Permanent Benchmarks

 

Permanent benchmarks

Definition of Permanent benchmarks

Permanent benchmarks are reference points that are established and maintained by government or private organizations for the purpose of surveying and mapping. They are typically physical markers, such as brass disks embedded in concrete, that are placed at a known location and elevation. Surveyors use these benchmarks to establish elevation and location data for construction, land use planning, and other purposes. They are called permanent because they are expected to remain in place for a long period of time, and are typically not moved or disturbed once they have been established.

Purpose of Permanent benchmarks

The purpose of permanent benchmarks is to provide a stable and reliable reference point for surveying and mapping activities. Surveyors use these benchmarks to establish precise elevation and location data for a wide range of applications, such as construction, land use planning, and infrastructure development. They can be used to set the elevation of a building's foundation, to ensure that a road or railway is built on the correct grade, or to establish flood plain boundaries. Permanent benchmarks are also used to establish the datum or reference point for a coordinate system, and to ensure that different survey and mapping projects are consistent and compatible with one another. Additionally, they are used as a reference point to check the accuracy of other measurements and surveying instruments over time.

Types of Permanent benchmarks

Horizontal benchmarks

Vertical benchmarks

A horizontal benchmark is a reference point that is established and maintained by government or private organizations for the purpose of surveying and mapping, and is typically a physical marker, such as a brass disk embedded in concrete. They are used to establish precise location data, typically in terms of longitude and latitude. Horizontal benchmarks are used in land surveying, cartography, and navigation.

A vertical benchmark, also called elevation benchmark, is a reference point established by government or private organizations for the purpose of surveying and mapping, and is typically a physical marker, such as a brass disk embedded in concrete, placed at a known elevation. They are used to establish precise elevation data, typically in terms of height above sea level. Vertical benchmarks are used in construction, land use planning, and other purposes where elevation data is required. These benchmarks are used to ensure that a building's foundation is set at the correct elevation, or to establish the gradients of roads and railways.

Maintenance of Permanent benchmarks

Maintenance of permanent benchmarks is an important step to ensure that the reference points remain accurate and reliable over time.

• Re-surveying when necessary

It is important to periodically re-survey the benchmarks to ensure that they have not moved or changed in elevation due to natural causes such as erosion, landslides, or subsidence. This can be done by visiting the benchmark location and re-measuring its coordinates and elevation using the same survey equipment and techniques that were used to establish it.

• Replacement of damaged or vandalized benchmarks

Benchmarks can be damaged or vandalized over time, which can make them difficult or impossible to use for surveying and mapping purposes. When this happens, the benchmark should be replaced with a new marker or monument. This typically involves installing a new marker in the same location as the original benchmark, and re-surveying the coordinates and elevation to ensure that the new benchmark is accurate and reliable. The replacement should be registered with the government agency and updated in their database.

It is important to have a regular maintenance schedule for benchmark, to make sure the integrity of benchmark is maintained over time. This can include regular inspections, re-surveying, and replacement of damaged or vandalized markers. The surveying agency should also maintain a record of the benchmark data and have a process in place to recover the benchmark in case it is disturbed or destroyed.

Advantages of Permanent benchmarks

• Stable reference point for surveying and mapping: 

Permanent benchmarks provide a stable and reliable reference point for surveying and mapping activities. They are designed to remain in place for a long period of time, and are typically not moved or disturbed once they have been established. This ensures that the reference point remains accurate and consistent, and can be used for a wide range of applications.

 

• Accurate measurements for large-scale projects:

Permanent benchmarks allow for accurate measurements to be taken for large-scale projects such as construction, land use planning, and infrastructure development. They provide a common reference point that can be used to ensure that different survey and mapping projects are consistent and compatible with one another.

• Establishes elevation for floodplain mapping and other applications: 

Permanent benchmarks are used to establish precise elevation data, typically in terms of height above sea level. This is important in applications such as floodplain mapping, where accurate elevation data is critical for determining the risk of flooding. They can also be used to ensure that a building's foundation is set at the correct elevation, or to establish the gradients of roads and railways.

• Regularly maintained for accuracy and availability: 

Permanent benchmarks are regularly maintained to ensure their accuracy and availability. This can include re-surveying, replacing damaged or vandalized markers, and updating registration with the government agency. This ensures that the benchmarks remain accurate and reliable over time, and can be easily located and used by other surveyors and mapping professionals in the future.

These advantages make Permanent benchmarks an essential tool for surveying and mapping, providing a foundation of accurate, stable data that can be used for a wide range of projects, from small-scale construction to large-scale infrastructure development.

• Provide a stable reference point for surveying and mapping activities.
• Allow for accurate measurements, particularly for large-scale projects such as construction of roads and bridges.
• Establish the elevation of a specific location, which is used in floodplain mapping and other applications.
• Can be divided into two main categories: horizontal benchmarks and vertical benchmarks.
• Established using a rigorous process that involves multiple steps.
• Registered with the relevant government agency and included in a database that is available to the public.
• Regularly maintained to ensure accuracy and availability.
• Provide a reliable source of information for planning, construction and other projects.
• Cost-effective in the long run as it eliminates the need for frequent re-surveys.

Conclusion

• Importance of Permanent benchmarks in surveying, mapping and other geospatial applications.

In conclusion, Permanent benchmarks are essential tools for surveying, mapping, and other geospatial applications. They provide a stable and reliable reference point for determining precise location and elevation data, which is critical for a wide range of activities, including construction, land use planning, and infrastructure development. Permanent benchmarks are regularly maintained to ensure their accuracy and availability. They are also registered with government agencies and can be easily located and used by other surveyors and mapping professionals in the future. Their importance is in their ability to provide accurate and consistent data over time, which is critical for the success of geospatial projects. They are the foundation of accurate location and elevation data that is used in many areas of our lives, from building construction to weather forecasting, and many more.

• Government agencies' role in establishing and maintaining Permanent benchmarks.

Government agencies play an important role in establishing and maintaining Permanent benchmarks. They are typically responsible for surveying and mapping large areas of land, and for providing accurate and reliable location and elevation data for a wide range of applications.

In establishing Permanent benchmarks, government agencies typically conduct the initial survey to establish the coordinates and elevation of the reference point, and then install a marker or monument at the location. They also register the benchmark with the appropriate government agency, such as the National Geodetic Survey or a state survey agency, for inclusion in their database of benchmarks. This registration is important to ensure that the benchmark can be located and used by other surveyors and mapping professionals in the future.

In terms of maintenance, government agencies are responsible for monitoring the condition of existing benchmarks and re-surveying them when necessary to ensure that they have not moved or changed in elevation due to natural causes such as erosion, landslides, or subsidence. They also are responsible for replacing damaged or vandalized benchmarks to ensure that they remain accurate and reliable. Additionally, they maintain a record of the benchmark data and have a process in place to recover the benchmark in case it is disturbed or destroyed.

Overall, government agencies play a crucial role in ensuring that Permanent benchmarks remain accurate and reliable over time, and can be easily located and used by other surveyors and mapping professionals in the future.