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Sound waves in the process of transmission, sound barriers encountered, reflection, transmission and diffraction occurs three phenomenon. Usually we think barrier to prevent the spread of direct sound, and makes the transmission attenuation, sound enough and the influence of sound transmission can be neglected. Therefore, sound insulation effect of the noise barrier generally can use amount of noise reduction, said it reflects both shielding acoustic noise barrier ability. Inserts a noise barrier between the source and receiver, a barrier to infinite, sound waves can only from diffraction above barrier in the past, and form a sound shadow, after that just like the light is blocked by the object and forms a shadow. In the acoustic shadow area, people can feel noise obviously decreases, this is the noise reduction effect of the noise barrier.

Classification structure classification of noise barrier

According to the application of environmental noise barrier, divided into traffic noise barriers and noise barrier equipment noise attenuation of noise barriers, industrial factory boundary noise barriers.

According to the material classification and noise barrier can be divided into the following categories: metal sound barriers (metal shutter), metal mesh hole, concrete noise barrier (lightweight concrete, high strength concrete), PC sound barriers, FRP acoustic barrier, etc. Organic glass plate has the most wide and 2.7 meters wide PC toughened in wuxi are into the production, sound barriers factory installation is successful, greatly improve the visual and noise reduction effect

According to the different purposes and can be divided into several categories: railway, highway noise barrier, urban noise barrier, residential area landscape sound barrier drop noise barrier, etc.

Sound barrier structure

Outdoor noise barrier generally use brick or concrete structures, indoor sound barrier, citing steel, wood, PMMA/POLYCARBONATE SHEET plastic pull, gypsum board and aluminum foam structure. Noise barrier is mainly composed of steel columns and acoustic screen plate in two parts, absorption column is the main stress components of noise barrier, it is fixed by bolts or welding at the edge of the road against a wall or rail on the embedded steel plate; Sucking sound insulation board is the main acoustic absorption component, it by high strength spring clamp should be fixed to the H column groove, form the sound barrier. Sound barrier design has been relatively fully considering the elevated expressways, urban light rail, subway of wind load, the transportation vehicle crash safety and all-weather outdoor anticorrosive problem. Production of refined its appearance is beautiful and easy, convenient transportation and installation, low cost, long service life, especially suitable for elevated expressways and urban light rail, subway anti noise use, is a modern city the ideal sound insulation noise reduction facilities.

Sound barriers between 1 m A 5 m height, cover area effective noise reduction for an average of 10 ~ 15 db (A) (125 hz ~ 40000 hz, 1/3 octave), up to 20 db (A). In general, the higher the sound barrier, or the farther away from the noise barrier, the noise reduction result is better.

Series is introduced

Crown fly aluminum noise barrier fiber cotton series

Aluminum noise barrier fiber cotton specification: 30 mm thick

Noise reduction coefficient of the NRC = 0.85

Crown sound-absorbing noise barrier rock wool series

Rock wool noise barrier performance characteristics

1, the adiabatic performance: good heat insulation performance is the basic characteristic of the rock wool products, under the condition of normal temperature (25 ℃ or so) rock wool thermal conductivity is usually between 0.03 ~ 0.047 W/(moK).

2, combustion performance: rock wool, mineral wool products of combustion performance depends on the amount of combustible dope. Rock wool itself belongs to the inorganic mineral fibre, nonflammable, in the process of processing into products, and sometimes to add organic binder or additives, the combustion performance of products can produce certain effect.

3, sound insulation performance: rock wool products with excellent sound insulation and sound absorption performance, the sound absorption mechanism is this kind of products with porous structure, when the sound waves through the friction due to the effect of flow resistance, make part of the sound energy is absorbed by the fiber, Yin in the acoustic transmission.

Crown flying rock wool noise barrier application:

Since the 1970 s, the rock wool is widely used in construction and industrial equipment, pipelines, kiln of adiabatic, fire prevention, acoustic, seismic, metallurgy, machinery, building materials, petroleum, chemical and other industries.

The main technical performance index of rock wool products

Cement sound-absorbing

High strength cement lightweight composite acoustic noise barriers: light weight, high strength cement XiGeYin plate adopts advanced technology and raw materials to produce products of the efficient absorption of noise reduction, technical performance in the domestic advanced level. Various types of structure, beautiful appearance. Can meet the design requirements of different, widely used in highway, railway, bridge and noise at boundary of industrial management engineering.

Aluminum absorption

Pinhole composite sound absorption characteristics of aluminum plate products: light non-polluting, anti-glare, anti-aging, impact resistance and freeze resistance, sound absorption coefficient of stability, resistance to wet, easy to corrupt, easy to bend processing, easy to transport, disassembling maintenance convenience, price reasonable, and can spray all sorts of color.

Pinhole compound aluminum plate technical parameters:

1, the noise reduction coefficient: 75 mm cavity when the NRC acuity 0.70;

2, sound insulation quantity: 30 db (A) or higher;

3, artificial accelerated weathering (250 h) : no pulverization;

4, salt fog corrosion resistance: acidic 1000 h, appearance rating level 10, no pitting, blister, spalling corrosion phenomenon;

5, tensile load, p 1305 n;

A grade 6, fire rating: otherwise

Rock plate acoustical

Perlite is a kind of pores, inorganic cement composite material, it contains no pollutants, basic is the cement, natural minerals and other chemical materials via special processing, after mixing, molding forming, so durable, and the plasticity is very high, can be prepared into different density, shape, color and appearance to adapt to the different conditions of installation and design, to meet the need of practical application. Compared with other existing acoustic insulation materials, perlite material has the following features:

Perlite has the stable, sound absorption performance of the noise barrier around NRC0.85 noise reduction coefficient, high frequency section in noise sound-absorbing performance is good, comply with the requirement of road noise barrier acoustics.

Application and installation is simple and can be prefabricated or forming at the scene.

Ingredients: no organic ingredients and contains no pollution, for example, asbestos, mineral fiber, polystyrene, cellulose, not bibulous, wind and rain erosion resistant, easy cleaning, can be exposed in the outdoor environment, strong durability, resistance to natural aging.

Low density, high temperature resistant, low temperature, acid, alkali corrosion and fire protection.

Coefficient of acoustic absorption audio bandwidth, noise reduction NRC0.85 around 46 db sound insulation quantity.

Soft color, color multiple-choice, beautiful and easy, European style.

Orifice absorption

The principle of microperforated panel is on board a certain number of holes, plate after leaving the air layer, the incoming sound waves to produce resonance absorption, so as to achieve the effect of sound absorption. Sound barriers of microperforated panel has been widely applied in the place such as highways, urban overhead. Material from the earliest of microperforated panel PC board, acrylic board, development to choi steel, aluminum and other metal materials.

The advantage of micro perforation plate is:

High temperature resistance, resistance to moisture, air impact at a high speed.

Has the stable, sound absorption performance of the average sound absorption coefficient is greater than 0.60, the noise reduction coefficient NRC0.60, comply with the requirement of road noise barrier acoustics.

Sawdust absorption

Cement by sawdust sawdust composite acoustic absorption board, cement and chemical additives made through a series of special process, it has excellent sound absorption performance, high strength, corrosion resistance and long service life and can satisfy the requirement of design and application of different, can form a variety of structural form, is the traffic noise, industry noise, residential park noise ideal material.

PC board

A sound barriers, special on the mechanical properties of the PC board

1, the impact strength: PC endurance plate excellent shock resistance, it is 250 times higher than the traditional glass, 30 times higher than acrylic. The impact strength of Pc endurance plate is a "transparent plate," said.

2, good tensile strength, PC endurance plate heat resistance, even at 120 ℃, its tensile strength is still up to 350 KGF/cm2.

3, bending strength, excellent PC endurance plate bending, even if the bending Angle of 90 °, is still not broken.

4, fatigue and creep resistance: PC endurance plate creep resistance is one of the best in the thermoplastic plastic. Even if its creep at high temperature is still very small.

Second, the sound barrier special PC board thermal performance

1, melting temperature: PC endurance plate melt temperature 135 ℃, the temperature of 120 ℃ continuous use.

2, linear expansion coefficient, linear expansion coefficient of 7 x 10-5 cm/cm / ℃ is smaller in the plastic.

3, brittle temperature: PC endurance plate brittle temperature was minus 40 ℃, the minimum temperature for continuous use - 30 ℃, is than the general plastic.

4, combustibility: PC endurance plate belongs to one of flame retardant self-extinguishing plastics, it does not produce poisonous gas in high temperature heating.

5, thermal conductivity: PC endurance plate thermal conductivity and the general plastic difference is not big, is about a quarter of the glass, 1/300 of the iron, aluminum, 1/1000 of 1/2000 of the copper, is one of the good performance of heat preservation material.

Three sound barriers, special optical properties of the PC board

1, light transmittance: PC endurance plate between the light transmittance of 85% to 90% with the glass.

2, weather resistance: general PC sheet endurance long exposure outside, easy cause yellowing by ultraviolet radiation and surface degradation. Irreverent comedy PC endurance plate surface with a layer of UV resistance layer, even if long exposure outside, its optical and mechanical performance were no significant changes.

Four sound barriers, special chemical resistance of the PC board

Polycarbonate at room temperature to weak acid, weak alkali and alcohol resistance performance is good, but in strong acid and alkali, benzene, chlorinated hydrocarbons and esters resistance performance is a bit poor, prone to dissolve, swelling or breakdown phenomenon. Because of its chemical resistance and temperature, internal residual stress size and length of exposure, so should pay special attention to before use.

Five, the special PC board of noise barrier in weight

Under the same thickness and area of PC endurance plate weight was only about half of the glass, so can save the handling and the difficulty of the construction noise barrier.

Six sound barriers, special sound insulation performance of the PC board

PC endurance plate sound insulation effect is higher than glass 3-4 db, noise barriers of transparent material of choice for sound insulation materials, PC endurance plate has been widely applied to highway sound barrier, sound barriers viaduct, expressway, railway noise barrier, rail traffic noise barrier, noise barrier Gao Tiesheng barrier, such as community noise barrier engineering of noise barrier.

Glass wool

Centrifugal glass WOOL (GALSS WOOL) is in the eighty s the international rise of new thermal insulation material, is a new member of the family of glass fiber, it adopts world advanced law centrifugal injection process, will take place in the molten state of the glass fibrosis and spraying thermosetting resin made from silk cotton material, through the thermal curing deep processing and multiple USES can be made with the series of products. It has a flame retardant, non-toxic, corrosion resistance, bulk density of small, low thermal conductivity, chemical stability strong, low moisture absorption rate, hydrophobic good, and many other advantages, is recognized as the most superior heat preservation, heat insulation, sound absorption performance material, has the very wide range of USES. With board, felt and pipe made of this material has a large number of used in construction, chemical, electronics, electric power, metallurgy, energy, transportation and other fields of heat preservation and heat insulation, sound-absorbing noise reduction, the effect is significant. Due to the material quality of a material soft, superfine fiber, less slag ball content, construction will not stimulate the skin, thus welcome by construction unit, be the first choice of the thermal insulation products.

Glass cotton products is the Shi Yingsha, feldspar, sodium silicate, boric acid as main raw materials, such as less than 6 microns made by high temperature melting fiber spongiform then through high temperature to finalize the design to create a variety of shapes, specifications of the products.

Product features:

1, light density, sound-absorbing coefficient, flame retardant and has excellent chemical stability.

2, moistureproof, prevent radiation.

Scope of application:

1, roof insulation, cold insulation, sound-absorbing material.

2, building insulation, cold.

3, cinema, television stations, radio stations, entertainment venues, sound-absorbing processing lab.

4, petroleum, chemical, thermal power, industrial heat supply and civil heating pipe insulation, such as cold.

Aluminum foam

Aluminum foam is made in pure aluminum or aluminum alloy after adding additive, pass foaming process, metal and bubble characteristic concurrently at the same time, belongs to a new type of porous sound absorbing material.

Aluminum foam sound absorption board and aluminum fiberboard are directly exposed to the atmosphere does not need the casing perforation plate and the filler, such as easy installation.

Aluminum foam sound barrier has the stable, sound absorption performance of the average sound absorption coefficient is greater than 0.64, the noise reduction coefficient NRC0.75 around for low frequency of traffic noise in the sound absorption performance is good, is higher than some other commonly used sound-absorbing material, and after the rain and dust absorption, absorption coefficient does not change, comply with the requirement of road noise barrier acoustics.

Aluminum foam sound absorption board can spray into all sorts of color, and the sound absorption performance is not affected, can greatly enrich the landscape sound barrier.

Aluminum foam sound absorption board and glass can be washed, and can achieve self-cleaning through natural rain, will not affect the acoustic performance; Once the dust, will not affect the acoustic properties, it will improve the high frequency sound absorption performance.

Aluminum foam with metal corresponding fire resistance, weather resistance, corrosion resistance, aging resistance, design the service life of 20 years.

Aluminum foam sound absorption board has good characteristics of anti-glare.

Aluminum foam sound barrier has been widely used in home, Shanghai lupu bridge, xupu bridge, A5 highway, zhongchun road elevated road are the application of aluminum foam material, and has passed the acceptance. The outer ring of Shanghai city pudong section is also installed applications.

Aluminum fiber

Aluminum fiber acoustic board is made up of two sides aluminum plate mesh aluminum fiber felt and aluminum foil sandwiched between them, after rolling forming a metal sound-absorbing material. It has excellent sound absorption performance, high tensile strength, ultra-thin lightweight, transport storage convenience, good weather resistance, good decorative, convenient processing and construction installation and recycling use, etc.

Low ultra-thin light: aluminum fiber acoustic board general at around 0.8 ~ 2.0 mm thickness, surface density in 1.4 ~ 3.2 kg/m2. Due to material minimum volume, transport storage is very convenient.

Low noise reduction coefficient of 1.35 mm thick, the NRC is 0.7, 1.8 mm thick NRC noise reduction coefficient of 0.9

Low: decorative panel can be sprayed color, color is rich and beautiful, integrating decoration effect and sound-absorbing effect.

Low processing and construction installation convenient: plank machinability is good, easy to drilling, bending and cutting. Construction of the installation process does not produce fiber dust flying environmental pollution and affect the health of workers, the construction is simple.

Low material plate big picture: aluminum fiberboard is to use the plastic roll forming, through plate are big. In addition to the plate, can also be processed into a variety of sound absorption in the shape of body.

Low recyclable use: material is pure aluminum metal manufacturing, reciprocal, no waste formed cause pollution to the environment, so it is itself a kind of environmentally friendly products.

Barrier acoustic

The amount of noise reduction and noise frequency noise barrier, the height of the barrier, and the sound source and the distance between the receiver and other factors. Noise reduction of the noise barrier effect relationship between the frequency components of noise is very big, high frequency sound of greater than 2000 hz - 2000 a 1000 hz or so of intermediate frequency acoustic noise reduction effect is better, but for around 25 hz low frequency sound. Is due to the acoustic wavelength longer easily from the above barrier diffraction in the past, so the effect is poor. In general, the high frequency noise barrier can reduce l0, 15 db. The height of the noise barrier, according to the distance between the sound source and receiver design, double the height of the barrier, then 6 db can increase the amount of noise reduction, in order to make the noise reduction effect is good, the barrier of the should try to make the barrier near the source or receiver.

Sound wave type

Sound waves and ultrasound

1. Sound people call can cause hearing the mechanical wave of sound waves (audio). Between 20 ~ 20000 hz frequency.

2. The sound frequency is lower than 20 hz mechanical wave called a sound.

3. The ultrasonic machine for ultrasonic frequency above 20000 hz.

Longitudinal shear surface wave

1. The p-wave particle moves along the direction of propagation of wave in the medium.

2. A shear wave medium particle is perpendicular to the direction of propagation and wave motion.

3. The surface wave propagation along the medium surface, wave amplitude decrease rapidly with depth.

Surface wave cylindrical wave spherical wave

1. The plane wave wavefront a wave perpendicular to the direction of propagation for plane county.

2. The cylindrical wave wavefront for coaxial cylindrical wave.

3. The spherical wavefront of concentric spherical wave.

Selection principle

The general principles of sound insulation material selection effect of noise reduction performance good, safe and reliable structure, material price economy, installation, low cost, durable, long service life, landscape coordination, beautiful and easy, etc. Details are as follows:

(1) the sound volume: the average sound insulation quantity should not be less than 35 db;

(2) the high absorption coefficient: the average absorption coefficient should not be less than 0.84;

(3) corrosion resistance durability: the product should have water resistance, heat resistance, uv resistance, will not lower the quality of performance or anomalies caused by rain water temperature changes. Products adopt aluminum alloy plate, galvanized volumes galvanized board, glass wool, H steel column surface of anticorrosion fixed number of year in more than 15 years.

(4) beautiful: can choose a variety of colour and modelling are combined, with the surrounding environment harmonious, form a beautiful scenery line.

(5) the economy: prefabricated construction, improve the work efficiency, shorten the construction time, saves ShiGongFei and artificial cost.

(6) convenience: in parallel with other products installation, easy maintenance, easy to update.

(7) light: sound-absorbing board series products have the characteristics of light weight, can reduce the bearing load of elevated light rail, highways, and can reduce the cost of the structure.

(8) fire: using superfine glass wool, due to its high melting point, nonflammable, fully meet the requirements of environmental protection and the code for fire protection.

(9) : high strength combined with climatic conditions in different parts of our country, fully test virtual wind load in structure design. Through the production line to suppress grooves increase strength.

(10) waterproof, dustproof, material design fully consider waterproof, dustproof, get wet in the rain in the dust or the sound absorption performance is not affected in the environment, structure has been set in the dirt drainage measures, avoid internal water components. Micro-perforated resonance cavity acoustic get wet in the rain in the sound absorption performance is not affected in the environment, particularly for the low frequency noise reduction.

(11) and durable: the product design has been fully consider the way of wind load, the transportation vehicle crash safety and the whole gas false open-air anticorrosion. Products adopt aluminum alloy plate, galvanized volumes galvanized board, glass wool, H steel column surface processing. In the warranty period, no corrosion, no variant, sound absorption, sound insulation effect is not reduced.

Advantages of outlook Crown fly edge noise barrier

1, low cost, not only the product production cost is low, and the products are light weight can dramatically reduce the elevated light rail, highways with heavy load, reduce the project cost;

2, strong under prescribed by ritual law: high strength, light weight, can satisfy the various areas of different climatic conditions on the wind load requirements;

3, acoustic performance is superior: magnesium the average amount of acoustic noise barrier is greater than 35 db, average sound absorption coefficient is greater than 0.84, and meet the requirements of every field of noise barrier;

4, fire prevention performance is good, magnesite cementing materials belong to inorganic non-combustible material, composite sound-absorbing material such as glass wool, perlite also has A good fireproof performance, makes the product has excellent fireproof performance, national a-class non-combustible material;

5, use good durability: magnesium the sound barrier waterproof, fireproof, corrosion resistance, resistance to ultraviolet ray, is not affected by rain, snow, wind and sand erosion of the bad weather, such as long service life;

6, installation is simple: magnesium light dead weight, noise barrier can be fabricated construction, high efficiency, short time limit, can save a lot of work in charge;

7, beautiful plastic: according to different needs can be used with the structure of metal material and pervious to light material combination, also can spray all sorts of color and design, in order to meet the requirements of landscape decoration.

8, energy conservation and environmental protection: magnesium raw materials used non-toxic harmless, noise barrier and the production process without heating, no poisonous gas release, is the state encourages the development of environmentally friendly products;

9, broad applicable scope: according to different needs for processing production magnesium the sound insulation board and magnesium the sound-absorbing board, suitable for highway, railway, the railway, culverts, tunnels and other transportation and all kinds of industrial workshop, workshop and residential area, etc.

prospects

As China's economy, accelerating urbanization, the rapid development of highway, railway, urban rail transit and other transportation to get fast development, the road in the construction of it through the population is concentrated in residential areas, road traffic noise generated by the nearby residents work, life and study has brought certain interference. National environmental monitoring results show that the road traffic noise in about 17% of the city belongs to the moderate pollution, 49% of the city's pollution, establish a solution to traffic noise pollution become urban road noise barrier is the main noise control. Magnesium the sound barriers because of its unique advantages obtained fast development, has been widely used in cities like Beijing, zhengzhou, guangzhou and chongqing.

application

Is mainly used in railway and highway noise barrier along the line,

Is mainly used for highway noise barrier composite, elevated roads, urban light rail, subway and other traffic acoustic noise reduction of municipal facilities, control of traffic noise influence on urban areas near, can also be used for factories and other noise acoustic noise reduction.

Divided into pure acoustic noise barrier reflective sound barrier, and the combination of sound absorption and sound insulation composite sound barriers, the latter is more effective sound insulation. Most of the noise barrier is chosen sound absorption and sound insulation of hybrid product, the characteristics of this type of products is the road noise generation and transmission characteristics of targeted control. Such as cars and road friction or locomotives and rail friction at the bottom of the road, voice through the upper screen diffraction characteristics, so in the design USES the sound absorption, the interval acoustic structure, which could effectively abate the noise diffraction; In the middle of the noise barrier use transparent reflective sound insulation board, can effectively interrupt the transmission of sound waves; At the same time also for the drivers and provide a wide field of vision environment for residents. Architectural acoustics field by acoustic treatment, and control the reverberation time and indoor sound environment, satisfies the requirement of professional venues

knowledge

1, the diffraction

Across the top of the noise barrier of the sound energy of diffracted sound to the point than there is no barrier of direct sound energy. The difference between the direct sound and sound diffraction of sound level, called diffracted attenuation, its value with that symbol delta Ld, and increases with the increase of Φ Angle. Diffraction acoustic attenuation of noise barrier is a sound, the sound point and noise barrier geometric relationships and frequency function, it is decided to sound screen 2 and transmission

Sound source of the sound waves through the sound barrier to the sound. Through the acoustic noise barrier energy depends on the surface density of the noise barrier, incident Angle and the frequency of the sound waves. The ability of acoustic noise barrier by TL of sound transmission loss evaluation. TL is big, the transmission of sound energy is small; TL is small, the transmission of sound energy, sound energy of transmission could reduce the insert loss of sound barrier, the insertion loss caused by transmission of lower quantity is called the sound transmission correction. Use symbols Δ Lt said. Normally in the acoustic design, the TL - delta Ld 10 db, or the transmission of sound energy is negligible, the delta Lt material 0.

3, reflection

Sound barriers when roads are built on both sides, and parallel noise barrier, sound waves will be multiple reflections between the sound barrier, sound barriers across the top of the diffraction to the point, it will reduce the insert loss of sound barrier, lower insertion loss caused by reflection waves called reflections fixed amount, use symbol delta Lr said.

To reduce reflections, sound barriers in additional sound absorption structure by the road side. Reflected sound energy depends on the size of the sound absorption coefficient of the sound absorbing structure of alpha, it is a function of frequency, to evaluate the acoustic noise barrier structure overall sound absorption effect, usually by noise reduction coefficient, the NRC. The main physical quantities barrier insertion loss.

Construction requirements

1. Construction on the roadbed foundation of sound barriers is synchronous with subgrade should be built, shall not be damaged due to its construction, the influence of subgrade stability and security. Construction should be the basis of noise barrier in track laying subgrade body after molding, and cable trough before construction; Before construction should find out the location of the subgrade on all kinds of pipeline; According to the basic size and noise barrier in the position of the shoulder cutting slot, it is forbidden to destroy all kinds of pipe cutting slot.

2. The basis of noise barrier shall be in accordance with the requirements of design position, shape, size, depth, the construction, foundation excavation shall not destroy the bed surface.

3. The sound barrier foundation embedment anchor rod, anchor hole grouting construction materials, construction methods should comply with the design requirements, shall not affect the security and stability of roadbed.

4. The basis of noise barrier shall be construction expansion joints according to design requirements. Basis of noise barrier every 20 m to 30 m long set an expansion joint. Construction should be combined with the site topography and determine the exact location of the expansion joints.

5. Basic noise barrier shall be according to the requirements of design embedded drainpipe, subgrade drainage outlet shall not water flushing; And without a frantic jumble rail line between sump drain junction foundation concrete construction shall not destroy the drain. Based at the top of every 2 m embedded ø 100 MML PVC pipes, sound barriers to discharge the inside shoulder the rain; Based in central variable cross-section every 4 m press 2% gradient embedded ø 75 mm straight shape PVC pipes, subgrade ontology to water penetration and cable trough drainage; Without a frantic jumble track subgrade line between collecting well connect the drain can be pouring in the foundation. Subgrade sound barriers should set drainage facilities, the lateral drainage outlet should avoid scour of subgrade slope, and to prevent leakage.

6. Basic noise barrier after all compacted filled with concrete, the surface should be smooth linking to the subgrade surface.

7. The sound barrier foundation concrete strength test shall comply with the provisions of this standard article 11.2.18.

8. The sound barrier pillar between foundation and cable trough, catenary, with the gap of shoulder do the waterproof layer shall be in accordance with the requirements of design. Foundation and pillar between cable trough, catenary, and shoulder are application of asphalt concrete such as the crack do the waterproof layer.

9. Basic position away from the center line of the line noise barrier, section size, depth of embedment of allowable deviation, quantity inspection and inspection methods shall comply with the provisions of the table 13.4.9.

Table based distance line noise barrier centerline, section size,

Allowable deviation of embedment depth, and amount of inspection and test methods

Serial number inspection projects allow deviation construction unit quantity inspection method

1 distance line the centerline position 0, + 20 mm

According to the basis of noise barrier quantity 10% sampling inspection

Amount of feet

2 + 20 mm cross section size feet

3 embedment depth of not less than design value level measurement