp and entrance ramp) or slip road is a short section of road which allows vehicles to enter or exit a freeway (expressway).
Reinforced concrete

Prestressed concrete

Reinforced concrete is concrete in which steel reinforcement bars (“rebars“), plates or fibers have been incorporated to strengthen a material that would otherwise be brittle.

Prestressed concrete is a method for overcoming the concrete‘s natural weakness in tension. It can be used to produce beams, floors or bridges with a longer span than is practical with ordinary reinforced concrete. Prestressing tendons (generally of high tensile steel cable or rods) are used to provide a clamping load which produces a compressive stress that offsets the tensile stress that the concrete compression member would otherwise experience due to a bending load. Traditional reinforced concrete is based on the use of steel reinforcement bars, rebars, inside poured concrete.

Prestressing can be accomplished in three ways: pre-tensioned concrete, and bonded or unbonded post-tensioned concrete.

reverse curve a reverse curve is a section of the horizontal alignment of a route (highway or railroad) in which a curve to the left or right is followed immediately by a curve in the opposite direction.
Right of way The area of land acquired for or devoted to the provision of a road or highway.
Riprap Riprap — also known as rip rap (especially in Texas), rubble, shot rock or rock armour — is rock or other material used to armor shorelines, streambeds, bridge abutments, pilings and other shoreline structures against scour, water or ice erosion.

It is made from a variety of rock types, commonly granite, limestone or occasionally concrete rubble from building and paving demolition. It is used to protect coastlines and structures from erosion by the sea, rivers, or streams. It is used on any waterways or water containment where there is potential for water erosion.

Road slipperiness/ skid resistance Road slipperiness or skid resistance is the technical term for the cumulative effects of snow, ice, water, loose material and the road surface on the traction produced by the wheels of a vehicle.[1] Road slipperiness can be measured either in terms of the friction between a freely-spinning wheel and the ground, or the braking distance of a braking vehicle, and is related to the coefficient of friction between the tyre and the road surface.
Road surface marking Road surface marking is any kind of device or material that is used on a road surface in order to convey official information.

Road surface markings are used on paved roadways to provide guidance and information to drivers and pedestrians.

Road surface/ pavement Road surface (British English) or pavement (American English) is the durable surface material laid down on an area intended to sustain traffic (vehicular or foot traffic). Such surfaces are frequently marked to guide traffic. The most common modern paving methods are asphalt and concrete.
Roadside Station

Michi no eki

Rest area/

Travel plaza/

Rest stop/

Service area

A Roadside Station (道の駅, Michi no eki?) is a government-designated rest area found along roads and highways in Japan.

In addition to providing places for travelers to rest, they are also intended to promote local tourism and trade. You can often find shops selling local produce, snacks, souvenirs, and other goods.

As of March 1, 2007 there are 858 Roadside Stations across the country.

A rest area, travel plaza, rest stop, or service area is a public facility, located next to a large thoroughfare such as a highway, expressway, or freeway at which drivers and passengers can rest, eat, or refuel without exiting on to secondary roads. Other names include rest and service area (RSA), service station, resto, service plaza, and service center, service centre, and motorway services (or just “services” in the UK).

Roundabout Roundabout is a road junction at which traffic streams circularly around a central island.
Route assignment, route choice, or traffic assignment Route assignment, route choice, or traffic assignment concerns the selection of routes (alternative called paths) between origins and destinations in transportation networks. It is the fourth step in the conventional transportation forecasting model, following trip generation, trip distribution, and mode choice. The zonal interchange analysis of trip distribution provides origin-destination trip tables. Mode choice analysis tells which travelers will use which mode. To determine facility needs and costs and benefits, we need to know the number of travelers on each route and link of the network (a route is simply a chain of links between an origin and destination). We need to undertake traffic (or trip) assignment. Suppose there is a network of highways and transit systems and a proposed addition. We first want to know the present pattern of traffic delay and then what would happen if the addition were made.
Rumble strips Rumble strips (also known as audio tactile profiled markings) are a road safety feature that alert drivers to potential danger by causing a tactile vibration and audible rumbling, transmitted through the wheels into the car body.

A rumble strip is usually either applied in the direction of travel along an edge- or centerline, to alert drivers when they drift from their lane, or in a series of three or more across the direction of travel, to warn drivers of a stop ahead or nearby danger spot.

Sand blanket

Lớp đệm bằng cát

Signal timing Signal timing is the technique which traffic engineers use to determine who has the right-of-way at an intersection. Signal timing involves deciding how much green time the traffic lights shall provide at an intersection approach, how long the pedestrian WALK signal should be, and many numerous other factors.
Sod/ turf Sod or turf is grass and the part of the soil beneath it held together by the roots, or a piece of this material.

The term sod may be used to mean turf grown and cut specifically for the establishment of lawns.

Soil shear strength Soil shear strength can be computed based on the methods of application of load on the soil. The methods are classified as follows:

  1. Direct shear test
  2. Triaxial compressive test
  3. Vane shear test
  4. Unconfined compression test
Speed breaker/ speed bump

Speed cushions

A speed bump (in British English also speed hump, road hump or sleeping policeman; in New Zealand English a judder bar) is a velocity-reducing feature of road design to slow traffic or reduce through traffic. A speed bump is a bump in a roadway with heights typically ranging between 3 and 4 inches (7.6 and 10 cm). The length of speed bumps are typically less than or near to 1 foot (30 cm); whereas speed humps are longer and are typically 10 to 14 feet (3.0 to 4.3 m) in length.

Speed cushions are traffic calming devices designed as several small speed humps installed across the width of the road with spaces between them. They are generally installed in a series across a roadway resembling a split speed hump. The design of speed cushions forces cars to slow down as they ride with one or both wheels on the humps. However, the wider axle of emergency vehicles such as fire engines and ambulances allows them to straddle the cushions without slowing down or increasing response times. Although the newest available traffic calming device, speed cushions are rapidly growing in popularity due to their ability to slow cars without affecting emergency vehicles.

Superelevation Super elevation is tilting the roadway to help offset centripetal forces developed as the vehicle goes around a curve. Along with friction they are what keep a vehicle from going off the road.
Surface course

Base Course


Capping layer

Lớp đáy móng


Surface Course.  The layer in contact with traffic loads.  It provides characteristics such as friction, smoothness, noise control, rut resistance and drainage.  In addition, it prevents entrance of surface water into the underlying base, subbase and subgrade (NAPA, 2001).  This top structural layer of material is sometimes subdivided into two layers: the wearing course (top) and intermediate/binder course (bottom).

Gồm 2 lớp:

+ Wearing course: lớp mặt trên

+ Binder course: lớp mặt dưới

Base Course. The layer immediately beneath the surface course.  It provides additional load distribution and contributes to drainage and frost resistance.  Base courses are usually constructed out of aggregate or HMA (Hot mix asphalt).

Subbase Course.  The layer between the base course and subgrade.  It functions primarily as structural support but it can also (1) minimize the intrusion of fines from the subgrade into the pavement structure, (2) improve drainage and (3) minimize frost action damage.  The subbase generally consists of lower quality materials than the base course but better than the subgrade soils.  A subbase course is not always needed or used.

Subgrade is the native material underneath a constructed road,[1] pavement or railway (US: railroad) track. It is also called formation level.

The term can also refer to imported material that has been used to build an embankment

System interchange A freeway-to-freeway (or freeway-to-expressway) interchange, maintaining traffic on a controlled-access system.
Toe of slope The toe of the ravine or bluff slope is that point in the ravine or bluff where the slope is less than twenty-two (22) degrees or where the slope reverses directions. On compound slopes where there may be more than one possible toe location, the controlling point shall be whichever toe location provides the greater ravine or bluff area.
toll road

Toll booth

Toll plaza

Toll station

Toll gate

A toll road (or tollway, turnpike, pike, or toll highway) is a privately or publicly built road for which a driver pays a toll (a fee) for use. Structures for which tolls are charged include toll bridges and toll tunnels. Non-toll roads are financed using other sources of revenue, most typically fuel tax or general tax funds. The building or facility in which a toll is collected may be called a toll booth, toll plaza, toll station, or toll gate. This building is usually found on either side of a bridge and at exits.
traffic break A traffic break is any separation in the flow of traffic—naturally occurring or otherwise—along a road or highway. In heavily congested traffic, natural breaks occur rarely, thus the term traffic break most commonly refers to the manual separation of traffic, normally conducted by highway patrol officers.[1] In the UK, this manœuvre is known as a rolling roadblock.
Traffic calming Traffic calming is the slowing or reduction of motor-vehicle traffic to improve safety for pedestrians and bicyclists and improve the environment for residents. Urban planners and traffic engineers have many strategies for traffic calming.
traffic enforcement camera A traffic enforcement camera is a system, including a camera and a vehicle-monitoring device, used to detect and identify vehicles disobeying a speed limit or some other road legal requirement.
Transportation/ Traffic


Transportation forecasting is the process of estimating the number of vehicles or travelers that will use a specific transportation facility in the future. A forecast estimates, for instance, the number of vehicles on a planned freeway or bridge, the ridership on a railway line, the number of passengers patronizing an airport, or the number of ships calling on a seaport. Traffic forecasting begins with the collection of data on current traffic. Together with data on population, employment, trip rates, travel costs, etc., traffic data are used to develop a traffic demand model. Feeding data on future population, employment, etc. into the model results in output for future traffic, typically estimated for each segment of the transportation infrastructure in question, e.g., each roadway segment or each railway station.

Traffic forecasts are used for several key purposes in transportation policy, planning, and engineering: to calculate the capacity of infrastructure, e.g., how many lanes a bridge should have; to estimate the financial and social viability of projects, e.g., using cost-benefit analysis and social impact assessment; and to calculate environmental impacts, e.g., air pollution and noise.

Turnout A short section of a lane added to a two-lane, two-way highway for the purpose of allowing slow-moving vehicles to leave the main roadway and stop to allow faster vehicles to pass.

Tấm ngăn nước

A waterstop is an element of a concrete structure, intended to prevent the passages of fluids (such as water) when embedded in and running continuously through concrete joints. Waterstops are frequently manufactured from extruded plastics such as flexible polyvinyl chloride PVC, thermoplastic elastomeric rubber (TPE-R) or thermoplastic vulcanizate rubber (TPV); formed metal such as stainless steel, copper, or carbon steel; or extruded thermosets such as natural rubber, Styrene-butadiene rubber, or neoprene rubber.
Wingwall In a bridge, the wing walls are adjacent to the abutments and act as retaining walls. The wing walls can either be attached to the abutment or be independent of it.[1]

The soil and fill supporting the roadway and approach embankment are retained by the wing walls, which can be at a right angle to the abument or splayed at different angles. The wing walls are generally constructed at the same time and of the same materials as the abuments

Intelligent transportation system (ITS) Refers to efforts to add information and communications technology to transport infrastructure and vehicles in an effort to manage factors that typically are at odds with each other, such as vehicles, loads, and routes to improve safety and reduce vehicle wear, transportation times, and fuel consumption.
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