Highway engineering

Last updated
Highway engineering
Linn Cove Viaduct. This is the first precast concrete segmental concrete segmental viaduct to be built with the progressive method in the United States. It contains nearly HAER NC,11-ASHV.V,2-256 (CT).tif
The Blue Ridge Parkway atop the Appalachian Mountains of North Carolina, U.S.
Occupation
Names
  • Highway engineer
  • roadway engineer
  • street engineer
Synonyms
  • Roadway engineering
  • street engineering
Occupation type
 Profession
Activity sectors
Description
Competencies
Education required
Fields of
employment
Related jobs

Highway engineering (also known as roadway engineering and street engineering) is a professional engineering discipline branching from the civil engineering subdiscipline of transportation engineering that involves the planning, design, construction, operation, and maintenance of roads, highways, streets, bridges, and tunnels to ensure safe and effective transportation of people and goods. [1] [2] [3] Highway engineering became prominent towards the latter half of the 20th century after World War II. Standards of highway engineering are continuously being improved. Highway engineers must take into account future traffic flows, design of highway intersections/interchanges, geometric alignment and design, highway pavement materials and design, structural design of pavement thickness, and pavement maintenance. [1]

Contents

History

The beginning of road construction could be dated to the time of the Romans. [2] With the advancement of technology from carriages pulled by two horses to vehicles with power equivalent to 100 horses, road development had to follow suit. The construction of modern highways did not begin until the late 19th to early 20th century. [2]

The first research dedicated to highway engineering was initiated in the United Kingdom with the introduction of the Transport Research Laboratory (TRL), in 1930. [2] In the US, highway engineering became an important discipline with the passing of the Federal-Aid Highway Act of 1944, which aimed to connect 90% of cities with a population of 50,000 or more. [2] With constant stress from vehicles which grew larger as time passed, improvements to pavements were needed. With technology out of date, in 1958 the construction of the first motorway in Great Britain (the Preston bypass) played a major role in the development of new pavement technology. [2]

Planning and development

Highway planning involves the estimation of current and future traffic volumes on a road network. The Highway planning is also a basic need for the Highway development. Highway engineers strive to predict and analyze all possible civil impacts of highway systems. Some considerations are the adverse effects on the environment, such as noise pollution, air pollution, water pollution, and other ecological impacts. [3]

Financing

Developed countries are constantly faced with high maintenance cost of aging transportation highways. The growth of the motor vehicle industry and accompanying economic growth has generated a demand for safer, better performing, less congested highways. The growth of commerce, educational institutions, housing, and defense have largely drawn from government budgets in the past, making the financing of public highways a challenge. [4]

The multipurpose characteristics of highways, economic environment, and the advances in highway pricing technology are constantly changing. Therefore, the approaches to highway financing, management, and maintenance are constantly changing as well. [5]

Environmental impact assessment

The economic growth of a community is dependent upon highway development to enhance mobility. However, improperly planned, designed, constructed, and maintained highways can disrupt the social and economic characteristics of any size community. Common adverse impacts to highway development include damage of habitat and bio-diversity, creation of air and water pollution, noise and vibration generation, damage of natural landscape, and the destruction of a community's social and cultural structure. Highway infrastructure must be constructed and maintained to high qualities and standards. [6]

There are three key steps for integrating environmental considerations into the planning, scheduling, construction, and maintenance of highways. This process is known as an Environmental Impact Assessment, or EIA, as it systematically deals with the following elements: [6]

Highway safety

Highway systems generate the highest price in human injury and death, as nearly 50 million persons are injured in traffic accidents every year, not including the 1.2 million deaths. [7] Road traffic injury is the single leading cause of unintentional death in the first five decades of human life. [8]

Management of safety is a systematic process that strives to reduce the occurrence and severity of traffic accidents. The man/machine interaction with road traffic systems is unstable and poses a challenge to highway safety management. The key for increasing the safety of highway systems is to design, build, and maintain them to be far more tolerant of the average range of this man/machine interaction with highways. Technological advancements in highway engineering have improved the design, construction, and maintenance methods used over the years. These advancements have allowed for newer highway safety innovations. [8]

By ensuring that all situations and opportunities are identified, considered, and implemented as appropriate, they can be evaluated in every phase of highway planning, design, construction, maintenance, and operation to increase the safety of our highway systems. [3]

Design

The most appropriate location, alignment, and shape of a highway are selected during the design stage. Highway design involves the consideration of three major factors (human, vehicular, and roadway) and how these factors interact to provide a safe highway. Human factors include reaction time for braking and steering, visual acuity for traffic signs and signals, and car-following behaviour. Vehicle considerations include vehicle size and dynamics that are essential for determining lane width and maximum slopes, and for the selection of design vehicles. Highway engineers design road geometry to ensure stability of vehicles when negotiating curves and grades and to provide adequate sight distances for undertaking passing maneuvers along curves on two-lane, two-way roads. [3]

Geometric design

A typical cross-section drawing of a roadway Typical roadway cross-section sheet in transportation engineering.jpg
A typical cross-section drawing of a roadway

Highway and transportation engineers must meet many safety, service, and performance standards when designing highways for certain site topography. Highway geometric design primarily refers to the visible elements of the highways. Highway engineers who design the geometry of highways must also consider environmental and social effects of the design on the surrounding infrastructure. [9]

There are certain considerations that must be properly addressed in the design process to successfully fit a highway to a site's topography and maintain its safety. Some of these design considerations are: [9]

The operational performance of a highway can be seen through drivers' reactions to the design considerations and their interaction. [9]

Materials

The materials used for roadway construction have progressed with time, dating back to the early days of the Roman Empire. Advancements in methods with which these materials are characterized and applied to pavement structural design has accompanied this advancement in materials. [10]

There are three major types of pavement surfaces - pavement quality concrete (PQC), Portland cement concrete (PCC) and hot-mix asphalt (HMA). Underneath this wearing course are material layers that give structural support for the pavement system. These underlying surfaces may include either the aggregate base and sub base layers, or treated base and sub base layers, and additionally the underlying natural or treated sub grade. These treated layers may be cement-treated, asphalt-treated, or lime-treated for additional support. [10] New Material

Flexible pavement design

A flexible, or asphalt, or Tarmac pavement typically consists of three or four layers. For a four layer flexible pavement, there is a surface course, base course, and subbase course constructed over a compacted, natural soil subgrade. When building a three layer flexible pavement, the subbase layer is not used and the base course is placed directly on the natural subgrade. [11]

A flexible pavement's surface layer is constructed of hot-mix asphalt (HMA).Unstabilized aggregates are typically used for the base course; however, the base course could also be stabilized with asphalt, Foamed Bitumen,<Roadstone Recycling> Portland cement, or another stabilizing agent. The subbase is generally constructed from local aggregate material, while the top of the subgrade is often stabilized with cement or lime. [11]

With flexible pavement, the highest stress occurs at the surface and the stress decreases as the depth of the pavement increases. Therefore, the highest quality material needs to be used for the surface, while lower quality materials can be used as the depth of the pavement increases. The term "flexible" is used because of the asphalts ability to bend and deform slightly, then return to its original position as each traffic load is applied and removed. It is possible for these small deformations to become permanent, which can lead to rutting in the wheel path over an extended time. [11]

The service life of a flexible pavement is typically designed in the range of 20 to 30 years. [12] Required thicknesses of each layer of a flexible pavement vary widely depending on the materials used, magnitude, number of repetitions of traffic loads, environmental conditions, and the desired service life of the pavement. Factors such as these are taken into consideration during the design process so that the pavement will last for the designed life without excessive distresses. [11]

Rigid pavement design

Rigid pavements are generally used in constructing airports and major highways, such as those in the interstate highway system. In addition, they commonly serve as heavy-duty industrial floor slabs, port and harbor yard pavements, and heavy-vehicle park or terminal pavements. Like flexible pavements, rigid highway pavements are designed as all-weather, long-lasting structures to serve modern day high-speed traffic. Offering high quality riding surfaces for safe vehicular travel, they function as structural layers to distribute vehicular wheel loads in such a manner that the induced stresses transmitted to the subgrade soil are of acceptable magnitudes. [12]

Portland cement concrete (PCC) is the most common material used in the construction of rigid pavement slabs. The reason for its popularity is due to its availability and the economy. Rigid pavements must be designed to endure frequently repeated traffic loadings. The typical designed service life of a rigid pavement is between 30 and 40 years, lasting about twice as long as a flexible pavement. [12]

One major design consideration of rigid pavements is reducing fatigue failure due to the repeated stresses of traffic. Fatigue failure is common among major roads because a typical highway will experience millions of wheel passes throughout its service life. In addition to design criteria such as traffic loadings, tensile stresses due to thermal energy must also be taken into consideration. As pavement design has progressed, many highway engineers have noted that thermally induced stresses in rigid pavements can be just as intense as those imposed by wheel loadings. Due to the relatively low tensile strength of concrete, thermal stresses are extremely important to the design considerations of rigid pavements. [12]

Rigid pavements are generally constructed in three layers - a prepared subgrade, base or subbase, and a concrete slab. The concrete slab is constructed according to a designed choice of plan dimensions for the slab panels, directly influencing the intensity of thermal stresses occurring within the pavement. In addition to the slab panels, temperature reinforcements must be designed to control cracking behavior in the slab. Joint spacing is determined by the slab panel dimensions. [12]

Three main types of concrete pavements commonly used are jointed plain concrete pavement (JPCP), jointed reinforced concrete pavement (JRCP), and continuously reinforced concrete pavements (CRCP). JPCPs are constructed with contraction joints which direct the natural cracking of the pavement. These pavements do not use any reinforcing steel. JRCPs are constructed with both contraction joints and reinforcing steel to control the cracking of the pavement. High temperatures and moisture stresses within the pavement creates cracking, which the reinforcing steel holds tightly together. At transverse joints, dowel bars are typically placed to assist with transferring the load of the vehicle across the cracking. CRCPs solely rely on continuous reinforcing steel to hold the pavement's natural transverse cracks together. Prestressed concrete pavements have also been used in the construction of highways; however, they are not as common as the other three. Prestressed pavements allow for a thinner slab thickness by partly or wholly neutralizing thermally induced stresses or loadings. [12]

Flexible pavement overlay design

Over the service life of a flexible pavement, accumulated traffic loads may cause excessive rutting or cracking, inadequate ride quality, or an inadequate skid resistance. These problems can be avoided by adequately maintaining the pavement, but the solution usually has excessive maintenance costs, or the pavement may have an inadequate structural capacity for the projected traffic loads. [13]

Throughout a highway's life, its level of serviceability is closely monitored and maintained. One common method used to maintain a highway's level of serviceability is to place an overlay on the pavement's surface. [13]

There are three general types of overlay used on flexible pavements: asphalt-concrete overlay, Portland cement concrete overlay, and ultra-thin Portland cement concrete overlay. The concrete layer in a conventional PCC overlay is placed unbonded on top of the flexible surface. The typical thickness of an ultra-thin PCC overlay is 4 inches (10 cm) or less. [13]

There are two main categories of flexible pavement overlay design procedures: [13]

Rigid pavement overlay design

Near the end of a rigid pavement's service life, a decision must be made to either fully reconstruct the worn pavement, or construct an overlay layer. Considering an overlay can be constructed on a rigid pavement that has not reached the end of its service life, it is often more economically attractive to apply overlay layers more frequently. The required overlay thickness for a structurally sound rigid pavement is much smaller than for one that has reached the end of its service life. Rigid and flexible overlays are both used for rehabilitation of rigid pavements such as JPCP, JRCP, and CRCP. [14]

There are three subcategories of rigid pavement overlays that are organized depending on the bonding condition at the pavement overlay and existing slab interface. [14]

Drainage system design

Designing for proper drainage of highway systems is crucial to their success. A highway should be graded and built to remain "high and dry". [15] Regardless of how well other aspects of a road are designed and constructed, adequate drainage is mandatory for a road to survive its entire service life. Excess water in the highway structure can inevitably lead to premature failure, even if the failure is not catastrophic. [16]

Each highway drainage system is site-specific and can be very complex. Depending on the geography of the region, many methods for proper drainage may not be applicable. The highway engineer must determine which situations a particular design process should be applied, usually a combination of several appropriate methods and materials to direct water away from the structure. [16] Pavement subsurface drainage, and underdrains help provide extended life and excellent and reliable pavement performance. [17] Excessive moisture under a concrete pavement can cause pumping, cracking, and joint failure.

Erosion control is a crucial component in the design of highway drainage systems. Surface drainage must be allowed for precipitation to drain away from the structure. Highways must be designed with a slope or crown so that runoff water will be directed to the shoulder of the road, into a ditch, and away from the site. Designing a drainage system requires the prediction of runoff and infiltration, open channel analysis, and culvert design for directing surface water to an appropriate location. [16]

Construction, maintenance, and management

Highway construction

Highway construction is generally preceded by detailed surveys and subgrade preparation. [3] The methods and technology for constructing highways has evolved over time and become increasingly sophisticated. This advancement in technology has raised the level of skill sets required to manage highway construction projects. This skill varies from project to project, depending on factors such as the project's complexity and nature, the contrasts between new construction and reconstruction, and differences between urban region and rural region projects. [18]

There are a number of elements of highway construction which can be broken up into technical and commercial elements of the system. [18] Some examples of each are listed below:

Typically, construction begins at the lowest elevation of the site, regardless of the project type, and moves upward. By reviewing the geotechnical specifications of the project, information is given about: [18]

Subbase course construction

A subbase course is a layer designed of carefully selected materials that is located between the subgrade and base course of the pavement. The subbase thickness is generally in the range of 4 to 16 inches, and it is designed to withstand the required structural capacity of the pavement section. [18]

Common materials used for a highway subbase include gravel, crushed stone, or subgrade soil that is stabilized with cement, fly ash, or lime. Permeable subbase courses are becoming more prevalent because of their ability to drain infiltrating water from the surface. They also prevent subsurface water from reaching the pavement surface. [18]

When local material costs are excessively expensive or the material requirements to increase the structural bearing of the sub-base are not readily available, highway engineers can increase the bearing capacity of the underlying soil by mixing in Portland cement, foamed asphalt, or use polymer soil stabilization such as cross-linking styrene acrylic polymer that increases the California Bearing Ratio of in-situ materials by a factor 4 – 6. [19]

Base course construction

The base course is the region of the pavement section that is located directly under the surface course. If there is a subbase course, the base course is constructed directly about this layer. Otherwise, it is built directly on top of the subgrade. Typical base course thickness ranges from 4 to 6 inches and is governed by underlying layer properties. [18]

Heavy loads are continuously applied to pavement surfaces, and the base layer absorbs the majority of these stresses. Generally, the base course is constructed with an untreated crushed aggregate such as crushed stone, slag, or gravel. The base course material will have stability under the construction traffic and good drainage characteristics. [18]

The base course materials are often treated with cement, bitumen, calcium chloride, sodium chloride, fly ash, or lime. These treatments provide improved support for heavy loads, frost susceptibility, and serves as a moisture barrier between the base and surface layers. [18]

Surface course construction

There are two most commonly used types of pavement surfaces used in highway construction: hot-mix asphalt and Portland cement concrete. These pavement surface courses provide a smooth and safe riding surface, while simultaneously transferring the heavy traffic loads through the various base courses and into the underlying subgrade soils. [18]

Hot-mix asphalt layers

Hot-mix asphalt surface courses are referred to as flexible pavements. The Superpave System was developed in the late 1980s and has offered changes to the design approach, mix design, specifications, and quality testing of materials. [18]

The construction of an effective, long-lasting asphalt pavement requires an experienced construction crew, committed to their work quality and equipment control. [18]

Construction issues:

  • Asphalt mix segregation
  • Laydown
  • Compaction
  • Joints

A prime coat is a low viscosity asphalt that is applied to the base course prior to laying the HMA surface course. This coat bonds loose material, creating a cohesive layer between the base course and asphalt surface. [18]

A tack coat is a low viscosity asphalt emulsion that is used to create a bond between an existing pavement surface and new asphalt overlay. Tack coats are typically applied on adjacent pavements (curbs) to assist the bonding of the HMA and concrete. [18]

Portland cement concrete (PCC)

Portland cement concrete surface courses are referred to as rigid pavements, or concrete pavements. There are three general classifications of concrete pavements - jointed plain, jointed reinforced, and continuously reinforced. [18]

Traffic loadings are transferred between sections when larger aggregates in the PCC mix inter-lock together, or through load transfer devices in the transverse joints of the surface. Dowel bars are used as load-transferring devices to efficiently transfer loads across transverse joints while maintaining the joint's horizontal and vertical alignment. Tie-bars are deformed steel bars that are placed along longitudinal joints to hold adjacent pavement sections in place. [18]

Highway maintenance

A U.S. Federal Highway Administration (FHWA) worker inspects a washout in the shoulder of West Virginia Route 150. West Virginia State Route 150 shoulder washout.jpg
A U.S. Federal Highway Administration (FHWA) worker inspects a washout in the shoulder of West Virginia Route 150.

The overall purpose of highway maintenance is to fix defects and preserve the pavement's structure and serviceability. Defects must be defined, understood, and recorded in order to create an appropriate maintenance plan. Maintenance planning is solving an optimisation problem and it can be predictive. In predictive maintenance planning empirical, data-driven methods give more accurate results than mechanical models. [20] Defects differ between flexible and rigid pavements. [21]

There are four main objectives of highway maintenance:

Through routine maintenance practices, highway systems and all of their components can be maintained to their original, as-built condition. [21]

Project management

Project management involves the organization and structuring of project activities from inception to completion. Activities could be the construction of infrastructure such as highways and bridges or major and minor maintenance activities related to constructing such infrastructure. The entire project and involved activities must be handled in a professional manner and completed within deadlines and budget. In addition, minimizing social and environmental impacts is essential to successful project management. [22]

See also

Highway and parkway

Design and consideration

Related Research Articles

<span class="mw-page-title-main">Road</span> Land route

A road is a thoroughfare for the conveyance of traffic that mostly has an improved surface for use by vehicles and pedestrians. Unlike streets, whose primary function is to serve as public spaces, the main function of roads is transportation.

<span class="mw-page-title-main">Road transport</span> Collective term for all forms of transport which takes place on roads

Road transport or road transportation is a type of transport using roads. Transport on roads can be roughly grouped into the transportation of goods and transportation of people. In many countries licensing requirements and safety regulations ensure a separation of the two industries. Movement along roads may be by bike, automobile, bus, truck, or by animal such as horse or oxen. Standard networks of roads were adopted by Romans, Persians, Aztec, and other early empires, and may be regarded as a feature of empires. Cargo may be transported by trucking companies, while passengers may be transported via mass transit. Commonly defined features of modern roads include defined lanes and signage. Various classes of road exist, from two-lane local roads with at-grade intersections to controlled-access highways with all cross traffic grade-separated.

The Shell pavement design method was used in many countries for the design of new pavements made of asphalt. First published in 1963, it was the first mechanistic design method, providing a procedure that was no longer based on codification of historic experience but instead that permitted computation of strain levels at key positions in the pavement. By analyzing different proposed constructions, the procedure allowed a designer to keep the tensile strain at the bottom of the asphalt at a level less than a critical value and to keep the vertical strain at the top of the subgrade less than another critical value. With these two strains kept, respectively, within the design limits, premature fatigue failure in the asphalt and rutting of the pavement would be precluded. Relationships linking strain values to fatigue and rutting permitted a user to design a pavement able to carry almost any desired number of transits of standard wheel loads.

<span class="mw-page-title-main">Road surface</span> Road covered with durable surface material

A road surface or pavement is the durable surface material laid down on an area intended to sustain vehicular or foot traffic, such as a road or walkway. In the past, gravel road surfaces, macadam, hoggin, cobblestone and granite setts were extensively used, but these have mostly been replaced by asphalt or concrete laid on a compacted base course. Asphalt mixtures have been used in pavement construction since the beginning of the 20th century and are of two types: metalled (hard-surfaced) and unmetalled roads. Metalled roadways are made to sustain vehicular load and so are usually made on frequently used roads. Unmetalled roads, also known as gravel roads or dirt roads, are rough and can sustain less weight. Road surfaces are frequently marked to guide traffic.

<span class="mw-page-title-main">Asphalt concrete</span> Composite material used for paving

Asphalt concrete is a composite material commonly used to surface roads, parking lots, airports, and the core of embankment dams. Asphalt mixtures have been used in pavement construction since the beginning of the twentieth century. It consists of mineral aggregate bound together with bitumen, laid in layers, and compacted.

<span class="mw-page-title-main">Subgrade</span> Material underneath a road or track

In transport engineering, subgrade is the native material underneath a constructed road, pavement or railway track. It is also called formation level.

<span class="mw-page-title-main">Permeable paving</span> Roads built with water-pervious materials

Permeable paving surfaces are made of either a porous material that enables stormwater to flow through it or nonporous blocks spaced so that water can flow between the gaps. Permeable paving can also include a variety of surfacing techniques for roads, parking lots, and pedestrian walkways. Permeable pavement surfaces may be composed of; pervious concrete, porous asphalt, paving stones, or interlocking pavers. Unlike traditional impervious paving materials such as concrete and asphalt, permeable paving systems allow stormwater to percolate and infiltrate through the pavement and into the aggregate layers and/or soil below. In addition to reducing surface runoff, permeable paving systems can trap suspended solids, thereby filtering pollutants from stormwater.

<span class="mw-page-title-main">Base course</span>

The base course or basecourse in pavements is a layer of material in an asphalt roadway, race track, riding arena, or sporting field. It is located under the surface layer consisting of the wearing course and sometimes an extra binder course.

<span class="mw-page-title-main">Falling weight deflectometer</span> Road testing device

A falling weight deflectometer (FWD) is a testing device used by civil engineers to evaluate the physical properties of pavement in highways, local roads, airport pavements, harbor areas, railway tracks and elsewhere. The data acquired from FWDs is primarily used to estimate pavement structural capacity, to facilitate overlay design or determine if a pavement is being overloaded. Depending on its design, a FWD may be contained within a towable trailer or it may be built into a self-propelled vehicle such as a truck or van. Comprehensive road survey vehicles typically consist of a FWD mounted on a heavy truck together with a ground-penetrating radar and impact attenuator.

Soil cement is a construction material, a mix of pulverized natural soil with small amount of portland cement and water, usually processed in a tumbler, compacted to high density. Hard, semi-rigid durable material is formed by hydration of the cement particles.

<span class="mw-page-title-main">Subbase (pavement)</span> Layer of a paved road

In highway engineering, subbase is the layer of aggregate material laid on the subgrade, on which the base course layer is located. It may be omitted when there will be only foot traffic on the pavement, but it is necessary for surfaces used by vehicles.

<span class="mw-page-title-main">Gravel road</span> Type of unpaved road surfaced with gravel

A gravel road is a type of unpaved road surfaced with gravel that has been brought to the site from a quarry or stream bed. Gravel roads are common in less-developed nations, and also in the rural areas of developed nations such as Canada and the United States. In New Zealand, and other Commonwealth countries, they may be known as metal roads. They may be referred to as "dirt roads" in common speech, but that term is used more for unimproved roads with no surface material added. If well constructed and maintained, a gravel road is an all-weather road.

<span class="mw-page-title-main">Pavement engineering</span>

Pavement engineering is a branch of civil engineering that uses engineering techniques to design and maintain flexible (asphalt) and rigid (concrete) pavements. This includes streets and highways and involves knowledge of soils, hydraulics, and material properties. Pavement engineering involves new construction as well as rehabilitation and maintenance of existing pavements.

<span class="mw-page-title-main">Paver (vehicle)</span> Construction equipment used to lay asphalt

A paver is a piece of construction equipment used to lay asphalt concrete or Portland cement concrete on roads, bridges, parking lots and other such places. It lays the material flat and provides minor compaction. This is typically followed by final compaction by a road roller.

<span class="mw-page-title-main">Cellular confinement</span> Confinement system used in construction and geotechnical engineering

Cellular confinement systems (CCS)—also known as geocells—are widely used in construction for erosion control, soil stabilization on flat ground and steep slopes, channel protection, and structural reinforcement for load support and earth retention. Typical cellular confinement systems are geosynthetics made with ultrasonically welded high-density polyethylene (HDPE) strips or novel polymeric alloy (NPA)—and expanded on-site to form a honeycomb-like structure—and filled with sand, soil, rock, gravel or concrete.

<span class="mw-page-title-main">Crocodile cracking</span> Distress in asphalt pavement

Crocodile cracking is a common type of distress in asphalt pavement. The following is more closely related to fatigue cracking which is characterized by interconnecting or interlaced cracking in the asphalt layer resembling the hide of a crocodile. Cell sizes can vary in size up to 300 millimetres (12 in) across, but are typically less than 150 millimetres (5.9 in) across. Fatigue cracking is generally a loading failure, but numerous factors can contribute to it. It is often a sign of sub-base failure, poor drainage, or repeated over-loadings. It is important to prevent fatigue cracking, and repair as soon as possible, as advanced cases can be very costly to repair and can lead to formation of potholes or premature pavement failure.

Diamond grinding is a pavement preservation technique that corrects a variety of surface imperfections on both concrete and asphalt concrete pavements. Most often utilized on concrete pavement, diamond grinding is typically performed in conjunction with other concrete pavement preservation (CPP) techniques such as road slab stabilization, full- and partial-depth repair, dowel bar retrofit, cross stitching longitudinal cracks or joints and joint and crack resealing. Diamond grinding restores rideability by removing surface irregularities caused during construction or through repeated traffic loading over time. The immediate effect of diamond grinding is a significant improvement in the smoothness of a pavement. Another important effect of diamond grinding is the considerable increase in surface macrotexture and consequent improvement in skid resistance, noise reduction and safety.

<span class="mw-page-title-main">Paver base</span>

Paver base is a form of aggregate used in the construction of patios and walkways whose topmost layer consists of mortarless pavers. The first layer in the construction of such a surface is called the subgrade—this is the layer of native material underneath the intended surface. It is usually compacted and stabilized. If the final pavement is to have vehicle traffic, a layer of subbase of crushed stone or concrete must come next—this layer will even out the subgrade and will bear the heaviest load from the pavement above. Next comes the base course composed of crushed gravel varying from 0.75 in (1.9 cm) down to dust-particle size. It too is typically compacted and evened. The next layer will be the paver base, composed of coarse sand and typically between 6 and 12 in thick, depending on anticipated traffic.

The wearing course, also known as a friction course or surface course, is the upper layer in roadway, airfield, and dockyard construction. The term 'surface course' is sometimes used slightly different, to describe very thin surface layers such as chip seal. In rigid pavements the upper layer is a portland cement concrete slab. In flexible pavements, the upper layer consists of asphalt concrete, that is a construction aggregate with a bituminous binder. The wearing course is typically placed on the binder course which is then laid on the base course, which is normally placed on the subbase, which rests on the subgrade. There are various different types of flexible pavement wearing course, suitable for different situations.

The Neoloy Geocell is a Cellular Confinement System (geocell) developed and manufactured by PRS Geo-Technologies Ltd. Geocells are extruded in ultrasonically welded strips. The folded strips are opened on-site to form a 3D honeycomb matrix, which is then filled with granular material. The 3D confinement system is used to stabilize soft subgrade soil and reinforce the subbase and base layers in flexible pavements. Cellular confinement is also used for soil protection and erosion control for slopes, including channels, retention walls, reservoirs and landfills.

References

  1. 1 2 Rogers, Martin (2002). Highway engineering. Oxford, UK: Blackwell Science. ISBN   978-0-632-05993-5.
  2. 1 2 3 4 5 6 O'Flaherty, C.A., ed. (2002). Highways the location, design, construction and maintenance of road pavements (4th ed.). Oxford: Butterworth-Heinemann. ISBN   978-0-7506-5090-8.
  3. 1 2 3 4 5 "Highway engineering." McGraw-Hill Concise Encyclopedia of Science and Technology. New York: McGraw-Hill, 2006. Credo Reference. Web. 13 February 2013.
  4. ↑ Chin, Antony T.H. "Financing Highways." The Handbook of Highway Engineering. Ed. T.W. Fwa. CRC Press, 2005.
  5. ↑ Estache, A., Romero, M., and Strong, J. 2000. The Long and Winding Path to Private Financing and Regulation of Toll Roads. The World Bank, Washington, DC, 49 pp.
  6. 1 2 3 4 5 Aziz, M.A. "Environmental Impact Assessment of Highway Development." The Handbook of Highway Engineering. Ed. T.W. Fwa. CRC Press, 2005.
  7. ↑ World Health Organization, 2004. World Report on Road Traffic Injury Prevention. World Health Organization, Geneva.
  8. 1 2 Johnston, Ian. "Highway Safety." The Handbook of Highway Engineering. Ed. T.W. Fwa. CRC Press, 2005.
  9. 1 2 3 Cheu, R.L. "Highway Geometric Design." The Handbook of Highway Engineering. Ed. T.W. Fwa. CRC Press, 2005.
  10. 1 2 Tam, Weng On. "Highway Materials." The Handbook of Highway Engineering. Ed. T.W. Fwa. CRC Press, 2005.
  11. 1 2 3 4 Mamlouk, Michael S. "Design of Flexible Pavements." The Handbook of Highway Engineering. Ed. T.W. Fwa. CRC Press, 2005.
  12. 1 2 3 4 5 6 Fwa, T.F. and Wei, Liu. "Design of Rigid Pavements." The Handbook of Highway Engineering. Ed. T.W. Fwa. CRC Press, 2005.
  13. 1 2 3 4 Tia, Mang. "Overlay Design for Flexible Pavements." The Handbook of Highway Engineering. Ed. T.W. Fwa. CRC Press, 2005.
  14. 1 2 Fwa, T.F. "Overlay Design for Rigid Pavements." The Handbook of Highway Engineering. Ed. T.W. Fwa. CRC Press, 2005.
  15. ↑ Archived 2020-10-19 at the Wayback Machine Minnesota | Dept. of Transportation| Pavement Manual | 5-4.02 Subsurface Drainage
  16. 1 2 3 Ksaibati, Khaled and Kolkman, Laycee L. "Highway Drainage Systems and Design." The Handbook of Highway Engineering. Ed. T.W. Fwa. CRC Press, 2005.
  17. ↑ Design, Construction and Maintenance of Concrete Pavements at the | World's Busiest Airport | W. Charles Greer, Jr., P.E. | AMEC Environment & Infrastructure, Inc., Alpharetta, GA, USA | Subash Reddy Kuchikulla | Materials Managers and Engineers, Inc., Atlanta, GA, USA | Kathryn Masters, P.E. | Hartsfield | Jackson Atlanta International Airport, Atlanta, GA, USA | John Rone, P.E. | Hartsfield | Jackson Atlanta International Airport, Atlanta, GA
  18. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Gunalan, K.N. "Highway Construction." The Handbook of Highway Engineering. Ed. T.W. Fwa. CRC Press, 2005.
  19. ↑ "AggreBind - Soil Stabilized Roads and Highways".
  20. ↑ Sirvio, Konsta (2017) Advances in predictive maintenance planning of roads by empirical models. Aalto University publication series DOCTORAL DISSERTATIONS, 166/2017. (https://www.researchgate.net/publication/319998419_Advances_in_predictive_maintenance_planning_of_roads_by_empirical_models Archived 2017-11-15 at the Wayback Machine )
  21. 1 2 Van Wijk, Ian. "Highway Maintenance." The Handbook of Highway Engineering. Ed. T.W. Fwa. CRC Press, 2005.
  22. ↑ Walker, Derek and Kumar, Arun. "Project Management in Highway Construction." The Handbook of Highway Engineering. Ed. T.W. Fwa. CRC Press, 2005.

External links: highway design standards

Further reading

This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.