importance of accuracy in land survey

Accuracy is one of the most important factors of land surveys. The purpose of a land survey is to accurately map and designate land boundaries. Any
inaccuracies can lead to potential legal issues down the track. Some types of land surveys require even more accuracy than others as they are used to help
establish where to construct buildings by taking into account topographic and hydrological features such as sewage systems and trees. Any inaccuracies could
cause difficulties in the building process.
The accuracy of land surveys is particularly important when they are used for map making as the wider community relies on the accuracy of maps and assumes
that they are precise documents. Note the 2005 version of ALTA specifications, "ALTA" stands for American Land Title Association, states a Positional Accuracy
of 0.07 feet or 20mm in new money, plus 50 parts per million. Many of the modern instruments used by a Land Surveyor have an accuracy of distance
measurements to within 2mm +/- 2 ppm but that alone does not assure compliance with the ALTA standards. The ALTA Standards require that these condition
are taken into account: The Relative Positional Accuracy may be tested by either:
1. Comparing the relative location of points in a survey as measured by an independent survey of higher accuracy or; In other words the survey would required
to be a traverse ending at its point of origin, beginning and ending on two different points of higher order. These higher orders can be monuments can be NGS
monuments, or monuments established on an older survey where the location was determined in accordance with condition 2 as here.
2. the results of a minimally constrained correctly weighted least square adjustment of the survey.
The surveyor needs to apply a squares adjustment program. Therefore the surveyor needs to know the accuracy standards of their equipment and surveying
techniques. This means they must know the distance and angular measurement specifications of their instrument and an estimate of such things as centering
tolerance.

Surveying Equipments - New

Recent development in technology has provided some of the finest surveying equipments present today.
Moreover, with the introduction of global positioning system, the methods of surveying have also totally
changed. GPS has not only made surveying faster but has increased the accuracy to amazing heights. GPS
works with the help of satellite systems which provide accurate data directly on the computer screen. Various
types of GPS equipment is available, from basic to highly advanced. Some GPS equipment even have night
vision which facilitates surveying during the night time. However, it is said that though GPS helps in
acquiring the exact position of the land; it does not provide good results in dense forest areas or concrete
constructions. For this reason, an instrument known as total station is used along with the GPS.
Total station is a theodolite with an Electronic Distance Measurement Device.
Total station has also been one of the reasons behind the drastic change of
technology in the surveying field. EDMD shifted the surveying technology from
optical mechanical devices to digital electronic devices. In spite of just being
distance measuring equipment, total station can also be used for leveling when
adjusted in a horizontal plane. Most of the ultra-modern surveying devices are a
combination of one or more of these devices.
There is a long list of surveying equipment available in the market today. The
selection of particular equipment depends on the type of application and accuracy
required. Though all these equipment provide a wide range of options to surveyors,
it is advisable to have a thorough knowledge of both, the equipment and the desired survey. This would not
only help in bringing accuracy to the work but would also save considerable time and money.

surveying equipments-old

urveying Equipments - Old
In ancient times surveying equipment included chains, compass, solar compass, transit, theodolite and more.
Chains with equal size links were used to measure distance between two required points. A compass was
used to measure the direction of a line that was being surveyed. A solar compass was used for measuring
both the direction and latitude of a particular point with the help of sun and stars. A Solar Compass could
also measure horizontal angles and the “true north” of a particular place. A metallic measuring tape was
used to measure shorter distances.
As technology gradually advanced with time, instruments used for surveying also improved. Horizontal and
vertical angles were measured using a simple theodolite whereas different heights were measured by a basic
level. Measuring wheels were also initially used by surveyors to measure long distances in a short duration of
time. Measuring wheels came in two types: mechanical and electrical, and both worked on the same principle
of rolling the wheel from the start to the end point.
In the early 1900s, surveyors started to use surveying equipment such as planimeters, theodolites, automatic
levels and measuring wheels. A planimeter is the best known tool for measuring asymmetrical land areas as
they eliminate the need for charts or manual calculations; whereas a theodolite allows measuring of
horizontal and vertical angles. A theodolite consists of a movable telescope attached over perpendicular axis.
It provides precise measurement of angles and is an integral part of every surveying tool kit. A transit is a
type of theodolite but has less precision.
An auto level or a dumpy level is also a type of surveying equipment used for measuring horizontal levels. It
consists of a telescope like device fitted on a tripod stand. Auto level, tilting level, and self-leveling level are
all types of leveling instruments, each providing different rotating capabilities.
Most surveying instruments are fixed on a tripod, which acts as a support. As the name suggests, tripods
have three legs with length varying capability. Many of these equipments are still used by surveyors around
the

AAC block

AAC Blocks also known as autoclaved cellular concrete ( ACC ) or autoclaved lightweight concrete ( ALC ), was
invented in the mid-1920s by the Swedish architect and inventor Johan Axel Eriksson. It is a lightweight, precast
building material that simultaneously provides structure, insulation, and fire and mold resistance. AAC products
include AAC blocks , AAC U Blocks AAC wall panels , AAC floor and roof panels , and AAC lintels .
AAC Blocks ( Autoclaved Aerated Concrete - " AAC ") a unique and excellent type of building materials due to its
super heat, fire and sound resistance, AAC blocks is lightweight and offers ultimate workability, flexibility and
durability. Its main ingredients include sand, water, quicklime, cement and gypsum. The chemical reaction due to
the aluminum paste provides AAC its distinct porous structure, lightness, and insulation properties, completely
different compared to other lightweight concrete materials.
Aerated Concrete Blocks - AAC is produced from the common materials lime,
sand, cement and water, and a small amount of rising agent. After mixing and
molding, it is then autoclaved under heat and pressure to create its unique
properties. AAC has excellent thermal insulation and acoustic absorption
properties. AAC is fire and pest resistant, and is economically and
environmentally superior to the more traditional structural building materials
such as concrete , wood, brick and stone.
AAC BLOCKS begins as a slurry mix of lime, sand, cement and water, and a small amount of rising agent.
For reinforced panels , a welded steel cage element is placed into the molds prior to pouring in the slurry.
Once the slurry is poured in, the mixture begins to foam and rise up completely around the reinforcing cage.
Once the rising process is complete the cage and the AAC are completely integrated and ready to be placed into
the autoclave for the curing process.

CLC block

CLC is called as Cellular Light Weight Concrete and it is also called as Foam Concrete. Cellular Light Weight Concrete (CLC)
is a version of light weight concrete that is produced like normal concrete under ambient conditions. CLC Blocks are a
cement-bonded material made by blending slurry of cement. Stable, pre-formed foam manufactured on site is injected into
this slurry to form foam concrete. Fresh foam concrete looks like a milk- shake and the volume of slurry in the foam dictates
the cast density of the foam concrete.
Are you worried about rising construction costs of projects ?
If yes, then CLC blocks is your answer. CLC blocks are a cement-bonded material made by blending slurry of cement. Stable,
pre-formed foam manufactured on site is injected into this slurry to form foam concert. Fresh foam concrete looks like a
milk-shake and the volume of slurry in the foam dictates the cast density of the foam concrete.
Why should a CLC Block Plant Be setup ?
Advantages
Applications
Raw Material
Procedure of Making CLC
Aqueous foam is produced from the foam generators (IFG) and injected into slurry of cement, fly ash and water in foam
concrete mixture (IFM). It creates many small air cells which are uniformly distributed throughout the concrete and create
cellular from 300kg/m3 to 1800kg/m3 with compressive strength between 5kg/cm2 to 200kg/cm2. The volume of air cells
in foam concrete determines the density and strength. The final mixture is then used for different applications without any
vibration or compaction. Fly ash which is a waste-product at thermal power stations. The foam concrete is thus a green
building material.
Comparison between CLC blocks and bricks
Parameters CLC Blocks Burnt Clay Bricks
Basic raw materials Cement, fly ash, water and foam Top agricultural soil, primary energy
input
Dry density kg/m3 600/800 1900
Ageing Gains strength with age (Like
conventional concrete)
No
Sound insulation Superior Normal
Eco friendliness - Pollution free
- No primary energy consumption
- Consumes fly ash (an hazardous
industrial waste material)
- Creates smoke
- high energy consumption
- wastes agricultural land
- soil erosion
- banned in more and more
countries
Thermal Insulation High thermal insulation Normal thermal insulation
Compressive strength Compressive strength is more than
other bricks.
Compressive strength is less
Water absorption capacity CLC is a light weight block where
water absorption is less as
compared to redbrick and fly-ash
brick
Redbricks and fly-ash brick absorb
more water than CLC blocks
CLC Block sizes
Size in MM No of Block in one m3
600 x 200 x 100mm 83
600 x 200 x 150mm 55
600 x 200 x 200mm 41
600 x 200 x 250mm 33
Comparison between CLC Blocks and AAC Blocks
Parameters CLC Blocks AAC Blocks
Basic raw materials Cement, fly ash, water and foam Cement, lime, specially grinded sand,
aeration compound, high primary
energy input
Production process and set-up Using ribbon mixer and foam
generator
Produced only in well established
plant, equipped with steam boiler
and high pressure auto-claves
Dry density kg/m³ 600/ 800 400/ 700
Compressive Strength kg/cm2 30- 40 20- 40
Usage Thermal insulation , partitions, non-
load bearing blocks
Non-load bearing panels and blocks
Aging Gains strength with age (like
conventional concrete)
No aging Loses strength, if not
protected against humidity
Thermal conductivity (W/mK) 0.09 – 0.12 (depending on density) 0.09-0.15 (depending on density)
Eco friendliness - Pollution free
- No primary energy consumption
- Consumes fly ash (an hazardous
industrial waste material)
- Pollution free
- High energy consumption