AEROCONCRETE ARRESTOR BEDSB.Tech, Mechanical (3/4), Gayatri Vidya Parishad College Of Engineering,Madhurawada, Visakhapatnam. By R.krithika P.Sri HariTeja

Abstract: Aeroconcrete (or Aerated Concrete) are manufactured by adding Aluminium powder or a foaming agent (hydrolyzed protein or a resin) which reacts with the concrete forming air bubbles or gases that are entrapped in it. These are responsible for remarkable properties of aeroconcrete. The aerated concrete outperforms conventional concrete by the advantages of lightweight, heat preservation, sound isolation, high strength to weight ratio etc. The strength of the aeroconcrete can be altered by using foaming agents of different densities. Aeroconcretes have become the important part of new-type construction materials, and possess bright development future. In this paper we shall discuss the extensive use of aeroconcretes in constructing arrestor systems (EMAS). An Engineered Material Arresting System provides enhanced runway overrun safety for commercial airports. Aircraft can do overrun the ends of runways, sometimes with disastrous consequences . Arrestor Beds provide a safety device for quickly arresting the movement of vehicles such as airplanes and motor cars by forming a retarding bed of crushable material made of aeroconcrete. The strength of the foamed material used must be such that the wheels of the vehicle running off the track and on to the bed will crush the foamed material, exerting a drag on the wheels thereby slowing the vehicle down. Aerated concrete having a density between 240-961 kg/m3 and compressive strength of 40- 200 psi is quite suitable. The decelerating effect may also be increased with depth of penetration into the aerated bed by employing foams of different densities and compressive strengths at different parts of the bed. Damage to aircraft during these arrestments has been minimal. EMAS technology is changing the standard for safety at airports. It has proven to have both reliable and predictable performance capability through live arrestments. EMAS has shown it can save lives. Keywords: Aeroconcrete, Arrestor Bed, EMAS, Decelerate

ACKNOWLEDGEMENT

We are very thankful to the department of civil engineering, Andhra University for giving us the opportunity to take part in symposium ACCESS 08.We are grateful to Prof. P. Markandeya Raju of G.V.P.C.O.E. for his valuable assistance.

From the Authors,R. KrithikaP. Sri Hari Teja

Introduction:Concrete is a construction material composed of cement (commonly Portland cement) as well as other cementitious materials such as fly ash and slag cement, aggregate (generally a coarse aggregate such as gravel limestone or granite, plus a fine aggregate such as sand), water, and chemical admixtures. The word concrete comes from the Latin word "concretus", which means "hardened" or "hard".

Conventional ConcreteAerated Concrete is a precast structural product made with all-natural raw materials. In 1914, the Swedes discovered a mixture of cement, lime, water and sand that expands by adding aluminium powder. The material was further developed to what we know today as aerated concrete (also called as cellular concrete). The reaction between aluminium and concrete causes microscopic hydrogen bubbles to form, expanding the concrete to about five times its original volume, making it lightweight. Modern concrete technology uses foaming agent that produces and stabilizes air bubbles formed in the concrete.

Depending on the type of curing method used, there are twp types of aerated concretes. They are:1) Non-Autoclaved Aerated Concrete (NAC)2) Autoclaved Aerated Concrete (AAC)NAC are air cured whereas AAC are cured at high temperatures and pressures in an autoclave.

Light Weight Aerated Concrete Floating in WaterAerated concrete has outperformed conventional or poured concrete in various ways. The air bubbles entrapped in the concrete are responsible for its various properties. Autoclaving of aerated concrete improves the compressive strength. The air bubbles increase the volume resulting in high strength to weight ratio. It is lightweight ,has high thermal insulation, sound isolation, fire and termite resistance, economical, sustainable solid block. Especially, it can not only make use of industrial waste residue, improve environmental pollution, and protect tillable field, but also create favourable social and economic benefits to take fly ash as the raw material of AAC block and board. Aerated concrete (i.e. aeroconcrete) is the perfect wall material to replace the traditional solid clay brick. Aeroconcrete (AAC) block and board have become the important part of new-type construction materials, and possess bright development future.Since the cost of fire clay bricks are going up making alternatives acceptable. Large companies like DLF are already using light weight aerated concrete blocks in high rise buildings. Production units for aerated concrete blocks have been set up in the country. There is good scope for setting up this unit in proximity to cities like Hyderabad and Visakhapatnam.

Differences between Aerated and Conventional Concrete:

Aerated ConcreteConventional Concrete

1)They are lightweight due to the presenceof air bubbles or gases entrapped in it. 1)They are relatively heavier than The aerated concretes.

2)they have a high R-value thusProviding a higher insulation level .2)They have an R-value less than1.25 of the aerated ones.

3)They have a lower compressive strengthAlmost 10% of conventional concrete.3)They have a higher compressiveStrength.

4)Has a higher sound absorbing characteristicWith an STC rating of 44.4) has a relatively lower soundAbsorption capacity.

5)Easy to use as they can be cut into anyShape using ordinary carpentary tools.5)They are not easy to handle.

6)They are non-toxic,fire-resistant .They can withstand temperatures upto 30000C andAbsorb thermal shocks.6)they are toxic,have less fireResistance.

7)They are highly energy efficient .7) They are less energy efficient.

8)They reduce the material consumptionAs their occupy five times the volume ofConventional concrete.8) Material Consumption is comparatively more.

9) Aerated Concrete walls are air tight9) They have air-gaps in between.

10) It is easy to manage the waste as they can be Recycled.

10)the conventional concretewaste cannot be recycled andAre not eco-friendly.

Manufacturing process:Cellular (aerated) Light Weight Concrete (CLC) can be manufactured by a process involving the mixing of fly ash, cement, coarse sand, fine sand and a forming agent in a mixer to form a thin slurry. The slurry is then poured in moulds and allowed to set. The blocks are then removed from the moulds and are cured by spraying water on the stack. They can be cured by Autoclaving with steam.The bulk density of the product varies from 400 to 1800 kg/cum. The process is carried out in the following steps.1. Mixing fly ash and calcined gypsum2. Mixing additives and cement3. Mixing lime4. Mixing blowing agent5. Pouring into moulds6. Cutting7. Curing8. Steam Autoclaving

A combination of the other materials can also be included in the mix, depending on the application and requirements, such as: Polypropylene fibre, Fibre steel, Quarry fines, Vermiculite, Fly ash, Volcanic Ash etc. AAC blocks can be cut with a handsaw and sculpted with a rasp, creating endless design possibilities.Curing:

Aerated Concrete Panels being Air CuredSince many of the properties of aerated lightweight concrete depend upon the successful process of curing, outlined below are some of the methods whereby its strength can be increased.Air Curing:This is probably the easiest and most popular method of curing. It is a slow, but acceptable system which enables a turn around of moulds every 24 hours on average, depending on the ambient temperature.

Steam Curing:When precast aerated lightweight concrete panels and slabs are made under factory conditions in order to obtain a relatively fast turn-around of moulds, it may be economic to induce an early strength into the concrete by applying heat from steam to the underside of the moulds. This causes a rise in temperature in the concrete and a resulting increase in strength.The reason for steaming from the underside is to avoid the increase in temperature creating small cells of compressed air with sufficient pressure to fracture the cement shell around the cell. Due to the weight of concrete above the lower layers this does not take place and by the time the temperature increases on the upper face, the cement has already acquired sufficient strength to resist the cells exploding off and giving a rough surface to the slab or panel.Depending upon the type of cement used in the mix, steam curing is not begun until at least five hours after casting, and even then the increase in temperature is well controlled and should not exceed 70C (160F). The extent of steam curing depends upon the climate but as a general rule it can be subdivided into 2 hours required for raising the temperature, 4 hours maintaining the temperature and 2 hours lowering the temperature slowly to avoid thermal shock.Especially, it can not only make use of industrial waste residue, improve environmental pollution, and protect tillable field, but also create favourable social and economic benefits to take fly ash as the raw material of AAC block and board. For many years, Aerated Concrete (AAC) has always accepted strong supports from the policies about reforming of wall material, tax policies and environment protection policies.

Water - Cement Ratio:The amount of water to be added to the mix depends upon the moisture content of the sand, but as an average figure, 40-45 litres of water is used for every 100 kilograms of cement. Additional water is added as a content of the foam, thereby bringing the total water: cement ratio up to the order to 0.6. In general, when the amount of foam is increased, as for lighter densities, the amount of water can therefore be decreased. The water: cement ratio should be kept as low as possible in order to avoid unnecessary shrinkage in the moulds, however, it should be remembered that, if the amount of water added to cement and sand in the first instance it too low, the necessary moisture to make a workable mix will be extracted from the foam when it is added, thereby destroying some of the foam which is naturally an expensive way of adding water to the mix.

Properties: 1. Lightweight 1. Energy Efficient1. Whole wall coverage and low air infiltration.1. Fire Resistant1. Acoustically Absorbent1. Weather Resistant.1. Long Lasting1. Environmentally Sound.1. Pest Resistant1. Easy to use1. Versatile1. Lightweight

Aero Concrete can be carved into any intricate design

ApplicationsThe use of lightweight concrete in building is becoming increasingly extensive. The following are some of the typical applications principally in use at present.1)Aeroconcrete with Density 300-600 kg/m (19-38 lbs/ft) made with Cement & Foam only in roof and floor as insulation against heat and sound and is applied on rigid floors (i.e. in itself it is not a structural material). It is used for tennis courts and interspaces filling between brickwork leaves in underground walls, insulation in hollow blocks and any other filling situation where high insulating properties are required.

High Rise Buildings made of reinforced Aerated Concrete2)Aeroconcrete with Density 600-900 kg/m (38-56 lbs/ft) Made with Sand, Cement & Foam is used for the manufacture of precast blocks and panels for curtain and partition walls, slabs for false ceilings, thermal insulation and soundproofing screeds in multi-level residential and commercial buildings.3)Aeroconcrete with Density 900-1200 kg/m (56-75 lbs/ft) Made with Sand, Cement & Foam is used in concrete blocks and panels for outer leaves of buildings, architectural ornamentation as well as partition walls, concrete slabs for roofing and floor screeds.

4)Aeroconcrete with Density 1200-1600 kg/m (75-100 lbs/ft) Made with Sand, Cement & Foam is used in precast panels of any dimension for commercial and industrial use, insitu casting of walls, garden ornaments and other uses where structural concrete of light weight is an advantage.5) Easy to use: It is use to cut and drill with any wood cutting tool. It actually cuts faster than wood. So it is widely used in creating different architectural shapes.6)Pest Resistant: With solid wall construction and finishes that bond to the wall there are fewer, if any ,rodents and insects to dwell in.AAC eliminates these entry points .Moreover, termites and rodents do not eat or nest in them.7) Environmentally Sound: The use of the AAC reduces the number of trees being cut to build with. Unlike wood, AAC is not vulnerable to water damage and provides less maintenance cost. Since AAC wrought or deteriorate and is impervious to fire damage, it potentially even saves the costs of demolition and reconstruction.Since AAC consists of approximately 80% air the finished product is upto 5 times the volume of raw materials used, making it even more resource efficient. Its manufacture requires little energy as compared to other materials and produces no waste products.8) Long Lasting: AAC has only been around since 1923 so there are hardly any homes over 80 years old. The scientific aspects of the material performance till now predict that homes made from AAC will last for hundreds of years.9) Weather resistant: AAC is one of the most durable building materials known to man. It has shown its strength against hurricanes, tornadoes, earthquakes & floods.10) Acoustically Absorbent: AAC provides excellent sound absorption with an STC- sound transmission class (rating of 44). So widely used in concert halls and constructions where sound insulation is required.

Aerated Concrete are resistant to thermal change.11) Fire Resistant: Most residential fires do not exceed 1200 degree centigrade AAC does not begin to break down until well over 3000 degree centigrade. Unlike conventional concrete, AAC is very resistant to thermal changes. This enables AAC to withstand the thermal shock of cold water from a firemans hose hitting it.

12) Energy Efficient: AAC has both high thermal mass and thermal inertia causing it to maintain constant temperature, whole wall coverage and low air infiltration. These combine and translate into energy savings which do not degrade and continue to appreciate over time.

Engineered Material Arresting System:Aircraft can and do overrun the ends of runways, sometimes with disastrous consequences. The Federal Aviation Administration (FAA) requires that commercial airports have a standard Runway Safety Area (RSA) where possible. At most commercial airports the RSA is 500 feet wide and extends 1000 feet beyond each end of the runway. The FAA has this requirement in the event that an aircraft overruns, undershoots, or veers off the side of the runway. The most dangerous of these incidents are overruns, but since many airports were built before the 1000-foot RSA length was adopted some 20 years ago, the area beyond the end of the runway is where many airports cannot achieve the full standard RSA. This is due to obstacles such as bodies of water, highways, railroads and populated areas or severe drop-off of terrain.

EMAS installed at the end of a RUNWAYThe FAA has a high-priority program to enhance safety by upgrading the RSAs at commercial airports and provide federal funding to support those upgrades. However, it still may not be practical for some airports to achieve the standard RSA. It is a known fact that it would be difficult to achieve a standard RSA at every airport, so the development of a new technology to provide an added measure of safety became quintessential and took form as an. ARRESTOR BED.

An Engineered Materials Arresting System (EMAS) i.e. an arrestor bed uses materials of closely controlled strength and density placed at the end of a runway to stop or greatly slow an aircraft that overruns the runway. The best material found to date is a lightweight, crushable concrete. When an aircraft rolls into an EMAS arrestor bed, the tires of the aircraft sink into the lightweight concrete and the aircraft is decelerated by having to roll through the material. This unique material allows passengers and crewmembers to exit the aircraft safely and for the aircraft to be removed from the arresting system easily, with minimal effects. Each EMAS application is engineered and customized in length, depth and strength to provide optimum performance for the aircraft mix at each location. The depth of the EMAS gradually increases as the aircraft travels into the arrestor bed, providing increasing deceleration when required by heavier or faster aircraft. Aircraft run out distance will be determined by the aircraft size, weight, speed and bed configuration.

The main benefits of an EMAS installation The EMAS technology provides safety benefits in cases where land is not available, where it would be very expensive for the airport sponsor to buy the land off the end of the runway, or where it is otherwise not possible to have the standard 1,000-foot overrun. A standard EMAS installation extends 600 feet from the end of the runway. An EMAS arrestor bed can still be installed to help slow or stop an aircraft that overruns the runway, even if less than 600 feet of land is available.

Arrestment of an aircraft which overshot the runwayEMAS provides a reliable and predictable capability to stop an aircraft before reaching an existing hazard (road, railroad, waterway, steep embankment, etc.) and is equally effective in doing so in dry and non-dry surface conditions. The system is environmentally friendly since it can be installed on the existing runway safety area. It also negates the loss of any needed operational runway as is required by other safety area enhancement options such as shortening the runway, or imposing declared distances. EMAS can provide further safety enhancement even in areas where there are adequate RSA available. This is particularly true in situation where there is a need to protect against a high level of danger for an overrunning aircraft REGARDLESS of available RSA length (into rivers, buildings, highways/rails, over cliffs, etc.). We have already seen some airports realizing the benefits of having both EMAS and a full RSA.

Theory of OperationMaterial Strength & Depth Varies to Provide Optimum Performance1. As the aircraft traverses the bed, the wheels crush the EMAS material creating a tire/material interface (refer to figure 1). Ff

Figure 1

2. It is the point of the tire/material interface that provides the resistive loads to decelerate the aircraft.3. The loads are placed on the aircraft landing gear and support structure4. Level of performance depends primarily on landing gear strength and runway safety area available.

Figure 2The Calculations:Initial kinetic energy of the vehicle rolling and crushing energy equals final kinetic energy of the vehicle. The calculation looks like this: mv^2 - mgd (area under the concrete stress strain curve)x(volume of crushed material) = 0 M is mass of the vehicle; V is velocity of the vehicle; is the coefficient of rolling friction; g, acceleration due to gravity; d is the distance covered before the plane comes to rest; As an aside, wind resistance and the change in potential energy due to the vehicle dropping into the bed were neglected. It was assumed that the accelerator was off once the vehicles entered the arrestor bed.

How is it produced? The arrestor bed is produced as pre-cast blocks. A factory installed jet blast resistant block protection system is applied to the raw blocks to enhance durability and protect against the effects of aircraft jet blast. Blocks that pass the stringent quality test limits established by the FAA are then transported to the runway safety area to be installed.

The Site Preparation Requirements for an EMASThe safety area is graded for drainage and longitudinal slope, adjusted if necessary, based on performance modeling of aircraft. The safety area is then paved (strength sufficient to support a rolling aircraft without deformation, not runway strength), from the runway end to the back of an EMAS. A concrete beam is constructed at the location. The length and width of the paved area are based on the arrestor bed size and location. The bed is located to minimize the handwork required during installation where blocks are cut to fit around lights. Any lights which will be in the EMAS arrestor bed are modified to 2-points of frangibility. Normally, electrical utilities requiring regular access are moved outside the bed footprint. Any special drainage issues are accommodated.

EMAS Installation and DesignAfter the site has been prepared, blocks are placed using forklifts with special clamping attachments, then pushed tightly against the neighboring blocks in the bed. Then a grid is marked to outline block locations. The block joints are then caulked and additional coats of water-resistant paint are applied to seal the bed and prevent weather damage.

Figure 3*The EMAS is typically the full width of the runway and the arrestor bed is set-back from the end of the runway.(Figure 3)

*The front of an EMAS includes a lead-in ramp to transition the aircraft into the material. (Figure 4)

Figure 4

*Beyond the runway width the sides of an EMAS are stepped to provide emergency vehicle access and passenger egress.(Figure 5)

Figure 5* On short runway safety areas an EMAS typically extends the length of the space available.

Duration of Installation

Installation of an Arrestor BedA typical program will vary considerably depending on the size of the arrestor bed, and the amount of site preparation work required. Once the design is completed, it typically would take about three to four months to produce and install an EMAS on one overrun safety area. The actual installation would typically take 4-6 weeks after site preparation is completed, depending on the bed size.Size of an EMASThe arrestor bed is the width of the runway, plus 16 to 24 feet for the stepped sides (to facilitate ARFF vehicle access and passenger egress), depending on the maximum depth of bed material. EMAS includes a paved rigid ramp, usually 75 feet long, in front of the arrestor bed. If sufficient safety area is available, a longer setback is normally used to provide the maximum performance possible.Performance of an EMAS* On long runway safety areas the arrestor bed set-back is increased and the system is sized for 70-knot performance .The speed reduction performance of a n arrestor bed is shown below. (Figure 6)

Figure 6

Cost of an EMASCosts for EMAS will vary greatly depending on the condition of the existing overrun, mix of aircraft to be controlled and available run out distance, cost and availability of support labor and on-site storage space available at the airport. In particular, site preparation requirements can also have a large impact on price.

Repair of an arrestor bed after an arrestment Damaged EMAS material is removed with front-end loaders and discarded. The aircraft is extracted using two tugs and straps attached to each main landing gear to pull the aircraft out backwards. New precast blocks are then installed and finish coats applied. Repair costs would normally be paid for by the insurance of the party responsible for inflicting damage to the EMAS system.Damaged material would be removed and replaced. In addition to aircraft wheel rut damage, any damage caused by fire/rescue vehicles would have to be replaced. The duration of the repairs will be related to the amount of material damaged. In the Saab 340 overrun at JFK airport in 1999, the repairs took only 12 working days to accomplish. The runway remained open between the time the aircraft was extracted from the safety area and the time the repairs were completed. After an arrestment (once the aircraft has been removed) but before the overrun arrestor has been repaired, the FAA has stated that airports may reopen runways. The FAA Advisory Circular for EMAS includes a design requirement that an EMAS can be repaired within 45 days after an overrun arrestment.

Normal Maintenance Normal maintenance consists of maintaining the protective surface coatings. This would include painting and caulking as needed, which can be performed by airport maintenance personnel. Proper maintenance will protect the underlying arrestor bed blocks from the environment, keeping excessive moisture out and prolonging the life of the system. In order to maintain durability, repaint of the entire bed may be required every 3 to 5 years. An arrestor bed should also be inspected regularly. It is recommended weekly drive-by inspections as well as a monthly walk of the bed. Any visible damage to the surface coatings should be repaired immediately to maintain durability.

Extent to which emergency and maintenance vehicles and personnel can traverse the EMASNon-emergency use on the bed by ARFF vehicles should be avoided since the tires will leave ruts. Similarly, access on the bed other than the maintenance vehicles should be avoided. EMAS site preparation includes paving around the perimeter of the bed to allow vehicles to drive around the bed for inspections and maintenance. Maintenance and other authorized personnel can walk on the arrestor bed without damaging the surface.What were the results of the fire tests in relation to aircraft egress and damage to aircraft?Fire testing was performed in order to meet the FAAs Advisory Circular requirement for EMAS; specifically that EMAS be non-sparking, non-flammable, does not promote combustion and does not emit toxic fumes or malodorous fumes in a fire environment after installation. We successfully demonstrated this through fire testing. EMAS itself is comprised almost entirely (about 98%) of aerated concrete which is inert with respect to fire. In the case of a fuel spill, EMAS does not readily absorb fuel nor does it readily allow the fuel to propagate throughout the bed, perhaps limiting the scope of the fire. However there are some minor components that are not inherently inert, mainly the Jet Blast Resistant (JBR) top. The top plastic trays are manufactured with a fire retardant in order to not promote combustion or emit malodorous or toxic fumes.

Latest enhancementsThe EMAS system enhancements include:*Plastic Bottom Tray with Integrated Forklift Slots that provides improved moisture protection from below and permits easier handling and quicker installation with standard equipment.

UV resistant and flame retardant Arrestor Bed*Plastic Top Cover that provides superior moisture and mechanical protection while virtually eliminating the need to paint the bed. The plastic material is flame retardant and chemical/UV resistant. *Butyl Rubber Seam Tape that provides superior, longer lasting sealing of block joints and substantially reduces installation time and effort. *Extruded Silicone Side Sealer that provides a higher quality seal on exposed block sides and is quickly installed with standard equipment.

Case Study:Airports with substandard runway over run areas are rethinking installing EMAS in light of the availability of improved materials and a demonstration of tragic consequences of failing to arrest an aircraft sliding off the end of runway.

1. Boeing 737 off the runway into the streetOn the Dec. 8, 2005, overrun accident at Midway International Airport in Chicago. Southwest Airlines Flight 1248, a Boeing 737-700, landed on snow-contaminated Runway 31C, rolled past the end of the runway at a groundspeed of about 50 knots, and knocked down a blast fence and a perimeter fence to encounter motor vehicle traffic on an off-airport street. A six-year-old boy was killed in a car hit by the 737.A computer model showed that the latest generation EMAS would have safely stopped the 737 at Midway of the Arrestor Bed, if it had been installed prior to the accident.

1. Air France being destroyed by post crash fireThe accident could have been worse akin to the Air France airbus A340 accident where the aircraft touched down at approximately 3800 feet down the 9000-foot runway. The aircraft was not able to stop on the remaining runway. It departed the end of the runway at a groundspeed of approximately 80 knots and came to rest in a ravine. The aircraft was substantially damaged during the overrun, and was subsequently destroyed by the post-crash fire. Thirty-three persons were taken to the hospital by ambulance. Of those, 21 were treated for minor injuries and released, and 12 (2 crew members and 10 passengers) were admitted with serious injuries. Nine persons who received serious injuries as a result of the impact lost their lives.

These kind of accidents can be prevented using EMAS (arrestor beds made out of aerated concrete) and can help save lives. This technology proved its worth in arresting planes which over shot the runways.

1. In May 2003, a McDonnell Douglas MD-11 operated by Gemini Air Cargo with a weight of about 2, 13,191 kg was safely arrested during a low-speed overrun on Runway 4R at Kennedy. The aircraft was extracted from the arrestor bed within a few hours.

A successful Arrestment1. In the January 2005 overrun on Runway 4R at Kennedy, a Polar Air Express cargo 747 with a weight of about 276,694 kg and an exit speed greater than 70 knots was stopped safely by the arrestor bed. Damage to aircraft during these arrestments has been minimal. Following the arrestment of a Boeing 747, airworthiness inspections and replacement of nine tires was performed and the 747 returned to normal flight operations within a few days.

Wheels of 747 penetrated into the aeroconcrete arrestor bed

Conclusion:"EMAS has shown it can save lives and it should be deployed at many more than the 14 U.S. airports that currently have this proven safety system in place." Joan Bauerlein FAA's Director of Aviation Research and DevelopmentAeroconcrete should be extensively used in the construction of arrestor beds. EMAS technology is changing the standard for safety at airports across the country to be based on performance. It has proven to have both reliable and predictable performance capability through live arrestment, even during inclement weather. With an EMAS, there is a potential to minimize environmental impacts & costs by not having to do excessive fill and build-out, to improve safety areas at a faster rate than the full build-out option, and also to have superior performance over a standard safety area.From 1995 to 2004, 71 percent of the worlds jet aircraft accidents occurred during landing and takeoff .Landing overruns, landing undershoots, takeoff overruns takeoff are the major types of accidents. To help improve safety we require runways to include a runway safety area (RSA) a graded and clean area surrounding the runway that should be capable, under normal (dry) conditions, of supporting airplanes without causing structural damage to airplanes or injury to their occupants.The objective of this paper is to highlight the importance of EMAS and how they can help in making our country's airports safer by saving lives. It would be fruitful if this new technology known as EMAS is installed in all the airports of our country.

References:

1. Concrete Technology By A.M. Neville & J.J. Brooks1. The World Wide Web: * www.wikipedia.com *www.polymertech.com *www.faa.gov.in *www.discoverysmashlabs.in *www.esco.emas.com

Authors: R.Krithika (9866236992) & P.HariTeja (9000010800)Gayatri Vidya Parishad College Of Engineering

Authors: R.Krithika (9866236992) & P.HariTeja (9000010800)Gayatri Vidya Parishad College Of Engineering