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Helpful information about the basics of surveying

The Dangers of Surveying

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From busy roads to stormy seas, a surveyor’s working environment is often dangerous. The need to stay alert to serious hazards while carrying out complicated tasks can make the job all the more challenging. But surveying is governed by comprehensive rules and regulations designed to keep surveyors and anyone in the vicinity of their work safe, and with meticulous planning and attention to detail, the risks can be kept to a minimum. Here are a few examples of the hazards that surveyors face every day, along with some of the measures that can be taken to stay safe on the job:

Roads

Surveying roads and highways can be particularly hazardous. Surveyors often have to complete time-consuming projects close to fast-moving traffic. To do this safely, good preparation is essential, and a plan of road networks must be studied carefully before work starts. When work is underway, it’s essential to pay close attention to the traffic, regardless of how demanding the task is. Cones and signs can be placed on the roadside to make drivers aware that surveyors are active, and the distance that surveyors must stay from moving traffic is closely regulated. Working outside for long periods is tiring, so regular breaks are also important.

Travel

Travelling to far-flung corners of the globe is one of the best aspects of surveying, but it can also be one of the most hazardous. Vaccinations may be required before setting off to minimise the risk of illness. If surveyors are working in thick undergrowth, special protective clothing may need to be worn to prevent snake or insect bites. It’s important to prepare for the worst, especially when working in remote areas. Surveyors understand the risks involved in working in inhospitable environments and are ready to act fast if anyone is injured.

Buildings

Surveying around and inside buildings presents a range of health and safety concerns. A fire risk assessment is crucial to establish the potential for a fire to break out and create a plan for how to keep the risk of one starting to a minimum. Asbestos is still present in many older buildings and can cause mesothelioma when inhaled, which is more likely to happen when work is underway and the asbestos is disturbed. Another concern is Legionnaire’s Disease, a lung infection which can be spread by water droplets in air conditioning systems. The structural integrity of the building is a major concern, and a detailed assessment should be carried out before work begins.

Electricity

Utility mapping and railway surveying often involve working close to electricity and gas – both of which can be seriously dangerous if caution isn’t exercised at all times. A detailed risk assessment which includes electrical hazards is crucial, and all workers must be able to recognize the dangers of overhead power lines, electrical wiring and buried cables. It’s particularly important that all underground utilities are located before the site is excavated or otherwise disturbed.

Water

From reservoirs to wild stretches of coast, surveyors are regularly required to assess bodies of water. Detailed weather forecasting is essential, especially for oceans and rivers, where changing tides, swell and wind can cause calm conditions to quickly deteriorate. Comprehensive safety measures must be in place, and all workers should know what to do in an emergency.

Heavy Equipment

Surveying on construction sites often involves working close to bulldozers, excavators and dump trucks. Close communication between everyone on the site and careful planning is essential to minimise the risk, and close attention must be paid to any equipment being used nearby.

Accuracy in Land Surveying

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 Surveyors have always strived for accuracy. When land surveys are flawed, all kinds of problems can arise. Poor-quality surveys can cause legal issues, serious hazards and lengthy setbacks. From construction sites to boundary disputes, surveys are expected to be detailed and highly accurate. By mapping topographic and hydrographic features with accuracy, surveyors lay the foundations for a range of large-scale developments – and if the foundations are shaky, entire projects can collapse.



  Accuracy vs Precision

 While ‘accuracy’ and ‘precision’ are often used interchangeably, it’s important to note that they have separate meanings in surveying. ‘Accuracy’ refers to how closely a measurement or observation comes to representing a true value. ‘Precision’, on the other hand, refers to how closely repeated measurements or observations come to duplicating measured or observed values.

  Surveying Accuracy Through the Ages

  In ancient civilizations, surveyors’ main goal was to establish and maintain property boundaries. They used rudimentary tools, such as knotted rope, Gunter’s chains and compasses – and the degree of accuracy they achieved varied dramatically. There’s evidence of land surveys having been carried out by the ancient Egyptians, as far back as 3000BC. The Egyptians pioneered various techniques, some of which remain important today. Using geometry and tools which seem basic by modern standards, they surveyed large sites with reasonable accuracy. But the level of accuracy they accomplished would be unacceptable now. Surveying technology and methodology is still evolving and standards continue to be raised. Although many of the fundamentals of surveying have barely changed for centuries, the tools of the trade have been transformed by an industry which has always endeavoured to reach higher standards and more advanced capabilities.

  Tools Required for Surveying Accuracy

  As surveying tools have advanced, so has the level of accuracy which can be achieved. The total station, for example, is now an essential tool which enables surveyors to measure distances using a real-time kinematic GPS system, to approximately 20mm horizontally and 30-40mm vertically. Total stations are now fully robotic and capable of electronically sending detailed point data and connecting to a global positioning system (GPS). 


  GPS systems also play an important role in ensuring accuracy in land surveys, although they don’t perform as well on sites with dense tree or building cover. Increased data collection, remote location and sensing and computing power is helping the profession to reach previously unattainable levels of accuracy, and surveyors can now provide extremely detailed data for varying surfaces and site  conditions. In recent years, UAVs and LIDAR have helped surveyors to map a range of terrains more accurately than ever.

Methodology for Accuracy in Land Surveys

Many of the principles that determine accuracy in land surveying have barely changed over the centuries. The profession relies on fundamental mathematical theories, such as trigonometry, calculus and geometry. The methodology used often depends on the type of survey. For example, surveyors covering large expanses of land will use techniques which account for the curvature of the Earth, while for smaller areas, the curvature of the Earth is generally eliminated.

Nain Singh Rawat

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Nain Singh Rawat

Nain Singh Rawat was one of the original Indian land surveyors, or ‘pundits’, who explored the Himalayas for the British in the 19th century. He played an important role in the Great Trigonometrical Survey of India, travelling in disguise, usually as a Tibetan monk, and hiding his measurements in prayer wheels. Rawat mapped the trade route through Nepal to Tibet, determined for the first time the location and altitude of the Tibetan city of Lhasa and surveyed huge swathes of Tsangpo, the major river through Tibet. Remembered as “short, stocky and stubborn”, he received a gold medal from the Royal Society in 1876. Following Rawat’s series of missions, Colonel Henry Yule praised him as having “added a larger amount of important knowledge to the map of Asia than any living man”.

Growing up in Johar Valley
Rawat was born in 1830, in the village of Milam, in the Johar valley, at the foot of the Milam glacier. During the coldest months of the year, the villagers would leave the region due to the extreme cold, and Rawat accompanied his father on several winter trips to the markets of western Tibet, where he learned the Tibetan language and customs. In 1855, at the age of 25, Rawat was employed by German geographers, Adolf and Robert Schlagintweit, who had been sent to carry out a detailed land survey of northern India and were told of Rawat’s knowledge of the area. Between 1855 and ’57, he accompanied the Germans to the remote lakes of Manasarova and Rakas Tal, before continuing on to Gartok and Ladakh.

The Great Trigonometric Survey of India
In 1863, Rawat and his cousin were appointed to work for the office of the Great Trigonometric Survey of India, the ambitious goal of which was to map the entire Indian subcontinent with scientific precision. The survey would establish the British territories in India and successfully measure the Himalayan mountains of Everest, K2 and Kanchenjunga. It would also see the first accurate measurements of a section of an arc of longitude and measurements of geodetic anomaly, both of which were important in the development of land surveying.

During Rawat’s two years of training he learned to use surveying equipment, including a sextant and compass. He was intelligent and determined, and was able to identify the major constellations by the end the two years. Due to the sensitive and dangerous nature of the project, Rawat and his fellow-trainees were also taught how to take measurements without attracting the suspicion of locals, by measuring distance with a combination of footsteps and rosary beads. The explorers would embark on their missions disguised as monks, with surveying tools hidden in their prayer books and cowrie shells.

Surveying Tibet in Disguise
Rawat left Kathmandu in 1865 and travelled more than 1,000 miles to Tashilhunpo, where he met the Panchen Lama, and Lhasa, where he met the Dalai Lama. Here, his cover was blown by a pair of Kashmiri Muslim merchants, but rather than reporting him to the authorities, they bought his watch for a small sum. He continued to Lake Manasarovar before returning to India and from 1873 to ’75, made a perilous journey from Leh in Ladhak to Assam.
In recognition of his achievements, The Royal Geographical Society presented Rawat with an inscribed gold chronometer and the Victoria Medal. He also received an inscribed watch from the Society of Geographers of Paris, and was granted two villages by the Indian government. Rawat died of a heart attack in 1877, having kept detailed diaries of his travels.

William Roy

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William Roy was a Scottish engineer and surveyor whose innovative geodetic mapping techniques played an important role in the development of surveying. He mapped the inhospitable Scottish mainland, created ground-breaking battle plans for the military and developed on-ground triangulation in surveying. But perhaps his most important legacy is the Ordnance Survey of Great Britain, which was a continuation of his Anglo-French survey and began shortly after his death.

Early Life & Surveying the Scottish Highlands
Roy was born in South Lanarkshire, in 1726. One of the few things known about his early life is that a number of his family members worked as factors, supervising the estate of wealthy Lairds, and he grew up in an environment in which land surveys and mapping were common. After he attended Lanark Grammar School, he is believed to have moved to Edinburgh, where he developed his surveying skills, probably as a civilian draughtsman at Edinburgh Castle’s Board of Ordnance. He became a respected land surveyor and was soon carrying out private surveys at the Callander family’s Craigforth estate. In 1747, Roy was employed to assist with a military survey of the Scottish Highlands under the command of the Duke of Cumberland. Roy had no military rank but Lieutenant-Colonel David Watson appointed him as an assistant to the quartermaster, who led a team of six soldiers. By 1752, the Highlands had been surveyed and the project was extended to cover the Lowlands. But it was cut short when the Seven Years War began. Reporting on the measurement of the Hounslow Baseline, Roy wrote that the map was “in an unfinished state and is to be considered as a magnificent military sketch rather than a very accurate map of the country, and it would have been completed, and many of its imperfections no doubt remedied, but for the breaking out of war in 1755”.

Campaigning for a National Land Survey
In 1756, Roy was posted to South England, where he assessed the coasts’ readiness for a French invasion, which was expected. He then went to France, where he developed a new technique for creating battle plans, which was praised as clear and user-friendly, and adopted by the military. By the end of the war, in 1763, Roy was a lieutenant colonel in the regiment and director of the engineers of the Board of Ordnance. He returned to London, where he proposed a comprehensive national survey or, as he put it, “a good military plan or map of the whole country”. He felt strongly that the survey should cover not only the vulnerable southern coasts, but the whole of the UK. Due to the expense of the Seven Years War, and later, the American War of Independence, the survey was considered too expensive.

Laying the Foundations for the Ordnance Survey of Great Britain
In 1765, Roy became surveyor-general with a direction to "inspect, survey and make reports from time to time of the state of the coasts of this Kingdom and the islands". He travelled extensively and his sketches and plans are now kept at the British Library. He completed topographical surveys of Middlesex, Surrey, Kent and Sussex using his new Ramsden Theodolite, and established the principal of on-ground triangulation in surveying. Aged 57, Roy started his Anglo-French Survey, mapping the relative positions of Greenwich Observatory and the Paris Observatory. First, he measured bases at Hounslow Heath and Romney Marsh, next, he measured the angles of the triangles and finally, he made a calculation of all the triangles. Roy died in London, in 1790, and a year later, the Ordnance Survey of Great Britain began, as an extension of his Anglo-French Survey. His use of scientific advancements and mathematical formulas paved the way for geodetic surveying and he is considered one of the fathers of modern surveying.

James Cook

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Captain James Cook was an English explorer and surveyor who sailed around the world, mapping vast expanses of previously uncharted territory. Cook was the first explorer to circumnavigate New Zealand and cross the Arctic Circle, and the first European to make contact with the eastern coast of Australia. He was also the first to make contact with the Hawaiian Islands, but it was here that his life came to a violent end. Renowned for his seamanship, courage and land surveying skills, his legacy has had a massive influence on surveying, and memorials to him are scattered across the globe.

Natural Talent for Surveying & Cartography
Cook was born in the village of Marston, Yorkshire, on November 7, 1728. As a teenager, he became a merchant navy apprentice in Whitby, with the Walkers, who were prominent local ship owners. He studied algebra, geometry, navigation and astronomy before completing his apprenticeship and starting work on trading ships in the Baltic Sea. Cook quickly moved through the ranks and was promoted to mate on the collier brig, Friendship. In 1755, he joined the Royal Navy and was soon qualified to navigate a King’s Fleet ship. During the Seven Years War, he was master of the Pembroke and was involved in the Battle of the Plains of Abraham. His talent for surveying and cartography enabled him to map the entrance to the Saint Lawrence River, which allowed General Wolfe to launch an important stealth attack on the plains.

Hydrographic Survey of Treacherous Newfoundland Coast
During the 1760s, Cook battled against the elements to survey the rugged Newfoundland coast, aboard HMS Grenville. With the help of local pilots, who he employed to look out for rocks and other hazards, he carried out detailed surveys of huge stretches of the treacherous and previously uncharted coastline. Cook used precise triangulation to carry out highly accurate hydrographic surveys of the island. His five seasons in Newfoundland resulted in the creation of the first good-quality, large-scale maps of the region. Following his time in the stormy seas around the island, Cook said he intended to go “not only farther than any man has been before me, but as far as I think it possible for man to go”. Mapping New Zealand on First Major Expedition

In 1768, at the age of 39, Cook embarked on the first of three celebrated voyages, sailing to the Pacific Ocean to observe the transit of Venus across the Sun for the Royal Society. Now ranked lieutenant, he left England aboard HMS Endeavour, rounded Cape Horn and continued westward, to Tahiti, where his observations of Venus were made. He then sailed to New Zealand, where he surveyed the entire coastline before continuing to Eastern Australia, where his expedition made first contact with an aboriginal tribe.

Searching for Terra Australis
In 1771, Cook was promoted to the rank of commander and a year later he was commissioned to lead an expedition to locate Terra Australis, a hypothetical continent which was based not on surveys but the theory that continental land in the Northern Hemisphere must be balanced by land in the south. HMS Resolution set off on an extreme southern latitude and the expedition became the first to cross the Antarctic Circle. Cook covered a massive expanse of ocean in his fruitless search for the mysterious continent, claiming South Georgia for Britain and discovering the South Sandwich Islands. His reports upon returning to England finally put an end to the myth of Terra Australis.

Ill-Fated Voyage to Hawaii
In 1776, Cook embarked on his last voyage to locate a Northwest Passage around the American Continent. He became the first European to make formal contact with the Hawaiian Islands before continuing to the Oregon coast. He sailed to Vancouver Island, where he made contact with the people of the First Nations village of Yuquot, before exploring and surveying the coast, to the Bering Strait. He then returned to Hawaii, where he explored the island and was reportedly treated as an incarnation of a Polynesian god. But when he tried to leave the island to continue his explorations, the mast of his ship broke and he returned to land. Tensions escalated and Cook was struck and stabbed to death by Hawaiian villagers.

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