Elevation benchmark

A benchmark is an officially surveyed and permanently marked point on the ground whose elevation above sea level (ASL) is precisely known and geodetically documented. It serves as a reference point for surveying, construction projects, and land-use planning. Elevation benchmarks are part of the official benchmark network maintained by state surveying authorities and are registered in Bavaria with the State Office for Digitalization, Broadband, and Surveying (LDBV).

Function and Technical Significance

Elevation benchmarks are used in construction projects to precisely determine terrain elevations and to accurately survey the location of structures. Without a known elevation reference point, it is not possible to create terrain models, plan terrain profiles, or carry out earthworks correctly. Accurate knowledge of terrain elevation is essential, particularly for sloped properties, underground parking garage planning, or flood protection measures. Surveyors use the nearest elevation control point as a starting and control point.

The Normal Zero Elevation (NHN) is the standard reference surface for elevation data in Germany and is based on mean sea level. It replaces the former Zero Elevation (HN) and has been the mandatory reference for all official elevation data in Germany since 1996. All elevation benchmarks are specified in NHN and allow for the comparison of terrain elevations across different locations.

Relevance for Property Purchase and Construction Planning

When purchasing a property-especially on sloping terrain or for complex development projects-it is important to verify whether suitable elevation benchmarks are available nearby. If they are absent or located far away, surveying services will incur higher costs. In Bavaria, the location and coordinates of elevation benchmarks can be accessed via the BayernAtlas geodata portal. For urban land-use planning and the cadastral boundary register, elevation benchmarks are an indispensable foundation for all planning.

Precise ground elevation plays a crucial role in earthworks, basement planning, and the calculation of clearance distances. Anyone planning a basement must know whether the water table or the underlying bedrock allows for basement construction-and for this, precise elevation data linked to a fixed elevation point is indispensable.

Elevation benchmarks and flood protection

In areas at risk of flooding-including along the Regnitz, Pegnitz, and Rednitz rivers in Franconia-elevation benchmarks serve as the basis for calculating flood boundaries and protective measures. Anyone purchasing a property in a potential flood zone can use elevation benchmarks and official terrain models to verify whether the property lies above or below defined flood marks. This information is equally relevant for purchasing decisions and insurance matters.

The flood hazard maps from the Bavarian State Office for the Environment are based on precise digital terrain models derived from a dense network of elevation benchmarks. Anyone wishing to determine the elevation of their property relative to known flood marks can have this done by a qualified surveyor, who will anchor the measurement to the nearest elevation benchmark.

Practical Tip for Property Owners in Nuremberg and Franconia

In the Nuremberg metropolitan region, elevation benchmarks can be found on many public buildings, bridge piers, and special surveying bolts embedded in sidewalks. The Office for Geoinformation and Land Use Planning of the City of Nuremberg is the right point of contact for questions regarding official benchmarks. For construction projects, property subdivisions, or boundary determinations, we work closely with licensed surveying firms that professionally integrate elevation benchmarks.

For property owners planning construction projects, we recommend determining the coordinates of the nearest elevation benchmark early on. This saves time and money, as the surveyor can work more efficiently when they know the baseline data.

Frequently Asked Questions

What is the difference between a benchmark and a position control point?

Benchmarks indicate only the elevation above mean sea level (MSL). Position or survey points define the two-dimensional position (x/y coordinates) within a coordinate system. Trigonometric points (TP) can combine both-position and elevation.

Can I remove a benchmark from my property?

No. Benchmarks are protected by public law; their removal or damage constitutes an administrative offense and may be punishable by law. If relocation is unavoidable for structural reasons, the surveying office must be contacted in advance. In such cases, the costs for establishing a new benchmark are generally borne by the party requesting the work.

Where can I look up elevation benchmarks in Bavaria?

In the BayernAtlas (www.bayernatlas.de), you can search for benchmarks from the official benchmark network by location and elevation. For exact coordinates and descriptions, please contact the LDBV Bavaria.

How precise are the elevation benchmarks?

Official elevation benchmarks have a measurement accuracy in the millimeter to centimeter range. They are checked at regular intervals and re-surveyed as needed, since geological settlement or construction projects can alter their position. The current elevation value and the date of the last inspection are documented in the official descriptions.

Types of Elevation Control Points

The official control point network distinguishes between several classes of elevation control points. Leveling points (NivP) form the primary network: They are determined by precise geometric leveling and offer the highest accuracy. Secondary survey points are derived from these and are used in daily surveying practice. In cities, elevation benchmarks are often embedded as bolts in building walls, bridge piers, or curbs-frequently marked with a small brass plate or a stamped cross. These inconspicuous points form the physical foundation of all terrain models.

Terrain Models and Digital Data

State surveying agencies derive digital terrain models (DTMs) from the official elevation benchmarks. Bavaria provides several DTM products: The DTM1 (1-meter grid) is suitable for detailed construction projects, while the DTM5 (5-meter grid) is used for land-use planning. These models are used, among other things, for slope runoff analyses, noise maps, and floodplain calculations. Anyone purchasing a property on a slope or in a hollow can view the official terrain model via BayernAtlas and thus assess early on how stormwater drains off the property-an important consideration for drainage planning and basement construction.

Costs and Procedures for Construction Projects

If a control point must be established or secured as part of a construction project, costs are incurred that are borne by the project sponsor. Fees from the surveying office and, if applicable, costs for geodetic re-surveying apply for the establishment of a new control point. Depending on the scope of work, these can amount to several thousand euros. For larger construction projects-such as apartment buildings, commercial structures, and infrastructure projects-the connection to the control point network is a mandatory component of the surveying documents that must be attached to the building application.

Back to the Real Estate Glossary.