All techniques
Before undertaking any significant construction/development project or environmental improvement project, it may be necessary to perform a topographic land survey to identify various features and elevations of the land. Point to Point Land Surveyors, Inc. has many years of experience in conducting these surveys with remarkably accurate results.
Read & understand more about land survey below.
Important terminology
While the standard land survey deals primarily with marking out the boundaries of a parcel of land, a topographic survey is primarily concerned with noting the natural and manmade features on the land itself. These may include hills, ravines, streams, trees, fences, buildings, and other improvements over the natural state of the land. A topographic survey shows the location, size, and height of these types of improvements, as well as gradual changes or contours in elevation. Unlike boundary or residential land surveys, a topographic land survey focuses more on elevation than on horizontal measurements. Most of these measurements are taken either with a surveying-quality GPS unit, or with an electronic EDM instrument. The results of the topographic survey are not marked using stakes or other landmarks, but are instead drawn as contour lines on a map of the land (topographic surveys are sometimes called contour surveys). Today, sophisticated computer programs allow for digital versions of these maps, as well as interactive elevation views of the land. The data may be used in CAD programs, where it can be manipulated by engineers or architects to demonstrate how the topography will change through planned improvements.
Topographic land surveys have many uses. Nearly all construction projects begin with a topographic land survey, which describes the starting point of the land before improvements are made. Engineers and architects use them as an aid in designing buildings or other improvements to be situated on the property, as existing features may influence their design or decisions on where structures can and cannot be placed on the property. Topographic surveys may also be used when creating plans for drainage ditches, grading or other features, using the natural landscape as the basis for such improvements. Government agencies may also require topographic surveys for any of a number of reasons—for example, as regulatory requirements for construction codes, or as part of environmental restoration projects.
Topographic land surveys are also useful when a parcel of land that was previously in use is being redeveloped—for example, an abandoned quarry or landfill, a site where a building was demolished, or on a site where the topographic data is changing. In these cases, a topographic survey provides an accurate view of how the land has been changed by its use, allowing for better planning for future use.
Topographic land surveys are also useful when a parcel of land that was previously in use is being redeveloped—for example, an abandoned quarry or landfill, a site where a building was demolished, or on a site where the topographic data is changing. In these cases, a topographic survey provides an accurate view of how the land has been changed by its use, allowing for better planning for future use.
A cadastral survey plan is basically a property boundary survey. They are primarily carried out for legal purposes so as to accurately establish land ownership boundaries and usage.
Cadastral surveys show the boundaries of properties between neighbours and may include items such as easements, which are the right to cross or use someone elses property for a particular reason.
Cadastral surveys show the boundaries of properties between neighbours and may include items such as easements, which are the right to cross or use someone elses property for a particular reason.
Cadastral or property boundary surveys are needed when:
1) New parcels of land are created i.e. a new estate or large land development
2) You want to subdivide your block and get several new land titles
3) Neighbours want to check their property boundaries prior to fencing or building on or near the boundary
4) You want to create and grant an easement for access or use by another party
For existing properties where boundaries need to be redefined, these surveys are commonly known as repeg or re-establishment surveys.
1) New parcels of land are created i.e. a new estate or large land development
2) You want to subdivide your block and get several new land titles
3) Neighbours want to check their property boundaries prior to fencing or building on or near the boundary
4) You want to create and grant an easement for access or use by another party
For existing properties where boundaries need to be redefined, these surveys are commonly known as repeg or re-establishment surveys.
Levelling (or Leveling) is a branch of surveying, the object of which is: i) to find the elevations of given points with respect to a given or assumed datum, and ii) to establish points at a given or assumed datum. The first operation is required to enable the works to be designed while the second operation is required in the setting out of all kinds of engineering works. Levelling deals with measurements in a vertical plane.
A level line is a line lying in a level surface. It is, therefore, normal to the plumb line at all points.
A level surface is defined as a curved surface which at each point is perpendicular to the direction of gravity at the point. The surface of a still water is a truly level surface. Any surface parallel to the mean spheroidal surface of the earth is, therefore, a level surface.
It is a straight line tangential to the level line at a point. It is also perpendicular to the plumb line.
It is a line normal to the level line at a point. It is commonly considered to be the line defined by a plumb line.
Datum is any surface to which elevation are referred. The mean sea level affords a convenient datum world over, and elevations are commonly given as so much above or below sea level. It is often more convenient, however, to assume some other datum, specially, if only the relative elevation of points are required.
The elevation of a point on or near the surface of the earth is its vertical distance above or below an arbitrarily assumed level surface or datum. The difference in elevation between two points is the vertical distance between the two level surface in which the two points lie.
Vertical angle is an angle between two intersecting lines in a vertical plane. Generally, one of these lines is horizontal.
It is the average height of the sea for all stages of the tides. At any particular place it is derived by averaging the hourly tide heights over a long period of 19 years.
It is a relatively permanent point of reference whose elevation with respect to some assumed datum is known. It is used either as a starting point for levelling or as a point upon which to close as a check.
Three principle methods are used for determining differences in elevation, namely, barometric levelling, trigonometric levelling and spirit levelling.
Barometric levelling makes use of the phenomenon that difference in elevation between two points is proportional to the difference in atmospheric pressures at these points. A barometer, therefore, may be used and the readings observed at different points would yield a measure of the relative elevation of those points.
At a given point, the atmospheric pressure doesn’t remain constant in the course of the day, even in the course of an hour. The method is, therefore, relatively inaccurate and is little used in surveying work except on reconnaissance or exploratory survey.
At a given point, the atmospheric pressure doesn’t remain constant in the course of the day, even in the course of an hour. The method is, therefore, relatively inaccurate and is little used in surveying work except on reconnaissance or exploratory survey.
Trigonometric or Indirect levelling is the process of levelling in which the elevations of points are computed from the vertical angles and horizontal distances measured in the field, just as the length of any side in any triangle can be computed from proper trigonometric relations. In a modified form called stadia levelling, commonly used in mapping, both the difference in elevation and the horizontal distance between the points are directly computed from the measured vertical angles and staff readings.
It is that branch of levelling in which the vertical distances with respect to a horizontal line (perpendicular to the direction of gravity) may be used to determine the relative difference in elevation between two adjacent points. A horizontal plane of sight tangent to level surface at any point is readily established by means of a spirit level or a level vial. In spirit levelling, a spirit level and a sighting device (telescope) are combined and vertical distances are measured by observing on graduated rods placed on the points. The method is also known as direct levelling. It is the most precise method of determining elevations and the one most commonly used by engineers.
Types of Levelling Instruments
According to the general arrangement of various parts, the levels may be classified as:
1. Dumpy level,
2. Wye level,
3. Reversible level such as Cooke’s reversible level and Cushing’s level, and
4. Tilting level.
According to the general arrangement of various parts, the levels may be classified as:
1. Dumpy level,
2. Wye level,
3. Reversible level such as Cooke’s reversible level and Cushing’s level, and
4. Tilting level.
In surveying, triangulation is the process of determining the location of a point by measuring only angles to it from known points at either end of a fixed baseline, rather than measuring distances to the point directly as in trilateration. The point can then be fixed as the third point of a triangle with one known side and two known angles.
Triangulation can also refer to the accurate surveying of systems of very large triangles, called triangulation networks.
Have you ever wondered how your GPS receiver works? They use a technique called trilateration. Despite how GPS receivers are often confused with triangulation (which measures angles), they really don’t use angles at all. Trilateration involves measuring distances.
Measures distance not angles.
Using a simple two-dimensional example, let’s imagine we have three GPS satellites each with a known position in space
Using a simple two-dimensional example, let’s imagine we have three GPS satellites each with a known position in space
